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• 1. [Article] Model for Network Assignment Problem of Capacitated Freight with Disruptions

  A modeling framework is proposed for the freight network assignment problem with recourse, network travel time and cost disruptions, and link flow capacity constraints. "Recourse" is defined as the ability ...

  Citation × Citation Citation Abstract Copy Title: Model for Network Assignment Problem of Capacitated Freight with Disruptions Author: Figliozzi, Miguel, Unnikrishnan, Avinash, Shahabi, Mehrdad Year: 2012 A modeling framework is proposed for the freight network assignment problem with recourse, network travel time and cost disruptions, and link flow capacity constraints. "Recourse" is defined as the ability of a user to reconsider and adapt his or her routing decisions in response to newly acquired information about network disruption. When real-time tracking and monitoring of network shipments allow companies a routing recourse, network capacity must be simultaneously considered. If a disruption significantly alters network flows, the capacity of alternative or secondary routes may be quickly reached. A new freight mathematical model with a capacitated network and adaptive routing was developed and solved. Results showed that simultaneous consideration of recourse and capacity constraints was superior to benchmark results obtained with nonadaptive deterministic behavior. Title: Model for Network Assignment Problem of Capacitated Freight with Disruptions Author: Figliozzi, Miguel, Unnikrishnan, Avinash, Shahabi, Mehrdad Year: 2012 A modeling framework is proposed for the freight network assignment problem with recourse, network travel time and cost disruptions, and link flow capacity constraints. "Recourse" is defined as the ability of a user to reconsider and adapt his or her routing decisions in response to newly acquired information about network disruption. When real-time tracking and monitoring of network shipments allow companies a routing recourse, network capacity must be simultaneously considered. If a disruption significantly alters network flows, the capacity of alternative or secondary routes may be quickly reached. A new freight mathematical model with a capacitated network and adaptive routing was developed and solved. Results showed that simultaneous consideration of recourse and capacity constraints was superior to benchmark results obtained with nonadaptive deterministic behavior. Close

• 2. [Article] Congestion and Emissions Mitigation: A Comparison of Capacity, Demand, and Efficiency Based Strategies

  Capacity, demand, and vehicle based emissions reduction strategies are compared for several pollutants employing aggregate US congestion and vehicle fleet condition data. We find that congestion mitigation ...

  Citation × Citation Citation Abstract Copy Title: Congestion and Emissions Mitigation: A Comparison of Capacity, Demand, and Efficiency Based Strategies Author: Bigazzi, Alexander Y., Figliozzi, Miguel Year: 2012 Capacity, demand, and vehicle based emissions reduction strategies are compared for several pollutants employing aggregate US congestion and vehicle fleet condition data. We find that congestion mitigation does not inevitably lead to reduced emissions; the net effect of mitigation depends on the balance of induced travel demand and increased vehicle efficiency that in turn depend on the pollutant, congestion level, and fleet composition. In the long run, capacity-based congestion improvements within certain speed intervals can reasonably be expected to increase emissions of CO2e, CO, and NOx through increased vehicle travel volume. Better opportunities for emissions reductions exist for HC and PM2.5 emissions, and on more heavily congested arterials. Advanced-efficiency vehicles with emissions rates that are less sensitive to congestion than conventional vehicles generate less emissions co-benefits from congestion mitigation. Title: Congestion and Emissions Mitigation: A Comparison of Capacity, Demand, and Efficiency Based Strategies Author: Bigazzi, Alexander Y., Figliozzi, Miguel Year: 2012 Capacity, demand, and vehicle based emissions reduction strategies are compared for several pollutants employing aggregate US congestion and vehicle fleet condition data. We find that congestion mitigation does not inevitably lead to reduced emissions; the net effect of mitigation depends on the balance of induced travel demand and increased vehicle efficiency that in turn depend on the pollutant, congestion level, and fleet composition. In the long run, capacity-based congestion improvements within certain speed intervals can reasonably be expected to increase emissions of CO2e, CO, and NOx through increased vehicle travel volume. Better opportunities for emissions reductions exist for HC and PM2.5 emissions, and on more heavily congested arterials. Advanced-efficiency vehicles with emissions rates that are less sensitive to congestion than conventional vehicles generate less emissions co-benefits from congestion mitigation. Close

• 3. [Article] Environmental Durability of Reinforced Concrete Deck Girders Strengthened for Shear with Surface Bonded Carbon Fiber-Reinforced Polymer

  This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for ...

  Citation × Citation Citation Abstract Copy Title: Environmental Durability of Reinforced Concrete Deck Girders Strengthened for Shear with Surface Bonded Carbon Fiber-Reinforced Polymer Author: Higgins, Christopher, Dawson, Matthew R., Mitchell, Mikal M., Sopal, Gautam, Senturk, A. Ekin Year: 2009 This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort included determining the role of freeze-thaw, moisture, and fatigue on structural performance and developing analytical design procedures that account for durability. The results showed that moisture infiltration behind the CFRP, combined with freeze-thaw, was critical in reducing shear panel stiffness and shear capacity. Long-term moisture exposure alone produced only a minor decrease in shear capacity. Freeze-thaw, combined with fatigue, had little effect on shear capacity if water infiltration was minimized. Fatigue caused some debonding, but the debonding was not significant enough to affect capacity. Use of ACI-318 with ACI 440 provided conservative predicted shear strengths after environmental exposure. However, the ACI approach did not provide uniform levels of safety because the observed conservatism was built into the prediction for the unstrengthened base specimens but not for the CFRP contribution. Consequently, a recommendation of the research is to apply the environmental exposure factor at the final design step to limit the effective CFRP stress/strain. For locations with very large numbers of wet freeze-thaw cycles and extended exposure to continuous moisture, the environmental reduction factors should be reduced even further. To better predict the CFRP bond strength demands that can occur due to shear-moment interaction, a further check of the design should be made beyond those required by ACI-440. Title: Environmental Durability of Reinforced Concrete Deck Girders Strengthened for Shear with Surface Bonded Carbon Fiber-Reinforced Polymer Author: Higgins, Christopher, Dawson, Matthew R., Mitchell, Mikal M., Sopal, Gautam, Senturk, A. Ekin Year: 2009 This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort included determining the role of freeze-thaw, moisture, and fatigue on structural performance and developing analytical design procedures that account for durability. The results showed that moisture infiltration behind the CFRP, combined with freeze-thaw, was critical in reducing shear panel stiffness and shear capacity. Long-term moisture exposure alone produced only a minor decrease in shear capacity. Freeze-thaw, combined with fatigue, had little effect on shear capacity if water infiltration was minimized. Fatigue caused some debonding, but the debonding was not significant enough to affect capacity. Use of ACI-318 with ACI 440 provided conservative predicted shear strengths after environmental exposure. However, the ACI approach did not provide uniform levels of safety because the observed conservatism was built into the prediction for the unstrengthened base specimens but not for the CFRP contribution. Consequently, a recommendation of the research is to apply the environmental exposure factor at the final design step to limit the effective CFRP stress/strain. For locations with very large numbers of wet freeze-thaw cycles and extended exposure to continuous moisture, the environmental reduction factors should be reduced even further. To better predict the CFRP bond strength demands that can occur due to shear-moment interaction, a further check of the design should be made beyond those required by ACI-440. Close

• 4. [Article] Experimental Investigation of CFRP Wrapped Square Non-ductile Reinforced Concrete Columns

  The use of fiber-reinforced polymers (FRP) for retrofitting or strengthening deficient concrete columns noticeably increased in the past few decades. Plenty of research has been conducted on the behavior ...

  Citation × Citation Citation Abstract Copy Title: Experimental Investigation of CFRP Wrapped Square Non-ductile Reinforced Concrete Columns Author: Al-Khafaji, Hayder Lateef Year: 2016 The use of fiber-reinforced polymers (FRP) for retrofitting or strengthening deficient concrete columns noticeably increased in the past few decades. Plenty of research has been conducted on the behavior of FRP-strengthened circular concrete columns, but far less research has dealt with non-circular columns. In the current study, the focus was to investigate the behavior of square columns with low to medium grade concrete and low steel reinforcement that were strengthened using carbon fiber reinforced polymer (CFRP) wrap. In the experimental portion of this investigation, twelve short square reinforced concrete columns (5" x 5" in cross section and 12" high) were cast and tested under concentric axial loading. The specimens were divided evenly into two series, named C2 and C4. In the first series, C2, six column specimens were cast with 2000-psi concrete, representing low-grade concrete. One column was a "control specimen" designed based on older non-seismic codes. A second column, another "control specimen", was designed based on the current seismic design code, ACI 318-14. The four remaining columns were wrapped with CFRP sheets, but with a different number of CFRP wraps. The same scheme was followed for the specimens of the second series (C4), but they were cast with 4000-psi concrete, representing medium grade concrete. Thus, the main parameters considered in the current study were the concrete compressive strength and the thickness of the CFRP jacket (number of wraps). Those two parameters were utilized to investigate the effectiveness of the CFRP confinement in enhancing the axial load carrying capacity and ductility of the strengthened columns. Test results confirmed that the confinement produced by the CFRP jacket enhanced the axial load-carrying capacity, axial strain capacity, and energy absorption if compared to unwrapped columns. In addition, the results showed that there should be an effective thickness for the CFRP jacket in order to achieve a significant enhancement in the performance of the strengthened columns. Moreover, the test results demonstrated that the effectiveness of the CFRP confinement was more pronounced in the case of the low-grade concrete columns (Series C2). Title: Experimental Investigation of CFRP Wrapped Square Non-ductile Reinforced Concrete Columns Author: Al-Khafaji, Hayder Lateef Year: 2016 The use of fiber-reinforced polymers (FRP) for retrofitting or strengthening deficient concrete columns noticeably increased in the past few decades. Plenty of research has been conducted on the behavior of FRP-strengthened circular concrete columns, but far less research has dealt with non-circular columns. In the current study, the focus was to investigate the behavior of square columns with low to medium grade concrete and low steel reinforcement that were strengthened using carbon fiber reinforced polymer (CFRP) wrap. In the experimental portion of this investigation, twelve short square reinforced concrete columns (5" x 5" in cross section and 12" high) were cast and tested under concentric axial loading. The specimens were divided evenly into two series, named C2 and C4. In the first series, C2, six column specimens were cast with 2000-psi concrete, representing low-grade concrete. One column was a "control specimen" designed based on older non-seismic codes. A second column, another "control specimen", was designed based on the current seismic design code, ACI 318-14. The four remaining columns were wrapped with CFRP sheets, but with a different number of CFRP wraps. The same scheme was followed for the specimens of the second series (C4), but they were cast with 4000-psi concrete, representing medium grade concrete. Thus, the main parameters considered in the current study were the concrete compressive strength and the thickness of the CFRP jacket (number of wraps). Those two parameters were utilized to investigate the effectiveness of the CFRP confinement in enhancing the axial load carrying capacity and ductility of the strengthened columns. Test results confirmed that the confinement produced by the CFRP jacket enhanced the axial load-carrying capacity, axial strain capacity, and energy absorption if compared to unwrapped columns. In addition, the results showed that there should be an effective thickness for the CFRP jacket in order to achieve a significant enhancement in the performance of the strengthened columns. Moreover, the test results demonstrated that the effectiveness of the CFRP confinement was more pronounced in the case of the low-grade concrete columns (Series C2). Close

• 5. [Article] Torsional Strengthening of Reinforced Concrete Beams Using CFRP Composites

  Few decades ago, there were no guidelines for torsion design of reinforced concrete (RC) beams. Hence, many existing beams in older buildings have a lack of adequate torsional strength since they were ...

  Citation × Citation Citation Abstract Copy Title: Torsional Strengthening of Reinforced Concrete Beams Using CFRP Composites Author: Rafeeq, Ranj Year: 2016 Few decades ago, there were no guidelines for torsion design of reinforced concrete (RC) beams. Hence, many existing beams in older buildings have a lack of adequate torsional strength since they were not properly designed for torsion. One way to regain/rehabilitate adequate torsional strength is through application of externally bonded carbon fiber reinforced polymers (CFRP). To date, American Concrete Institute (ACI) code, as well as other building codes, do not have recommendations or provisions for strengthening RC beams for torsion using fiber-reinforced polymer (FRP) composites due to the inexistence of conclusive experimental and analytical data. Of the very limited works on this behavior, the majority of the focus has been devoted to experimental works. Realistic spandrel beams in a building that lack torsional strength were modelled in this research, and strengthened to examine various behaviors such as load capacity, deflection, torque, twist, crack propagation, ductility, and failure modes. For this purpose, six RC beams were tested: four reference beams and two strengthened beams were used to observe additional capacity through the use of carbon fiber-reinforced polymer (CFRP) sheets. To strengthen the beams, one layer of sheets was completely wrapped around them. Results show an additional torsional capacity of 63% and 178% relative to their respective reference beams. Through strengthening, modes of failure of the beams changed from brittle torsion-dominated failure to shear-flexure failure in both beams. The study also included crack pattern and ductility of test beams. Cracks became smaller in width and more evenly distributed across the torsion-loaded area, and torsional ductility was enhanced by 266% and 165% respectively. Flexural ductility was also greatly enhanced by more than five folds. Finally, using ACI 318-14, ACI 440.2R-02, and available formulae in the literature, the beams were analyzed and the respective values were compared. Title: Torsional Strengthening of Reinforced Concrete Beams Using CFRP Composites Author: Rafeeq, Ranj Year: 2016 Few decades ago, there were no guidelines for torsion design of reinforced concrete (RC) beams. Hence, many existing beams in older buildings have a lack of adequate torsional strength since they were not properly designed for torsion. One way to regain/rehabilitate adequate torsional strength is through application of externally bonded carbon fiber reinforced polymers (CFRP). To date, American Concrete Institute (ACI) code, as well as other building codes, do not have recommendations or provisions for strengthening RC beams for torsion using fiber-reinforced polymer (FRP) composites due to the inexistence of conclusive experimental and analytical data. Of the very limited works on this behavior, the majority of the focus has been devoted to experimental works. Realistic spandrel beams in a building that lack torsional strength were modelled in this research, and strengthened to examine various behaviors such as load capacity, deflection, torque, twist, crack propagation, ductility, and failure modes. For this purpose, six RC beams were tested: four reference beams and two strengthened beams were used to observe additional capacity through the use of carbon fiber-reinforced polymer (CFRP) sheets. To strengthen the beams, one layer of sheets was completely wrapped around them. Results show an additional torsional capacity of 63% and 178% relative to their respective reference beams. Through strengthening, modes of failure of the beams changed from brittle torsion-dominated failure to shear-flexure failure in both beams. The study also included crack pattern and ductility of test beams. Cracks became smaller in width and more evenly distributed across the torsion-loaded area, and torsional ductility was enhanced by 266% and 165% respectively. Flexural ductility was also greatly enhanced by more than five folds. Finally, using ACI 318-14, ACI 440.2R-02, and available formulae in the literature, the beams were analyzed and the respective values were compared. Close

• 6. [Article] Behavior of Concrete Beams with Corroded Reinforcement Retrofitted with Carbon Fiber Reinforced Polymer

  Severe premature deterioration has been reported in a large number of reinforced concrete (RC) structures in corrosive environments. This research project focused on the behavior of beams that contained ...

  Citation × Citation Citation Abstract Copy Title: Behavior of Concrete Beams with Corroded Reinforcement Retrofitted with Carbon Fiber Reinforced Polymer Author: Lingga, Needa M. Year: 2016 Severe premature deterioration has been reported in a large number of reinforced concrete (RC) structures in corrosive environments. This research project focused on the behavior of beams that contained corroded steel and were retrofitted with CFRP. The steel in RC beams were assumed to be fully corroded, representing the most severe loss in steel cross-section. Unidirectional CFRP sheets were used to strengthen the deteriorated beams. The experimental program included testing five simply supported rectangular cross section concrete beams. All beams were approximately 1/3rd scale models, 4in. x 6in. cross sections, and 6ft. long. In three beams, the oiled steel rebars for flexure and shear were safely pulled out of the formwork after the concrete had cured a few hours, leaving voids. This technique was used to represent the total loss in steel cross-section in an extremely corrosive environment. The first specimen was a control beam with voids representing deteriorated steel. The second specimen was a plain concrete beam without voids. The third beam was another control specimen with flexural and shear reinforcement intact, representing the “original” beam before steel corrosion. The two remaining deteriorated beams were strengthened by externally bonding one and two layers of CFRP in the longitudinal and transverse directions. Beams were tested under third-point loading. Load carrying capacity, deflection, and ductility of the beams were measured. Test results showed that one layer of CFRP increased the load capacity to slightly higher than the “original” control beam, and two layers of CFRP increased it by a factor of two. The retrofitted specimens had a higher stiffness under service load conditions. The predict contribution of CFRP to flexure and shear capacities based on ACI 440.2R guidelines were in good agreement with test results. Title: Behavior of Concrete Beams with Corroded Reinforcement Retrofitted with Carbon Fiber Reinforced Polymer Author: Lingga, Needa M. Year: 2016 Severe premature deterioration has been reported in a large number of reinforced concrete (RC) structures in corrosive environments. This research project focused on the behavior of beams that contained corroded steel and were retrofitted with CFRP. The steel in RC beams were assumed to be fully corroded, representing the most severe loss in steel cross-section. Unidirectional CFRP sheets were used to strengthen the deteriorated beams. The experimental program included testing five simply supported rectangular cross section concrete beams. All beams were approximately 1/3rd scale models, 4in. x 6in. cross sections, and 6ft. long. In three beams, the oiled steel rebars for flexure and shear were safely pulled out of the formwork after the concrete had cured a few hours, leaving voids. This technique was used to represent the total loss in steel cross-section in an extremely corrosive environment. The first specimen was a control beam with voids representing deteriorated steel. The second specimen was a plain concrete beam without voids. The third beam was another control specimen with flexural and shear reinforcement intact, representing the “original” beam before steel corrosion. The two remaining deteriorated beams were strengthened by externally bonding one and two layers of CFRP in the longitudinal and transverse directions. Beams were tested under third-point loading. Load carrying capacity, deflection, and ductility of the beams were measured. Test results showed that one layer of CFRP increased the load capacity to slightly higher than the “original” control beam, and two layers of CFRP increased it by a factor of two. The retrofitted specimens had a higher stiffness under service load conditions. The predict contribution of CFRP to flexure and shear capacities based on ACI 440.2R guidelines were in good agreement with test results. Close

• 7. [Article] Key Aspects for LRFD Implementation of Driven Pile Capacity by Dynamic Methods

  Inputs and interpretation procedures for pile wave equation analysis, which correlates measured field dynamic driving response to axial pile static capacity, are highly dependent on site-specific soil ...

  Citation × Citation Citation Abstract Copy Title: Key Aspects for LRFD Implementation of Driven Pile Capacity by Dynamic Methods Author: Ehrlich, Natalie R Year: 2015 Inputs and interpretation procedures for pile wave equation analysis, which correlates measured field dynamic driving response to axial pile static capacity, are highly dependent on site-specific soil conditions and field practices. The 6th Edition of the AASHTO LRFD Bridge Design Specifications provide generalized guidelines for pile design, but do not account for variability in region-specific soils and field practices. A comprehensive literature review of region-specific resistance factor recalibration efforts across the U.S. has given insight into the range of implementation issues encountered, especially the key decisions around choosing a restrike (BOR), along with measures of efficiency and treatment of time-dependent capacity gain through pile set-up for BOR. A reevaluation and statistical exploration of cases within the extensive Portland State University (PSU) Pile Load Test Database offers special insight into the implementation issues for the PSU recalibration effort specific to Oregon Department of Transportation (ODOT) and Pacific Northwest Practice. The information gathered from this research provides a general commentary on increased foundation reliability and guidance for approaches to implementation of LRFD bridge pile foundation design into practice. Title: Key Aspects for LRFD Implementation of Driven Pile Capacity by Dynamic Methods Author: Ehrlich, Natalie R Year: 2015 Inputs and interpretation procedures for pile wave equation analysis, which correlates measured field dynamic driving response to axial pile static capacity, are highly dependent on site-specific soil conditions and field practices. The 6th Edition of the AASHTO LRFD Bridge Design Specifications provide generalized guidelines for pile design, but do not account for variability in region-specific soils and field practices. A comprehensive literature review of region-specific resistance factor recalibration efforts across the U.S. has given insight into the range of implementation issues encountered, especially the key decisions around choosing a restrike (BOR), along with measures of efficiency and treatment of time-dependent capacity gain through pile set-up for BOR. A reevaluation and statistical exploration of cases within the extensive Portland State University (PSU) Pile Load Test Database offers special insight into the implementation issues for the PSU recalibration effort specific to Oregon Department of Transportation (ODOT) and Pacific Northwest Practice. The information gathered from this research provides a general commentary on increased foundation reliability and guidance for approaches to implementation of LRFD bridge pile foundation design into practice. Close

• 8. [Article] Value of Travel Time Reliability Part II: A Study of Tradeoffs Between Travel Reliability, Congestion Mitigation Strategies and Emissions

  Capacity, demand, and vehicle based emissions reduction strategies are compared for several pollutants employing aggregate US congestion and vehicle fleet condition data. We find that congestion mitigation ...

  Citation × Citation Citation Abstract Copy Title: Value of Travel Time Reliability Part II: A Study of Tradeoffs Between Travel Reliability, Congestion Mitigation Strategies and Emissions Author: Figliozzi, Miguel A., Bigazzi, Alexander Y. Year: 2012 Capacity, demand, and vehicle based emissions reduction strategies are compared for several pollutants employing aggregate US congestion and vehicle fleet condition data. We find that congestion mitigation does not inevitably lead to reduced emissions; the net effect of mitigation depends on the balance of induced travel demand and increased vehicle efficiency that in turn depend on the pollutant, congestion level, and fleet composition. In the long run, capacity-based congestion improvements within certain speed intervals can reasonably be expected to increase emissions of CO2e, CO, and NOx through increased vehicle travel volume. Better opportunities for emissions reductions exist for HC and PM2.5 emissions, and on more heavily congested arterials. Advanced-efficiency vehicles with emissions rates that are less sensitive to congestion than conventional vehicles generate less emissions co-benefits from congestion mitigation. Title: Value of Travel Time Reliability Part II: A Study of Tradeoffs Between Travel Reliability, Congestion Mitigation Strategies and Emissions Author: Figliozzi, Miguel A., Bigazzi, Alexander Y. Year: 2012 Capacity, demand, and vehicle based emissions reduction strategies are compared for several pollutants employing aggregate US congestion and vehicle fleet condition data. We find that congestion mitigation does not inevitably lead to reduced emissions; the net effect of mitigation depends on the balance of induced travel demand and increased vehicle efficiency that in turn depend on the pollutant, congestion level, and fleet composition. In the long run, capacity-based congestion improvements within certain speed intervals can reasonably be expected to increase emissions of CO2e, CO, and NOx through increased vehicle travel volume. Better opportunities for emissions reductions exist for HC and PM2.5 emissions, and on more heavily congested arterials. Advanced-efficiency vehicles with emissions rates that are less sensitive to congestion than conventional vehicles generate less emissions co-benefits from congestion mitigation. Close

• 9. [Article] Modeling the Response of Dissolved Oxygen to Phosphorus Loading in Lake Spokane

  Mathematical models of hydrodynamics and water quality are often used to determine the assimilative capacity of a waterbody when waterbodies violate state water quality standards. A model of the Spokane ...

  Citation × Citation Citation Abstract Copy Title: Modeling the Response of Dissolved Oxygen to Phosphorus Loading in Lake Spokane Author: Wells, Scott A., Berger, Chris J. Year: 2016 Mathematical models of hydrodynamics and water quality are often used to determine the assimilative capacity of a waterbody when waterbodies violate state water quality standards. A model of the Spokane River and Lake Spokane in eastern Washington was developed to evaluate the assimilative capacity of the waterbody by setting a total maximum daily load (TMDL). A CE-QUAL-W2 model of this system was developed to establish the TMDL limits for the critical low-flow year of 2001. A recent paper evaluated this model and raised several issues about the validity of this model application as a regulatory tool related to its ability to predict total phosphorus, dissolved oxygen, and chlorophyll a relationships. This paper analyzes the validity of their critiques. For example, the critique used an incorrect formula to calculate total phosphorus inflows into Lake Spokane and used a volume-weighted minimum hypolimnetic dissolved oxygen (DOmin) that was not representative of hypolimnetic conditions. They also assumed incorrectly that the hydrologic, meteorological, operational, and sediment conditions of the 2001 TMDL model would be representative of conditions in other years. Although the water quality model of Lake Spokane can be improved, the critique does not invalidate the model as a tool to evaluate how the lake responds to nutrient environmental controls. Title: Modeling the Response of Dissolved Oxygen to Phosphorus Loading in Lake Spokane Author: Wells, Scott A., Berger, Chris J. Year: 2016 Mathematical models of hydrodynamics and water quality are often used to determine the assimilative capacity of a waterbody when waterbodies violate state water quality standards. A model of the Spokane River and Lake Spokane in eastern Washington was developed to evaluate the assimilative capacity of the waterbody by setting a total maximum daily load (TMDL). A CE-QUAL-W2 model of this system was developed to establish the TMDL limits for the critical low-flow year of 2001. A recent paper evaluated this model and raised several issues about the validity of this model application as a regulatory tool related to its ability to predict total phosphorus, dissolved oxygen, and chlorophyll a relationships. This paper analyzes the validity of their critiques. For example, the critique used an incorrect formula to calculate total phosphorus inflows into Lake Spokane and used a volume-weighted minimum hypolimnetic dissolved oxygen (DOmin) that was not representative of hypolimnetic conditions. They also assumed incorrectly that the hydrologic, meteorological, operational, and sediment conditions of the 2001 TMDL model would be representative of conditions in other years. Although the water quality model of Lake Spokane can be improved, the critique does not invalidate the model as a tool to evaluate how the lake responds to nutrient environmental controls. Close

• 10. [Article] Application of LRFD Geotechnical Principles for Pile Supported Bridges in Oregon: Phase 1

  Bridge foundations must be designed based on acceptable risks of failure. To secure rapid implementation of Load Resistance Factor Design (LRFD) principles for foundation design, the American Association ...

  Citation × Citation Citation Abstract Copy Title: Application of LRFD Geotechnical Principles for Pile Supported Bridges in Oregon: Phase 1 Author: Smith, Trevor D., Dusicka, Peter Year: 2009 Bridge foundations must be designed based on acceptable risks of failure. To secure rapid implementation of Load Resistance Factor Design (LRFD) principles for foundation design, the American Association of State Highway and Transportation Officials (AASHTO) and the Federal Highway Administration (FHWA) are requiring their use through AASHTO code. The Bridge Section of the Oregon Department of Transportation (ODOT) has responsibility for satisfactory design of all the bridge structures across the state’s highway system. The widespread geotechnical adoption of the LRFD code throughout state DOTs has been difficult in the case of deep foundations due to regional differences and in some cases a lack of any close match to DOT foundation practices. This lack of matching stems from the source research conducted on which the code is based, documented as NCHRP 507. For ODOT, the evaluation of nominal axial static capacity for each driven pile in the field is conducted by dynamic methods and AASHTO offers resistance factors for these techniques. ODOT typically uses the wave equation software (WEAP) applied at the end of initial driving, EOID, and occasionally at the beginning of pile restrike (BOR) to capture increases in capacity from set-up. This study reports that, based on past and new surveys, ODOT practice is reasonably typical for DOT practice in sands, silts, and clays. The AASHTO resistance factor, φ, for WEAP is at EOID and is too low for the efficient design of piles to match the likely probabilities of pile failure. The survey of Northwest state DOTs revealed that 80% of the DOTs believe that a φ of 0.4 is conservative and 37.5 % do not use the AASHTO-sanctioned φ of 0.4. Matching LRFD to allowable stress design (ASD) by direct calibration for a single pile, without any reported capacity bias, sets φ as 0.55 to match the ASD factor of safety of 2.5. An ODOT case history of a recently completed pilesupported bridge designed and constructed to FHWA and AASHTO ASD standards in use at that time, shows the number of piles at the bent studied would be doubled under new AASHTO requirements. This suggests the standard will add considerable pile foundation costs to all new bridges. This cost increase is a strong incentive to complete statistical recalibration of GRLWEAP dynamic capacity resistance value in a Phase 2 of this study. Title: Application of LRFD Geotechnical Principles for Pile Supported Bridges in Oregon: Phase 1 Author: Smith, Trevor D., Dusicka, Peter Year: 2009 Bridge foundations must be designed based on acceptable risks of failure. To secure rapid implementation of Load Resistance Factor Design (LRFD) principles for foundation design, the American Association of State Highway and Transportation Officials (AASHTO) and the Federal Highway Administration (FHWA) are requiring their use through AASHTO code. The Bridge Section of the Oregon Department of Transportation (ODOT) has responsibility for satisfactory design of all the bridge structures across the state’s highway system. The widespread geotechnical adoption of the LRFD code throughout state DOTs has been difficult in the case of deep foundations due to regional differences and in some cases a lack of any close match to DOT foundation practices. This lack of matching stems from the source research conducted on which the code is based, documented as NCHRP 507. For ODOT, the evaluation of nominal axial static capacity for each driven pile in the field is conducted by dynamic methods and AASHTO offers resistance factors for these techniques. ODOT typically uses the wave equation software (WEAP) applied at the end of initial driving, EOID, and occasionally at the beginning of pile restrike (BOR) to capture increases in capacity from set-up. This study reports that, based on past and new surveys, ODOT practice is reasonably typical for DOT practice in sands, silts, and clays. The AASHTO resistance factor, φ, for WEAP is at EOID and is too low for the efficient design of piles to match the likely probabilities of pile failure. The survey of Northwest state DOTs revealed that 80% of the DOTs believe that a φ of 0.4 is conservative and 37.5 % do not use the AASHTO-sanctioned φ of 0.4. Matching LRFD to allowable stress design (ASD) by direct calibration for a single pile, without any reported capacity bias, sets φ as 0.55 to match the ASD factor of safety of 2.5. An ODOT case history of a recently completed pilesupported bridge designed and constructed to FHWA and AASHTO ASD standards in use at that time, shows the number of piles at the bent studied would be doubled under new AASHTO requirements. This suggests the standard will add considerable pile foundation costs to all new bridges. This cost increase is a strong incentive to complete statistical recalibration of GRLWEAP dynamic capacity resistance value in a Phase 2 of this study. Close

• 11. [Article] Feasibility Determination Guide for the Road Diet Plus - A 5/4 Lane to 2 Lane Road Diet

  Road diets are a popular tool for corridor improvement. Road diets are normally defined as the conversion of a four-lane undivided road to a three-lane undivided road made up of two through lanes separated ...

  Citation × Citation Citation Abstract Copy Title: Feasibility Determination Guide for the Road Diet Plus - A 5/4 Lane to 2 Lane Road Diet Author: Williams, Michael Year: 2017 Road diets are a popular tool for corridor improvement. Road diets are normally defined as the conversion of a four-lane undivided road to a three-lane undivided road made up of two through lanes separated by a center two-way-left-turn-lane (known as a TWLTL). This new configuration has similar vehicular capacity, greater safety and frees up right-of-way for other uses. This work examines the possibility of going one step, or one lane, further. What is the possibility of reducing five- or four-lane roads to two-lanes? If this is possible, what are the corridor characteristics within which this process would be feasible? The transformation of five- or four-lane roads to two-lane roads becomes possible through the replacement of signalized and stop-controlled intersections with roundabouts. Roundabouts allow all left-hand turns along a street segment to be replaced with a U-turn at the roundabout followed by a right turn. With roundabouts, the TWLTL can be removed thereby creating a 2-lane road. Two major questions arise when determining the feasibility of this conversion. First, under what traffic conditions is this conversion possible? Second, does sufficient right-of-way exist for the conversion of standard intersections to roundabouts? This paper will examine corridors which have undergone this transformation to estimate the envelope within which this conversion is possible. It will provide estimates of the size of roundabouts for desired capacities and a traffic volume ceiling for the corridor. This work is limited to road diets resulting in corridors with two traffic lanes and single lane roundabouts. The final result of this work is a pamphlet similar to the 2014 FHWA Road Diet Informational Guide. The intent is to create a guide that accomplishes two goals. The first is to popularize a powerful strategy for roadway renovation. The second is to provide a tool that allows agencies to evaluate whether a chosen corridor is a possible candidate for this conversion. Title: Feasibility Determination Guide for the Road Diet Plus - A 5/4 Lane to 2 Lane Road Diet Author: Williams, Michael Year: 2017 Road diets are a popular tool for corridor improvement. Road diets are normally defined as the conversion of a four-lane undivided road to a three-lane undivided road made up of two through lanes separated by a center two-way-left-turn-lane (known as a TWLTL). This new configuration has similar vehicular capacity, greater safety and frees up right-of-way for other uses. This work examines the possibility of going one step, or one lane, further. What is the possibility of reducing five- or four-lane roads to two-lanes? If this is possible, what are the corridor characteristics within which this process would be feasible? The transformation of five- or four-lane roads to two-lane roads becomes possible through the replacement of signalized and stop-controlled intersections with roundabouts. Roundabouts allow all left-hand turns along a street segment to be replaced with a U-turn at the roundabout followed by a right turn. With roundabouts, the TWLTL can be removed thereby creating a 2-lane road. Two major questions arise when determining the feasibility of this conversion. First, under what traffic conditions is this conversion possible? Second, does sufficient right-of-way exist for the conversion of standard intersections to roundabouts? This paper will examine corridors which have undergone this transformation to estimate the envelope within which this conversion is possible. It will provide estimates of the size of roundabouts for desired capacities and a traffic volume ceiling for the corridor. This work is limited to road diets resulting in corridors with two traffic lanes and single lane roundabouts. The final result of this work is a pamphlet similar to the 2014 FHWA Road Diet Informational Guide. The intent is to create a guide that accomplishes two goals. The first is to popularize a powerful strategy for roadway renovation. The second is to provide a tool that allows agencies to evaluate whether a chosen corridor is a possible candidate for this conversion. Close

• 12. [Article] TMDLS: Statistical Correlations or Mechanistic Modeling?

  In developing TMDL waste-load allocations for the Snake River-Reservoir system in Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant ...

  Citation × Citation Citation Abstract Copy Title: TMDLS: Statistical Correlations or Mechanistic Modeling? Author: Wells, Scott A., Cole, Thomas M. Year: 2002 In developing TMDL waste-load allocations for the Snake River-Reservoir system in Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant reduction strategies has been performed using both a statistical-correlation approach and a mechanistic modeling approach. The system included the Lower Snake River, Brownlee Reservoir, Oxbow Reservoir, and Hells Canyon Reservoir with the focus was on Brownlee Reservoir. The statistical approach used on Brownlee Reservoir divided the system into riverine and lacustrine zones. Field data were then averaged over season and location to provide statistical correlations, such as between total phosphorus (TP) and chlorophyll a (chl a), between an anoxic factor (AF) and TP, and between a hypoxic factor (HP) and TP. The anoxic factor is defined as the number of days when dissolved oxygen was less than 2 mg/l and the hypoxic factor was defined as the number of days when dissolved oxygen was less than 6.5 mg/l. The mechanistic approach used a two-dimensional, unsteady, hydrodynamic and water quality model called CE-QUAL-W2. The model was calibrated to field data over a three year period for 1992 (a low flow year), 1995 (an average flow year), and 1997 (a high flow year). Some of the important questions that the TMDL process was to answer included the following. What level of TP is necessary in the river coming into Brownlee Reservoir to reduce the number of days of hypoxia in the reservoir? What are the causes of low-dissolved oxygen in Brownlee Reservoir and what management strategies can be implemented to improve water quality? This paper examines the strengths and weaknesses of answering management questions using these two approaches. Recommendations are suggested for answering assimilative capacity questions that arise in TMDL studies. Title: TMDLS: Statistical Correlations or Mechanistic Modeling? Author: Wells, Scott A., Cole, Thomas M. Year: 2002 In developing TMDL waste-load allocations for the Snake River-Reservoir system in Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant reduction strategies has been performed using both a statistical-correlation approach and a mechanistic modeling approach. The system included the Lower Snake River, Brownlee Reservoir, Oxbow Reservoir, and Hells Canyon Reservoir with the focus was on Brownlee Reservoir. The statistical approach used on Brownlee Reservoir divided the system into riverine and lacustrine zones. Field data were then averaged over season and location to provide statistical correlations, such as between total phosphorus (TP) and chlorophyll a (chl a), between an anoxic factor (AF) and TP, and between a hypoxic factor (HP) and TP. The anoxic factor is defined as the number of days when dissolved oxygen was less than 2 mg/l and the hypoxic factor was defined as the number of days when dissolved oxygen was less than 6.5 mg/l. The mechanistic approach used a two-dimensional, unsteady, hydrodynamic and water quality model called CE-QUAL-W2. The model was calibrated to field data over a three year period for 1992 (a low flow year), 1995 (an average flow year), and 1997 (a high flow year). Some of the important questions that the TMDL process was to answer included the following. What level of TP is necessary in the river coming into Brownlee Reservoir to reduce the number of days of hypoxia in the reservoir? What are the causes of low-dissolved oxygen in Brownlee Reservoir and what management strategies can be implemented to improve water quality? This paper examines the strengths and weaknesses of answering management questions using these two approaches. Recommendations are suggested for answering assimilative capacity questions that arise in TMDL studies. Close

• 13. [Article] A Numerical Solution For The Ultimate Strength of Tubular Beam-Columns

  To provide a basis for the development of interaction curves for tubular beam-columns of annular cross section, a general purpose beam-column computer program is developed, and used to determine ultimate ...

  Citation × Citation Citation Abstract Copy Title: A Numerical Solution For The Ultimate Strength of Tubular Beam-Columns Author: Wagner, Arnold L. Year: 1976 To provide a basis for the development of interaction curves for tubular beam-columns of annular cross section, a general purpose beam-column computer program is developed, and used to determine ultimate load capacities. The paper presents the analytical model and the computer method. The analytical results are compared with published test data as well as experimental data obtained as part of this project. Title: A Numerical Solution For The Ultimate Strength of Tubular Beam-Columns Author: Wagner, Arnold L. Year: 1976 To provide a basis for the development of interaction curves for tubular beam-columns of annular cross section, a general purpose beam-column computer program is developed, and used to determine ultimate load capacities. The paper presents the analytical model and the computer method. The analytical results are compared with published test data as well as experimental data obtained as part of this project. Close

• 14. [Article] Modeling Carrier Behavior in Sequential Auction Transportation Markets

  Online markets for transportation services, in the form of Internet sites that dynamically match shipments (shippers? demand) and transportation capacity (carriers? offer) through auction mechanisms are ...

  Citation × Citation Citation Abstract Copy Title: Modeling Carrier Behavior in Sequential Auction Transportation Markets Author: Figliozzi, Miguel Andres, Mahmassani, Hani S., Jaillet, Patrick Year: 2003 Online markets for transportation services, in the form of Internet sites that dynamically match shipments (shippers? demand) and transportation capacity (carriers? offer) through auction mechanisms are changing the traditional structure of transportation markets. A general framework for the study of carriers? behavior in a sequential auction transportation marketplace is provided. The unique characteristics of these marketplaces and the sources of difficulty in analyzing the behavior of these marketplaces are discussed. Learning and behavior in a sequential Vickrey auction marketplace is analyzed and simulated. Some results and the overall behavioral framework are also discussed. Title: Modeling Carrier Behavior in Sequential Auction Transportation Markets Author: Figliozzi, Miguel Andres, Mahmassani, Hani S., Jaillet, Patrick Year: 2003 Online markets for transportation services, in the form of Internet sites that dynamically match shipments (shippers? demand) and transportation capacity (carriers? offer) through auction mechanisms are changing the traditional structure of transportation markets. A general framework for the study of carriers? behavior in a sequential auction transportation marketplace is provided. The unique characteristics of these marketplaces and the sources of difficulty in analyzing the behavior of these marketplaces are discussed. Learning and behavior in a sequential Vickrey auction marketplace is analyzed and simulated. Some results and the overall behavioral framework are also discussed. Close

• 15. [Article] Seismic Retrofitting of Existing Structures

  This research project will give a brief presentation about earthquake resistant design and the methodology about seismic evaluation and rehabilitation of existing structures. It also provides certain aspects ...

  Citation × Citation Citation Abstract Copy Title: Seismic Retrofitting of Existing Structures Author: Sahin, Cetin Year: 2014 This research project will give a brief presentation about earthquake resistant design and the methodology about seismic evaluation and rehabilitation of existing structures. It also provides certain aspects of computer software modeling against seismic loads and shows the necessity of seismic upgrading in a steel moment-frame building. The seismic evaluation process consists of investigating if the structure meets the defined target structural performance levels. The main goal during earthquakes is to assure that building collapse doesn’t occur and the risk of death or injury to people is minimized and beyond that to satisfy post-earthquake performance level for defined range of of seismic hazards. Also seismic evaluation will determine which are the most vulnerable and weak components and deficiencies of a building during an expected earthquake. The seismic rehabilitation process aims to improve seismic performance and correct the deficiencies by increasing strength, stiffness or deformation capacity and improving connections. Thus, a proposed retrofit implementation can be said to be successful if it results an increase in strength and ductility capacity of the structure which is greater than the demands imposed by earthquakes. Performance-based design aims to utilize performance objectives to determine acceptable levels of damage for a given earthquake hazard for new buildings or upgrade of existing buildings. These performance objectives can be such as limiting story drift, minimizing component damage etc. This study shows how to model a building in computer software and analyze its seismic resistance with linear methods and propose concentrically braced frame rehabilitation in order to increase the drift capacity. It also describes how the linear analysis may be followed by the pushover analysis in order to estimate the seismic resistance of retrofitted structure. One of the most significant advantages of nonlinear pushover analysis beyond the linear analyses is the opportunity to evaluate damage. The pushover analysis can give valuable information about performance of building in expected future seismic events. Generally, the structural retrofit of concentrically braced frames improved the seismic resistance of the building and it can be considered in the retrofit of moment frame structures to prevent the risk of structural collapse under the design load with much more confidence. Title: Seismic Retrofitting of Existing Structures Author: Sahin, Cetin Year: 2014 This research project will give a brief presentation about earthquake resistant design and the methodology about seismic evaluation and rehabilitation of existing structures. It also provides certain aspects of computer software modeling against seismic loads and shows the necessity of seismic upgrading in a steel moment-frame building. The seismic evaluation process consists of investigating if the structure meets the defined target structural performance levels. The main goal during earthquakes is to assure that building collapse doesn’t occur and the risk of death or injury to people is minimized and beyond that to satisfy post-earthquake performance level for defined range of of seismic hazards. Also seismic evaluation will determine which are the most vulnerable and weak components and deficiencies of a building during an expected earthquake. The seismic rehabilitation process aims to improve seismic performance and correct the deficiencies by increasing strength, stiffness or deformation capacity and improving connections. Thus, a proposed retrofit implementation can be said to be successful if it results an increase in strength and ductility capacity of the structure which is greater than the demands imposed by earthquakes. Performance-based design aims to utilize performance objectives to determine acceptable levels of damage for a given earthquake hazard for new buildings or upgrade of existing buildings. These performance objectives can be such as limiting story drift, minimizing component damage etc. This study shows how to model a building in computer software and analyze its seismic resistance with linear methods and propose concentrically braced frame rehabilitation in order to increase the drift capacity. It also describes how the linear analysis may be followed by the pushover analysis in order to estimate the seismic resistance of retrofitted structure. One of the most significant advantages of nonlinear pushover analysis beyond the linear analyses is the opportunity to evaluate damage. The pushover analysis can give valuable information about performance of building in expected future seismic events. Generally, the structural retrofit of concentrically braced frames improved the seismic resistance of the building and it can be considered in the retrofit of moment frame structures to prevent the risk of structural collapse under the design load with much more confidence. Close

• 16. [Article] Definition and Properties of Alternative Bus Service Reliability Measures at the Stop Level

  The Transit Capacity and Quality of Service Manual (TCQSM) provides transit agencies with tools for measuring system performance at different levels of operation. Bus service reliability, one of the key ...

  Citation × Citation Citation Abstract Copy Title: Definition and Properties of Alternative Bus Service Reliability Measures at the Stop Level Author: Saberi, Meead, Zockaie, Ali K., Feng, Wei, El-Geneidy, Ahmed Year: 2013 The Transit Capacity and Quality of Service Manual (TCQSM) provides transit agencies with tools for measuring system performance at different levels of operation. Bus service reliability, one of the key performance measures, has become a major concern of both transit operators and users because it significantly affects user experience and service quality perceptions. The objective of this paper is to assess the existing reliability measures proposed by TCQSM and develop new ones at the bus stop level. The latter are not suggested as replacements for the existing measures; rather, they are complementary. Using empirical data from archived Bus Dispatch System (BDS) data in Portland, Oregon, a number of key characteristics of distributions of delay (schedule deviation) and headway deviation are identified. In addition, the proposed reliability measures at the stop level are capable of differentiating between the costs of being early versus late. The results of this study can be implemented in transit operations for use in improving schedules and operations strategies. Also, transit agencies can use the proposed reliability measures to evaluate and prioritize stops for operational improvement purposes. Title: Definition and Properties of Alternative Bus Service Reliability Measures at the Stop Level Author: Saberi, Meead, Zockaie, Ali K., Feng, Wei, El-Geneidy, Ahmed Year: 2013 The Transit Capacity and Quality of Service Manual (TCQSM) provides transit agencies with tools for measuring system performance at different levels of operation. Bus service reliability, one of the key performance measures, has become a major concern of both transit operators and users because it significantly affects user experience and service quality perceptions. The objective of this paper is to assess the existing reliability measures proposed by TCQSM and develop new ones at the bus stop level. The latter are not suggested as replacements for the existing measures; rather, they are complementary. Using empirical data from archived Bus Dispatch System (BDS) data in Portland, Oregon, a number of key characteristics of distributions of delay (schedule deviation) and headway deviation are identified. In addition, the proposed reliability measures at the stop level are capable of differentiating between the costs of being early versus late. The results of this study can be implemented in transit operations for use in improving schedules and operations strategies. Also, transit agencies can use the proposed reliability measures to evaluate and prioritize stops for operational improvement purposes. Close

• 17. [Article] Vehicle Routing Problem for Emissions Minimization

  Environmental, social, and political pressures to limit the effects associated with greenhouse gas emissions are mounting. Little research has been done on reducing emissions as the primary objective of ...

  Citation × Citation Citation Abstract Copy Title: Vehicle Routing Problem for Emissions Minimization Author: Figliozzi, Miguel Year: 2010 Environmental, social, and political pressures to limit the effects associated with greenhouse gas emissions are mounting. Little research has been done on reducing emissions as the primary objective of a routing problem despite the growth in use and impact of commercial vehicles. In the capacitated vehicle routing problem (VRP) with time windows, it is traditionally assumed that carriers minimize the number of vehicles as a primary objective and distance traveled as a secondary objective without violating time windows, route durations, or capacity constraints. New research focuses on a different problem: the minimization of emissions and fuel consumption as the primary or secondary objective. This creates the emissions VRP (EVRP). A formulation and solution approaches for the EVRP are presented. Decision variables and properties are stated and discussed. Results obtained with a proposed EVRP solution approach for different levels of congestion are compared and analyzed. Title: Vehicle Routing Problem for Emissions Minimization Author: Figliozzi, Miguel Year: 2010 Environmental, social, and political pressures to limit the effects associated with greenhouse gas emissions are mounting. Little research has been done on reducing emissions as the primary objective of a routing problem despite the growth in use and impact of commercial vehicles. In the capacitated vehicle routing problem (VRP) with time windows, it is traditionally assumed that carriers minimize the number of vehicles as a primary objective and distance traveled as a secondary objective without violating time windows, route durations, or capacity constraints. New research focuses on a different problem: the minimization of emissions and fuel consumption as the primary or secondary objective. This creates the emissions VRP (EVRP). A formulation and solution approaches for the EVRP are presented. Decision variables and properties are stated and discussed. Results obtained with a proposed EVRP solution approach for different levels of congestion are compared and analyzed. Close

• 18. [Article] A Coordinated Location-Inventory Problem in Closed-Loop Supply Chain

  This paper considers a coordinated location-inventory model under uncertain demands for a closed loop supply chain comprising of one plant, forward and reverse distribution centers, and retailers. The ...

  Citation × Citation Citation Abstract Copy Title: A Coordinated Location-Inventory Problem in Closed-Loop Supply Chain Author: Zhang, Zhi-Hai, Unnikrishnan, Avinash Year: 2016 This paper considers a coordinated location-inventory model under uncertain demands for a closed loop supply chain comprising of one plant, forward and reverse distribution centers, and retailers. The inventory of new and returned products is managed at forward and reverse distribution centers respectively through a periodic review policy. The proposed model determines the location of forward and reverse distribution centers and the associated capacities, the review intervals of the inventory policy at distribution centers, and the assignments of retailers to the distribution centers. We model six different coordination strategies. All the models are formulated as nonlinear integer programs with chance constraints and transformed to conic quadratic mixed-integer programs that can be efficiently solved by CPLEX. An outer approximation based solution algorithm is developed to solve the conic quadratic mixed-integer program. The benefit of different types of coordination strategies is shown through extensive computational testing. Title: A Coordinated Location-Inventory Problem in Closed-Loop Supply Chain Author: Zhang, Zhi-Hai, Unnikrishnan, Avinash Year: 2016 This paper considers a coordinated location-inventory model under uncertain demands for a closed loop supply chain comprising of one plant, forward and reverse distribution centers, and retailers. The inventory of new and returned products is managed at forward and reverse distribution centers respectively through a periodic review policy. The proposed model determines the location of forward and reverse distribution centers and the associated capacities, the review intervals of the inventory policy at distribution centers, and the assignments of retailers to the distribution centers. We model six different coordination strategies. All the models are formulated as nonlinear integer programs with chance constraints and transformed to conic quadratic mixed-integer programs that can be efficiently solved by CPLEX. An outer approximation based solution algorithm is developed to solve the conic quadratic mixed-integer program. The benefit of different types of coordination strategies is shown through extensive computational testing. Close

• 19. [Article] Framework for Study of Carrier Strategies in Auction-Based Transportation Marketplace

  Online markets for transportation services in the form of Internet sites that dynamically match shipments (shippers' demand) and transportation capacity (carriers' offer) through auction mechanisms are ...

  Citation × Citation Citation Abstract Copy Title: Framework for Study of Carrier Strategies in Auction-Based Transportation Marketplace Author: Figliozzi, Miguel, Mahmassani, Hani, Jaillet, Patrick Year: 2003 Online markets for transportation services in the form of Internet sites that dynamically match shipments (shippers' demand) and transportation capacity (carriers' offer) through auction mechanisms are changing the traditional structure of transportation markets. A general framework for the study of carriers' strategies in a transportation auction market place is provided. The unique characteristics of these marketplaces and the sources of difficulty in analyzing the performance of these market places under different carrier bidding strategies are discussed. A simulation framework is used to explore the complex engineering and economic processes and issues that arise in a transportation marketplace and that are difficult to explore by using standard analytical or statistical tools. Some results and the overall simulation framework are also discussed. Title: Framework for Study of Carrier Strategies in Auction-Based Transportation Marketplace Author: Figliozzi, Miguel, Mahmassani, Hani, Jaillet, Patrick Year: 2003 Online markets for transportation services in the form of Internet sites that dynamically match shipments (shippers' demand) and transportation capacity (carriers' offer) through auction mechanisms are changing the traditional structure of transportation markets. A general framework for the study of carriers' strategies in a transportation auction market place is provided. The unique characteristics of these marketplaces and the sources of difficulty in analyzing the performance of these market places under different carrier bidding strategies are discussed. A simulation framework is used to explore the complex engineering and economic processes and issues that arise in a transportation marketplace and that are difficult to explore by using standard analytical or statistical tools. Some results and the overall simulation framework are also discussed. Close

• 20. [Article] Planning Approximations to the Average Length of Vehicle Routing Problems with Time Window Constraints

  This paper studies approximations to the average length of vehicle routing problems (VRP) with time window, route duration, and capacity constraints. The approximations are valuable for the strategic and ...

  Citation × Citation Citation Abstract Copy Title: Planning Approximations to the Average Length of Vehicle Routing Problems with Time Window Constraints Author: Figliozzi, Miguel Year: 2009 This paper studies approximations to the average length of vehicle routing problems (VRP) with time window, route duration, and capacity constraints. The approximations are valuable for the strategic and planning analysis of transportation and logistics problems. Using asymptotic properties of vehicle routing problems and the average probability of successfully sequencing a customer with time windows a new expression to estimate VRP distances is developed. The increase in the number of routes when time constraints are added is modeled probabilistically. This paper introduces the concept of the average probability of successfully sequencing a customer with time windows. It is proven that this average probability is a unique characteristic of a vehicle routing problem. The approximation proposed is tested in instances with different customer spatial distributions, depot locations and number of customers. Regression results indicate that the proposed approximation is not only intuitive but also predicts the average length of VRP problems with a high level of accuracy. Title: Planning Approximations to the Average Length of Vehicle Routing Problems with Time Window Constraints Author: Figliozzi, Miguel Year: 2009 This paper studies approximations to the average length of vehicle routing problems (VRP) with time window, route duration, and capacity constraints. The approximations are valuable for the strategic and planning analysis of transportation and logistics problems. Using asymptotic properties of vehicle routing problems and the average probability of successfully sequencing a customer with time windows a new expression to estimate VRP distances is developed. The increase in the number of routes when time constraints are added is modeled probabilistically. This paper introduces the concept of the average probability of successfully sequencing a customer with time windows. It is proven that this average probability is a unique characteristic of a vehicle routing problem. The approximation proposed is tested in instances with different customer spatial distributions, depot locations and number of customers. Regression results indicate that the proposed approximation is not only intuitive but also predicts the average length of VRP problems with a high level of accuracy. Close

• 21. [Article] Behavior of Reinforced Concrete Beams Retrofitted in Flexure Using CFRP-NSM Technique

  A variety of retrofitting methods are used to upgrade existing structures. For example, steel plates and Fiber Reinforced Polymer (FRP) jackets are externally bonded to members to increase their capacity ...

  Citation × Citation Citation Abstract Copy Title: Behavior of Reinforced Concrete Beams Retrofitted in Flexure Using CFRP-NSM Technique Author: Al-Obaidi, Salam Year: 2015 A variety of retrofitting methods are used to upgrade existing structures. For example, steel plates and Fiber Reinforced Polymer (FRP) jackets are externally bonded to members to increase their capacity in flexure and shear. However, due to the issue of corrosion these strengthening systems may lose their efficiency with time. FRP materials have been used to strengthen many structural components of different shapes and types. FRP jackets, FRP Strips, and FRP rods have commonly been used to rehabilitate existing structural components. The many advantages of using FRP as strengthening materials have made this material an attractive alternative: advantages such as lightweight, high strength, and ease of setting up. Among the many applications using FRP, Near Surface Mounted -- Fiber Reinforced polymer (NSM-FRP) is a promising technique used to strengthen concrete members. However, de-bonding issues have to be overcome to make this technique efficient and reliable. The NSM-FRP technique consists of making a groove along the surface of the concrete member to be retrofitted with depth less than the cover of the member. After cleaning the groove, epoxy paste is used to fill two-thirds of the groove's depth. The FRP element is then mounted in the groove. Finally, the groove is filled with epoxy and the excessive epoxy is leveled with surface of the concrete. This technique makes the FRP material completely covered by epoxy in the cover of the concrete. This method can be used for strengthening both the positive and negative moment regions of girders and slabs. Groove size, paste, concrete, and rods properties are the main variables that control the efficiency of the NSM-FRP rods. The main objective of this research project is to determine the behavior of reinforced concrete beams that are strengthened with NSM-CFRP reinforcement bars. In this research project, the bond characteristics of NSM-CFRP reinforcement bars are first determined from pullout tests. Then, NSM-CFRP rods are installed in reinforced concrete beams and the beams are tested. Loads, strains, and deflections are measured and theoretical and measured capacities are compared. Finally, the reliability and efficiency of using NSM-CFRP rods technique in retrofitting existing structures is observed. Title: Behavior of Reinforced Concrete Beams Retrofitted in Flexure Using CFRP-NSM Technique Author: Al-Obaidi, Salam Year: 2015 A variety of retrofitting methods are used to upgrade existing structures. For example, steel plates and Fiber Reinforced Polymer (FRP) jackets are externally bonded to members to increase their capacity in flexure and shear. However, due to the issue of corrosion these strengthening systems may lose their efficiency with time. FRP materials have been used to strengthen many structural components of different shapes and types. FRP jackets, FRP Strips, and FRP rods have commonly been used to rehabilitate existing structural components. The many advantages of using FRP as strengthening materials have made this material an attractive alternative: advantages such as lightweight, high strength, and ease of setting up. Among the many applications using FRP, Near Surface Mounted -- Fiber Reinforced polymer (NSM-FRP) is a promising technique used to strengthen concrete members. However, de-bonding issues have to be overcome to make this technique efficient and reliable. The NSM-FRP technique consists of making a groove along the surface of the concrete member to be retrofitted with depth less than the cover of the member. After cleaning the groove, epoxy paste is used to fill two-thirds of the groove's depth. The FRP element is then mounted in the groove. Finally, the groove is filled with epoxy and the excessive epoxy is leveled with surface of the concrete. This technique makes the FRP material completely covered by epoxy in the cover of the concrete. This method can be used for strengthening both the positive and negative moment regions of girders and slabs. Groove size, paste, concrete, and rods properties are the main variables that control the efficiency of the NSM-FRP rods. The main objective of this research project is to determine the behavior of reinforced concrete beams that are strengthened with NSM-CFRP reinforcement bars. In this research project, the bond characteristics of NSM-CFRP reinforcement bars are first determined from pullout tests. Then, NSM-CFRP rods are installed in reinforced concrete beams and the beams are tested. Loads, strains, and deflections are measured and theoretical and measured capacities are compared. Finally, the reliability and efficiency of using NSM-CFRP rods technique in retrofitting existing structures is observed. Close

• 22. [Article] Bridge Damage Models for Seismic Risk Assessment of Oregon Highway Network

  The highway transportation network of the United States relies on the health and integrity of major infrastructure elements such as bridges. Frequently traveled parts of Oregon are within the seismically ...

  Citation × Citation Citation Abstract Copy Title: Bridge Damage Models for Seismic Risk Assessment of Oregon Highway Network Author: Dusicka, Peter, Roberts, Jeffery Year: 2011 The highway transportation network of the United States relies on the health and integrity of major infrastructure elements such as bridges. Frequently traveled parts of Oregon are within the seismically active Pacific Northwest and many of the bridges were designed and built to lateral demands that were assumed to be less than the current expectation, a deficiency caused by our growing awareness of seismic hazard and our enhanced understanding of the non-linear response of bridges. This vulnerability to damage from earthquakes can result in not only immediate damage, but also in potentially lingering economic impact caused by the disruption to traffic and freight mobility. Using analytical methods, fragility curves were constructed assuming lognormal capacity and demand distributions. Probability of failure was determined for the four damage state conditions of slight, moderate, extensive, and complete levels of damage. These statistical values were compared to the median and dispersion values proposed by other researchers, in addition to those calculated using guidelines from the HAZUS Technical Manual. Older multiple-span Oregon bridges were found to be significantly more fragile than the HAZUS models. As a result of this modeling and analysis effort, the relative fragility of the modeled typical 3-span and 5-span bridges was determined and quantified. Possible causes of the relatively high fragilities were also considered. Title: Bridge Damage Models for Seismic Risk Assessment of Oregon Highway Network Author: Dusicka, Peter, Roberts, Jeffery Year: 2011 The highway transportation network of the United States relies on the health and integrity of major infrastructure elements such as bridges. Frequently traveled parts of Oregon are within the seismically active Pacific Northwest and many of the bridges were designed and built to lateral demands that were assumed to be less than the current expectation, a deficiency caused by our growing awareness of seismic hazard and our enhanced understanding of the non-linear response of bridges. This vulnerability to damage from earthquakes can result in not only immediate damage, but also in potentially lingering economic impact caused by the disruption to traffic and freight mobility. Using analytical methods, fragility curves were constructed assuming lognormal capacity and demand distributions. Probability of failure was determined for the four damage state conditions of slight, moderate, extensive, and complete levels of damage. These statistical values were compared to the median and dispersion values proposed by other researchers, in addition to those calculated using guidelines from the HAZUS Technical Manual. Older multiple-span Oregon bridges were found to be significantly more fragile than the HAZUS models. As a result of this modeling and analysis effort, the relative fragility of the modeled typical 3-span and 5-span bridges was determined and quantified. Possible causes of the relatively high fragilities were also considered. Close

• 23. [Article] Experimental Investigation of Fiber Reinforced Concrete Beams

  Shear strength of fiber reinforced concrete beams was studied in this research project. Three types of fibers were examined: hooked-end steel fiber, crimped-steel fiber, and crimped-monofilament polypropylene ...

  Citation × Citation Citation Abstract Copy Title: Experimental Investigation of Fiber Reinforced Concrete Beams Author: Al-lami, Karrar Ali Year: 2015 Shear strength of fiber reinforced concrete beams was studied in this research project. Three types of fibers were examined: hooked-end steel fiber, crimped-steel fiber, and crimped-monofilament polypropylene fibers. The experimental program included five beam specimens. Two of the beams were control specimens in which one was reinforced with minimum shear reinforcement according to ACI 318, while the other one did not have any shear reinforcement. Each one of the other three specimens was reinforced with one of the above mentioned fibers by 1% volumetric ratio. In addition to the beam specimens, three prisms were also made for each type fiber to determine their toughness. The aim of this research was to investigate the following questions for medium-high concrete strength 1) to evaluate the effectiveness of each type of fibers on the shear strength, 2) to investigate the shear strength, toughness, crack patterns and near ultimate load crack width of each beam, and 3) to determine if using 1% volumetric ratio of fibers as shear reinforcement in beams would provide adequate strength and stiffness properties comparable to reinforcing steel used as minimum shear reinforcement. The results showed that all three types of fibers increased the shear capacity of the beam specimens more than the beam reinforced with minimum shear reinforcement. Moreover, some of the fibers used could shift the type of failure from a pure shear failure to a combined flexural-shear or pure flexural failure. Title: Experimental Investigation of Fiber Reinforced Concrete Beams Author: Al-lami, Karrar Ali Year: 2015 Shear strength of fiber reinforced concrete beams was studied in this research project. Three types of fibers were examined: hooked-end steel fiber, crimped-steel fiber, and crimped-monofilament polypropylene fibers. The experimental program included five beam specimens. Two of the beams were control specimens in which one was reinforced with minimum shear reinforcement according to ACI 318, while the other one did not have any shear reinforcement. Each one of the other three specimens was reinforced with one of the above mentioned fibers by 1% volumetric ratio. In addition to the beam specimens, three prisms were also made for each type fiber to determine their toughness. The aim of this research was to investigate the following questions for medium-high concrete strength 1) to evaluate the effectiveness of each type of fibers on the shear strength, 2) to investigate the shear strength, toughness, crack patterns and near ultimate load crack width of each beam, and 3) to determine if using 1% volumetric ratio of fibers as shear reinforcement in beams would provide adequate strength and stiffness properties comparable to reinforcing steel used as minimum shear reinforcement. The results showed that all three types of fibers increased the shear capacity of the beam specimens more than the beam reinforced with minimum shear reinforcement. Moreover, some of the fibers used could shift the type of failure from a pure shear failure to a combined flexural-shear or pure flexural failure. Close

• 24. [Article] Trace Metals in Stormwater: Alternative Best Management Practices

  Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate ...

  Citation × Citation Citation Abstract Copy Title: Trace Metals in Stormwater: Alternative Best Management Practices Author: Mora, Jennifer Ibeth Year: 2017 Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate the heavy metal (Cu and Zn) removal efficiency of perlite and EarthliteTM to improve in-situ filtration systems for stormwater catchment basins. Stormwater samples from two field sites in Portland, OR, chosen to represent a high-use commercial site and high-traffic urban road, were characterized to inform experimental design and compare to values found in literature. The Linear, Freundlich, and Langmuir isotherm models were used to describe equilibrium data and determine partitioning coefficients for single metal batch studies. Both the Freundlich and Langmuir models fit most single metal batch systems, while Cu-Perlite, Zn-Perlite, and Zn-EarthliteTM, were best fit by the Langmuir model, R2 = 0.9594; 0.9538; 0.9811, respectively. Competitive adsorption behaviors for Cu and Zn were evaluated using a synthetic stormwater recipe where relative concentrations of Cu and Zn were maintained to be consistent with representative stormwater samples. Perlite showed a decrease in the sorption capacity of Cu and Zn in the presence of competing ions in solution. EarthliteTM showed no difference in the affinity for copper uptake between competitive and non-competitive batch experiments. EarthliteTM affinity for Zn decreased by two orders of magnitude in the competitive batch system. The results from this study will be applied to estimate filter lifetime for traditional and advanced stormwater filter systems. These results will inform experimental design in dynamic flow-through experiments using various filter media thereby improving filter design and implementation of stormwater best management practices. Title: Trace Metals in Stormwater: Alternative Best Management Practices Author: Mora, Jennifer Ibeth Year: 2017 Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate the heavy metal (Cu and Zn) removal efficiency of perlite and EarthliteTM to improve in-situ filtration systems for stormwater catchment basins. Stormwater samples from two field sites in Portland, OR, chosen to represent a high-use commercial site and high-traffic urban road, were characterized to inform experimental design and compare to values found in literature. The Linear, Freundlich, and Langmuir isotherm models were used to describe equilibrium data and determine partitioning coefficients for single metal batch studies. Both the Freundlich and Langmuir models fit most single metal batch systems, while Cu-Perlite, Zn-Perlite, and Zn-EarthliteTM, were best fit by the Langmuir model, R2 = 0.9594; 0.9538; 0.9811, respectively. Competitive adsorption behaviors for Cu and Zn were evaluated using a synthetic stormwater recipe where relative concentrations of Cu and Zn were maintained to be consistent with representative stormwater samples. Perlite showed a decrease in the sorption capacity of Cu and Zn in the presence of competing ions in solution. EarthliteTM showed no difference in the affinity for copper uptake between competitive and non-competitive batch experiments. EarthliteTM affinity for Zn decreased by two orders of magnitude in the competitive batch system. The results from this study will be applied to estimate filter lifetime for traditional and advanced stormwater filter systems. These results will inform experimental design in dynamic flow-through experiments using various filter media thereby improving filter design and implementation of stormwater best management practices. Close

• 25. [Article] Multi-Model Ensemble Analysis of Runoff Extremes for Climate Change Impact Assessments

  In this study multi-model ensemble analysis of extreme runoff is performed based on eight regional climate models (RCMs) provided by the North American Regional Climate Change Assessment Program (NARCCAP). ...

  Citation × Citation Citation Abstract Copy Title: Multi-Model Ensemble Analysis of Runoff Extremes for Climate Change Impact Assessments Author: Najafi, Mohammad Reza, Moradkhani, Hamid Year: 2015 In this study multi-model ensemble analysis of extreme runoff is performed based on eight regional climate models (RCMs) provided by the North American Regional Climate Change Assessment Program (NARCCAP). Hydrologic simulation is performed by driving the Variable Infiltration Capacity (VIC) model over the Pacific Northwest region, for historical and future time periods. Extreme event analysis is then conducted using spatial hierarchical Bayesian modeling (SHB). Ensemble merging of extreme runoff is carried out using Bayesian Model Averaging (BMA) in which spatially distributed weights corresponding to each regional climate model are obtained. Comparison of the residuals before and after the multi-model combination shows that the merged signal generally outperforms the best individual signal. The climate model simulations show close performance regarding maximum and minimum temperature and wind speed, however, the differences are more pronounced for precipitation and runoff. Between-model variances increase for the future time series compared to the historical ones indicating larger uncertainties in climate change projections. The combined model is then used to predict projected seasonal runoff extremes and compare them with historical simulations. Ensemble average results suggest that seasonal extreme runoff will increase in most regions in particular the Rockies and west of the Cascades. Title: Multi-Model Ensemble Analysis of Runoff Extremes for Climate Change Impact Assessments Author: Najafi, Mohammad Reza, Moradkhani, Hamid Year: 2015 In this study multi-model ensemble analysis of extreme runoff is performed based on eight regional climate models (RCMs) provided by the North American Regional Climate Change Assessment Program (NARCCAP). Hydrologic simulation is performed by driving the Variable Infiltration Capacity (VIC) model over the Pacific Northwest region, for historical and future time periods. Extreme event analysis is then conducted using spatial hierarchical Bayesian modeling (SHB). Ensemble merging of extreme runoff is carried out using Bayesian Model Averaging (BMA) in which spatially distributed weights corresponding to each regional climate model are obtained. Comparison of the residuals before and after the multi-model combination shows that the merged signal generally outperforms the best individual signal. The climate model simulations show close performance regarding maximum and minimum temperature and wind speed, however, the differences are more pronounced for precipitation and runoff. Between-model variances increase for the future time series compared to the historical ones indicating larger uncertainties in climate change projections. The combined model is then used to predict projected seasonal runoff extremes and compare them with historical simulations. Ensemble average results suggest that seasonal extreme runoff will increase in most regions in particular the Rockies and west of the Cascades. Close

• 26. [Article] Factors Influencing Effectiveness of Transit Signal Priority and Late-Bus Recovery at Signalized-Intersection Level

  Transit priority systems have the potential to improve transit performance and address capacity constraints by giving priority to transit movements over other traffic. This research focused on the effectiveness ...

  Citation × Citation Citation Abstract Copy Title: Factors Influencing Effectiveness of Transit Signal Priority and Late-Bus Recovery at Signalized-Intersection Level Author: Albright, Eric, Figliozzi, Miguel A. Year: 2012 Transit priority systems have the potential to improve transit performance and address capacity constraints by giving priority to transit movements over other traffic. This research focused on the effectiveness of conditional transit priority or the manipulation of traffic signal timing plans to reduce delay of late transit buses. The integration of two transportation subsystems—traffic signals and public transit systems—was studied. These subsystems interact along a congested corridor where they share a common roadway infrastructure and transit signal priority (TSP) regulates the interaction between traffic signals, passenger traffic, and buses. Previous research has focused on the evaluation of bus TSP performance at the route level. In practice, it is important to understand not only TSP performance at the route level but also the impact of TSP at the level of the traffic signal intersection (e.g., to allow progression in major cross streets). TSP can significantly improve performance at specific intersections, even though at the route level TSP shows a more modest impact. This study proposed the integration of several data sets such as bus scheduling and location, passenger flows, and TSP requests to evaluate schedule adherence at the stop level and TSP performance at the level of the signalized intersection. A congested arterial corridor was analyzed and regression analysis was used to determine the key factors that affect bus travel time and schedule recovery for late buses. TSP was found to be most effective at lower-volume intersections where queuing was less problematic. Implications of the findings are analyzed and discussed. Title: Factors Influencing Effectiveness of Transit Signal Priority and Late-Bus Recovery at Signalized-Intersection Level Author: Albright, Eric, Figliozzi, Miguel A. Year: 2012 Transit priority systems have the potential to improve transit performance and address capacity constraints by giving priority to transit movements over other traffic. This research focused on the effectiveness of conditional transit priority or the manipulation of traffic signal timing plans to reduce delay of late transit buses. The integration of two transportation subsystems—traffic signals and public transit systems—was studied. These subsystems interact along a congested corridor where they share a common roadway infrastructure and transit signal priority (TSP) regulates the interaction between traffic signals, passenger traffic, and buses. Previous research has focused on the evaluation of bus TSP performance at the route level. In practice, it is important to understand not only TSP performance at the route level but also the impact of TSP at the level of the traffic signal intersection (e.g., to allow progression in major cross streets). TSP can significantly improve performance at specific intersections, even though at the route level TSP shows a more modest impact. This study proposed the integration of several data sets such as bus scheduling and location, passenger flows, and TSP requests to evaluate schedule adherence at the stop level and TSP performance at the level of the signalized intersection. A congested arterial corridor was analyzed and regression analysis was used to determine the key factors that affect bus travel time and schedule recovery for late buses. TSP was found to be most effective at lower-volume intersections where queuing was less problematic. Implications of the findings are analyzed and discussed. Close

• 27. [Article] Achieving Operational Seismic Performance of RC Bridge Bents Retrofitted With Buckling-Restrained Braces

  Typical reinforced concrete (RC) bridges built prior to 1970 were designed with minimum seismic consideration, leaving numerous bridges highly susceptible to damage following an earthquake. In order to ...

  Citation × Citation Citation Abstract Copy Title: Achieving Operational Seismic Performance of RC Bridge Bents Retrofitted With Buckling-Restrained Braces Author: Bazáez Gallardo, Ramiro Andrés Gabriel Year: 2017 Typical reinforced concrete (RC) bridges built prior to 1970 were designed with minimum seismic consideration, leaving numerous bridges highly susceptible to damage following an earthquake. In order to improve the seismic behavior of substandard RC bridges, this study presents the seismic performance of reinforced concrete bridge bents retrofitted and repaired using Buckling-Restrained Braces (BRBs) while considering subduction zone earthquake demands. In order to reflect displacement demands from subduction ground motions, research studies were conducted to develop quasi-static loading protocols and then investigate their effect on structural bridge damage. Results suggested that subduction loading protocols may reduce the displacement ductility capacity of RC bridge columns and change their failure mode. The cyclic performance of reinforced concrete bridge bents retrofitted and repaired using BRBs was experimentally evaluated using large-scale specimens and the developed loading histories. Three BRB specimens were evaluated with the aim of assessing the influence of these components on the overall performance of the retrofitted and repaired bents. Additionally, subassemblage tests were conducted in an effort to study the response of these elements and to allow for refined nonlinear characterization in the analysis of the retrofitted and repaired systems. The results of the large-scale experiments and analytical studies successfully demonstrated the effectiveness of utilizing buckling-restrained braces for achieving high displacement ductility of the retrofitted and repaired structures, while also controlling the damage of the existing vulnerable reinforced concrete bent up to an operational performance level. Title: Achieving Operational Seismic Performance of RC Bridge Bents Retrofitted With Buckling-Restrained Braces Author: Bazáez Gallardo, Ramiro Andrés Gabriel Year: 2017 Typical reinforced concrete (RC) bridges built prior to 1970 were designed with minimum seismic consideration, leaving numerous bridges highly susceptible to damage following an earthquake. In order to improve the seismic behavior of substandard RC bridges, this study presents the seismic performance of reinforced concrete bridge bents retrofitted and repaired using Buckling-Restrained Braces (BRBs) while considering subduction zone earthquake demands. In order to reflect displacement demands from subduction ground motions, research studies were conducted to develop quasi-static loading protocols and then investigate their effect on structural bridge damage. Results suggested that subduction loading protocols may reduce the displacement ductility capacity of RC bridge columns and change their failure mode. The cyclic performance of reinforced concrete bridge bents retrofitted and repaired using BRBs was experimentally evaluated using large-scale specimens and the developed loading histories. Three BRB specimens were evaluated with the aim of assessing the influence of these components on the overall performance of the retrofitted and repaired bents. Additionally, subassemblage tests were conducted in an effort to study the response of these elements and to allow for refined nonlinear characterization in the analysis of the retrofitted and repaired systems. The results of the large-scale experiments and analytical studies successfully demonstrated the effectiveness of utilizing buckling-restrained braces for achieving high displacement ductility of the retrofitted and repaired structures, while also controlling the damage of the existing vulnerable reinforced concrete bent up to an operational performance level. Close

• 28. [Article] Exploring High-Resolution Data Obtained from ASC/3 Controller of Intersection SE Division St & SE 122nd Ave, Portland, Oregon.

  High-resolution data obtained from ASC/3 controllers can be used to create a variety of performance measures, helping engineers and professionals in monitoring intersection performance, identifying issues, ...

  Citation × Citation Citation Abstract Copy Title: Exploring High-Resolution Data Obtained from ASC/3 Controller of Intersection SE Division St & SE 122nd Ave, Portland, Oregon. Author: Al-Abbas, Naowar Year: 2018 High-resolution data obtained from ASC/3 controllers can be used to create a variety of performance measures, helping engineers and professionals in monitoring intersection performance, identifying issues, and making proper improvements. These measures concern the intersection quality of the progression, capacity, and non-vehicular operations (e.g. pedestrian crossings). In this report, we explored high-resolution data obtained from the intersection of SE Division Street and 122nd Avenue. This intersection had some safety concerns as it is considered one of most dangerous intersections in Portland, Oregon. Thus, the first variable we examined from the data was pedestrian wait time when a cross request is made until pass indication is shown. It was found around 60% of pedestrians who crossed in an east-west direction experienced a delay of 30 seconds or more. Although there was more pedestrian demand from the south to west direction, 70% of these pedestrians received a 30 second delay or longer. Delay values determined from controller data in this report only refer to pedestrians who made a request/call to cross at a particular direction in each cycle. Additionally, an alternate means of calculating actual pedestrian delay was also addressed. The other part of the analysis regarded vehicle operations and signal indications. Green time, cycle length, green-to-cycle ratio, and vehicle count per each cycle were all explored. Furthermore, the quality of the progression of coordinated phases of the through vehicular movement on SE division was quantitatively examined using the proportion of vehicles that had arrived during green indication and Arrival Type (AT), and visually, using the Purdue Coordination Diagram (PCD). The results showed that quality of progression was in good standard. Finally, errors found in the data and the accuracy of the results were also addressed. Title: Exploring High-Resolution Data Obtained from ASC/3 Controller of Intersection SE Division St & SE 122nd Ave, Portland, Oregon. Author: Al-Abbas, Naowar Year: 2018 High-resolution data obtained from ASC/3 controllers can be used to create a variety of performance measures, helping engineers and professionals in monitoring intersection performance, identifying issues, and making proper improvements. These measures concern the intersection quality of the progression, capacity, and non-vehicular operations (e.g. pedestrian crossings). In this report, we explored high-resolution data obtained from the intersection of SE Division Street and 122nd Avenue. This intersection had some safety concerns as it is considered one of most dangerous intersections in Portland, Oregon. Thus, the first variable we examined from the data was pedestrian wait time when a cross request is made until pass indication is shown. It was found around 60% of pedestrians who crossed in an east-west direction experienced a delay of 30 seconds or more. Although there was more pedestrian demand from the south to west direction, 70% of these pedestrians received a 30 second delay or longer. Delay values determined from controller data in this report only refer to pedestrians who made a request/call to cross at a particular direction in each cycle. Additionally, an alternate means of calculating actual pedestrian delay was also addressed. The other part of the analysis regarded vehicle operations and signal indications. Green time, cycle length, green-to-cycle ratio, and vehicle count per each cycle were all explored. Furthermore, the quality of the progression of coordinated phases of the through vehicular movement on SE division was quantitatively examined using the proportion of vehicles that had arrived during green indication and Arrival Type (AT), and visually, using the Purdue Coordination Diagram (PCD). The results showed that quality of progression was in good standard. Finally, errors found in the data and the accuracy of the results were also addressed. Close

• 29. [Article] Laurance Lake Temperature Model

  Laurance Lake is a reservoir located in Hood River County, Oregon (Figure 1). It is located at the base on Mt. Hood in Oregon (see Figure 2 and Figure 3), discharges into the Middle Fork of the Hood River. ...

  Citation × Citation Citation Abstract Copy Title: Laurance Lake Temperature Model Author: Berger, Chris, Wells, Scott A., Annear, Robert Leslie Year: 2005 Laurance Lake is a reservoir located in Hood River County, Oregon (Figure 1). It is located at the base on Mt. Hood in Oregon (see Figure 2 and Figure 3), discharges into the Middle Fork of the Hood River. The reservoir was constructed in 1968 for irrigation storage and has a capacity 3564 acre- feet at full pool. Since the river vio lates temperature standards, this study has been designed to construct a hydrodynamic and temperature model of Laurance reservoir in order to assess strategies for improving temperatures in the Middle Fork River. The objectives of the study are then to Develop a hydrodynamic and temperature model of Laurance Lake Calibrate the model to field data collected from November 2002 through Spring 2004 Use the model to evaluate strategies for temperature improvement through operational or structural changes to Lake Laurance The model chosen for development was CE-QUAL-W2 Version 3.2 (Cole and Wells, 2004). This is a two-dimensional unsteady hydrodynamic, temperature and water quality model that includes typical eutrophication parameters (algae, nutrients, temperature, organic matter, dissolved oxygen, pH). PSU, under the support of the Corps of Engineers Waterways Experiment Station, is a center for development of this modeling tool. Title: Laurance Lake Temperature Model Author: Berger, Chris, Wells, Scott A., Annear, Robert Leslie Year: 2005 Laurance Lake is a reservoir located in Hood River County, Oregon (Figure 1). It is located at the base on Mt. Hood in Oregon (see Figure 2 and Figure 3), discharges into the Middle Fork of the Hood River. The reservoir was constructed in 1968 for irrigation storage and has a capacity 3564 acre- feet at full pool. Since the river vio lates temperature standards, this study has been designed to construct a hydrodynamic and temperature model of Laurance reservoir in order to assess strategies for improving temperatures in the Middle Fork River. The objectives of the study are then to Develop a hydrodynamic and temperature model of Laurance Lake Calibrate the model to field data collected from November 2002 through Spring 2004 Use the model to evaluate strategies for temperature improvement through operational or structural changes to Lake Laurance The model chosen for development was CE-QUAL-W2 Version 3.2 (Cole and Wells, 2004). This is a two-dimensional unsteady hydrodynamic, temperature and water quality model that includes typical eutrophication parameters (algae, nutrients, temperature, organic matter, dissolved oxygen, pH). PSU, under the support of the Corps of Engineers Waterways Experiment Station, is a center for development of this modeling tool. Close

• 30. [Article] Pushover Analysis of Retrofitted Reinforced Concrete Buildings

  For the past decade or more, the structural engineering profession has been using the nonlinear static procedure (NSP) or pushover analysis. Modeling for such analysis requires the determination of nonlinear ...

  Citation × Citation Citation Abstract Copy Title: Pushover Analysis of Retrofitted Reinforced Concrete Buildings Author: Nahavandi, Hamidreza Year: 2015 For the past decade or more, the structural engineering profession has been using the nonlinear static procedure (NSP) or pushover analysis. Modeling for such analysis requires the determination of nonlinear properties of each component in the structure, quantified by strength and deformation capacities, which depend on the modeling assumptions. Pushover analysis is carried out for either user-defined nonlinear hinge properties or default-hinge properties, available in some programs based on the FEMA-356 such as SAP2000. While such documents provide the hinge properties for several ranges of detailing, programs may implement averaged values. In the realm of retrofitting of existing structures, few tested procedures have been identified such as steel jacketing and carbon fiber reinforced polymer (CFRP) composite jacketing system techniques in order to increase lateral stiffness of existing structures. Several methodologies have been developed using these processes in recent years. In some cases, the codes require non-linear analysis for the verification of design proposed for a retrofitting a structure. In this study, the seismic behavior of a typical residential building in South of Tehran, Iran, was investigated by performing static pushover analysis before and after retrofitting the columns. In the selected reinforced concrete (RC) structure, seismic analysis was performed for the structure retrofitted by two methods: 1) Steel jacketing and 2) CFRP jacketing technique assuming full composite action between jacketing and the existing concrete columns. By using nonlinear static (pushover) analysis, the performance level of structural members were evaluated for all structures, before and after retrofitting. The selected model building is a good representation of all typical residential buildings constructed in 1970’s in Iran. These structures are almost always without proper seismic detailing. In this study, to investigate the effectiveness of the retrofitting systems, a comparative study was performed. Title: Pushover Analysis of Retrofitted Reinforced Concrete Buildings Author: Nahavandi, Hamidreza Year: 2015 For the past decade or more, the structural engineering profession has been using the nonlinear static procedure (NSP) or pushover analysis. Modeling for such analysis requires the determination of nonlinear properties of each component in the structure, quantified by strength and deformation capacities, which depend on the modeling assumptions. Pushover analysis is carried out for either user-defined nonlinear hinge properties or default-hinge properties, available in some programs based on the FEMA-356 such as SAP2000. While such documents provide the hinge properties for several ranges of detailing, programs may implement averaged values. In the realm of retrofitting of existing structures, few tested procedures have been identified such as steel jacketing and carbon fiber reinforced polymer (CFRP) composite jacketing system techniques in order to increase lateral stiffness of existing structures. Several methodologies have been developed using these processes in recent years. In some cases, the codes require non-linear analysis for the verification of design proposed for a retrofitting a structure. In this study, the seismic behavior of a typical residential building in South of Tehran, Iran, was investigated by performing static pushover analysis before and after retrofitting the columns. In the selected reinforced concrete (RC) structure, seismic analysis was performed for the structure retrofitted by two methods: 1) Steel jacketing and 2) CFRP jacketing technique assuming full composite action between jacketing and the existing concrete columns. By using nonlinear static (pushover) analysis, the performance level of structural members were evaluated for all structures, before and after retrofitting. The selected model building is a good representation of all typical residential buildings constructed in 1970’s in Iran. These structures are almost always without proper seismic detailing. In this study, to investigate the effectiveness of the retrofitting systems, a comparative study was performed. Close

• 31. [Article] Exploring Pedestrian Responsive Traffic Signal Timing Strategies in Urban Areas

  The role of walking in the development of healthy, livable communities is being increasingly recognized. In urban areas, intersections represent locations where different modes converge, and are often ...

  Citation × Citation Citation Abstract Copy Title: Exploring Pedestrian Responsive Traffic Signal Timing Strategies in Urban Areas Author: Kothuri, Sirisha Murthy Year: 2014 The role of walking in the development of healthy, livable communities is being increasingly recognized. In urban areas, intersections represent locations where different modes converge, and are often viewed as deterrents to walking. This is due to the unwarranted and often unnecessary delays imposed by signal timing policies for pedestrians and increased potential for conflicts. Traditional signal timing design prioritizes vehicles over pedestrians leading to undesirable consequences such as large delays and risky pedestrian behaviors. Pedestrians are accommodated in a manner that is designed to cause least interruption to the flow of motor vehicles. This lack of pedestrian accommodation at signalized intersections is the focus of this dissertation. Understanding pedestrian attitudes and perceptions is important because it offers insights into actual crossing behavior at signalized intersections. An intercept survey of 367 crossing pedestrians was undertaken at four signalized intersections in Portland, Oregon, and binary logistic regression models were constructed to quantify the impacts of demographics, trip characteristics and type of infrastructure on pedestrian perceptions and attitudes regarding delay, crossing time and motivators for crossing decisions. Safety was found to have a larger effect than compliance on the decision to cross the street. Pedestrians at recall intersections expressed higher satisfaction with delay than at actuated intersections. Novel methods to measure pedestrian delay using 2070 signal controllers and Voyage software were developed. These methods have been adopted by the City of Portland to record actuation trends and delays at various intersections. In the absence of demand data, pedestrian push button actuations can be considered as a proxy for crossing demand. The micro-simulation software VISSIM was used to analyze delays resulting from varying pedestrian and vehicle volumes on a network of three intersections in Portland, Oregon. From a pedestrian perspective, free operation was found to be always beneficial due to lower pedestrian delays. However, from a system wide perspective, free operation was found to be beneficial only under low-medium traffic conditions from an overall delay reduction viewpoint, while coordinated operation showed benefits under heavy traffic conditions, irrespective of the volume of pedestrians. Control strategies were developed to identify the best mode of signal controller operation that produced the lowest overall average delay per user. A procedure to identify the optimal control strategy based on user inputs (major street volume to capacity ratios and rate of pedestrian phase serviced for the minor street) was developed. The procedure was applied to a network of three intersections in east Portland, OR and the findings were verified. This research offers significant contributions in the field of pedestrian research. The findings related to attitudes and perceptions of crossing pedestrians offer greater insights into pedestrian crossing behavior and add to the body of existing literature. The methods developed to obtain pedestrian actuations and delay data from signal controllers represent an easy and cost-effective way to characterize pedestrian service at intersections. The results pertaining to signal timing strategies represent an important step towards incorporating pedestrian needs at intersections and demonstrate how control strategies employed to benefit pedestrians could benefit the entire system. Title: Exploring Pedestrian Responsive Traffic Signal Timing Strategies in Urban Areas Author: Kothuri, Sirisha Murthy Year: 2014 The role of walking in the development of healthy, livable communities is being increasingly recognized. In urban areas, intersections represent locations where different modes converge, and are often viewed as deterrents to walking. This is due to the unwarranted and often unnecessary delays imposed by signal timing policies for pedestrians and increased potential for conflicts. Traditional signal timing design prioritizes vehicles over pedestrians leading to undesirable consequences such as large delays and risky pedestrian behaviors. Pedestrians are accommodated in a manner that is designed to cause least interruption to the flow of motor vehicles. This lack of pedestrian accommodation at signalized intersections is the focus of this dissertation. Understanding pedestrian attitudes and perceptions is important because it offers insights into actual crossing behavior at signalized intersections. An intercept survey of 367 crossing pedestrians was undertaken at four signalized intersections in Portland, Oregon, and binary logistic regression models were constructed to quantify the impacts of demographics, trip characteristics and type of infrastructure on pedestrian perceptions and attitudes regarding delay, crossing time and motivators for crossing decisions. Safety was found to have a larger effect than compliance on the decision to cross the street. Pedestrians at recall intersections expressed higher satisfaction with delay than at actuated intersections. Novel methods to measure pedestrian delay using 2070 signal controllers and Voyage software were developed. These methods have been adopted by the City of Portland to record actuation trends and delays at various intersections. In the absence of demand data, pedestrian push button actuations can be considered as a proxy for crossing demand. The micro-simulation software VISSIM was used to analyze delays resulting from varying pedestrian and vehicle volumes on a network of three intersections in Portland, Oregon. From a pedestrian perspective, free operation was found to be always beneficial due to lower pedestrian delays. However, from a system wide perspective, free operation was found to be beneficial only under low-medium traffic conditions from an overall delay reduction viewpoint, while coordinated operation showed benefits under heavy traffic conditions, irrespective of the volume of pedestrians. Control strategies were developed to identify the best mode of signal controller operation that produced the lowest overall average delay per user. A procedure to identify the optimal control strategy based on user inputs (major street volume to capacity ratios and rate of pedestrian phase serviced for the minor street) was developed. The procedure was applied to a network of three intersections in east Portland, OR and the findings were verified. This research offers significant contributions in the field of pedestrian research. The findings related to attitudes and perceptions of crossing pedestrians offer greater insights into pedestrian crossing behavior and add to the body of existing literature. The methods developed to obtain pedestrian actuations and delay data from signal controllers represent an easy and cost-effective way to characterize pedestrian service at intersections. The results pertaining to signal timing strategies represent an important step towards incorporating pedestrian needs at intersections and demonstrate how control strategies employed to benefit pedestrians could benefit the entire system. Close

• 32. [Article] Contextual Influences on Trip Generation

  There is national interest in building data that expands upon the existing Institute of Transportation Engineers (ITE) trip generation rates to include sites located in a multi-modal context. Current ITE ...

  Citation × Citation Citation Abstract Copy Title: Contextual Influences on Trip Generation Author: Clifton, Kelly J., Currans, Kristina Marie, Muhs, Christopher D. Year: 2012 There is national interest in building data that expands upon the existing Institute of Transportation Engineers (ITE) trip generation rates to include sites located in a multi-modal context. Current ITE rates represent travel behavior for development in single lots and uses, primarily measured in low-density suburban areas. Despite evidence that a more compact urban form, access to transit and a greater mix of uses generates fewer and shorter vehicle trips, local governments are often compelled to use current ITE trip generation rates to evaluate transportation impacts and calculate transportation system development charges (TSDCs). This is due to: a) the expense of collecting local data, b) lack of alternative sources of information, c) the strong industry bias toward using ITE published rates and d) the absence of a empirically tested methodology for adjusting those rates for development occurring in different land use and transportation contexts. Compounding these challenges, cities in Oregon are required to demonstrate that planning and zoning changes will not degrade the performance of state-owned transportation facilities compared to the levels of service documented in the Regional Transportation Plan under the Oregon Transportation Planning Rule, section -0060, and Oregon Highway Plan, Policy 1.F.6. These requirements can conflict with regional policies in Metro's 2040 Growth Concept that call for development of mixed-use centers and corridors to support jobs and freight reliability, a compact urban form and leverage transportation investments such as high capacity transit. Thus, there are gaps in the understanding about how best to evaluate, mitigate and plan for growth under these conditions. This research proposes to develop multi-modal trip generation rates that better reflect the relationship between land use, transportation and travel demand for specific land use types located in various urban settings. The project aims to collect local data (using multi-modal counts and establishment surveys) on a few specific land uses (deemed most problematic to estimate demand and occurring across the spectrum of urban conditions) to develop trip generation rates that are sensitive to demographic, land use and transportation contexts. These new trip rates will be compared to the ITE rates for the same land use category and a methodology for adjusting the ITE rates will be developed. This adjustment methodology will be validated, using additional data collected in this research. The research will be documented and made available to local partners and disseminated widely to reach out to other communities across the country. The research conducted for this project would account for how the built environment (e.g., both land use and transportation) influences travel behavior (number of trips, trip length, mode choice), and determine trip rates that reflect the entire activity spectrum of different development/place typologies. This is extremely important in determining the impact of different development types on the transportation system to: 1) avoid over-planning the system for the surrounding land uses; (2) suggest strategies and investment priorities to encourage more compact, mixed-use areas with more transportation choices and 3) avoid creating regulatory and/or financial barriers to compact form envisioned by local, regional and statewide plans (i.e. uniform TSDCs can result in lower impact development paying the same rates, and thus subsidizing development with higher impact costs to the transportation system). The documentation of the findings and methodology will be applicable to current and future growth and be transferable to other communities, locally and nationally, beyond the Portland region. Title: Contextual Influences on Trip Generation Author: Clifton, Kelly J., Currans, Kristina Marie, Muhs, Christopher D. Year: 2012 There is national interest in building data that expands upon the existing Institute of Transportation Engineers (ITE) trip generation rates to include sites located in a multi-modal context. Current ITE rates represent travel behavior for development in single lots and uses, primarily measured in low-density suburban areas. Despite evidence that a more compact urban form, access to transit and a greater mix of uses generates fewer and shorter vehicle trips, local governments are often compelled to use current ITE trip generation rates to evaluate transportation impacts and calculate transportation system development charges (TSDCs). This is due to: a) the expense of collecting local data, b) lack of alternative sources of information, c) the strong industry bias toward using ITE published rates and d) the absence of a empirically tested methodology for adjusting those rates for development occurring in different land use and transportation contexts. Compounding these challenges, cities in Oregon are required to demonstrate that planning and zoning changes will not degrade the performance of state-owned transportation facilities compared to the levels of service documented in the Regional Transportation Plan under the Oregon Transportation Planning Rule, section -0060, and Oregon Highway Plan, Policy 1.F.6. These requirements can conflict with regional policies in Metro's 2040 Growth Concept that call for development of mixed-use centers and corridors to support jobs and freight reliability, a compact urban form and leverage transportation investments such as high capacity transit. Thus, there are gaps in the understanding about how best to evaluate, mitigate and plan for growth under these conditions. This research proposes to develop multi-modal trip generation rates that better reflect the relationship between land use, transportation and travel demand for specific land use types located in various urban settings. The project aims to collect local data (using multi-modal counts and establishment surveys) on a few specific land uses (deemed most problematic to estimate demand and occurring across the spectrum of urban conditions) to develop trip generation rates that are sensitive to demographic, land use and transportation contexts. These new trip rates will be compared to the ITE rates for the same land use category and a methodology for adjusting the ITE rates will be developed. This adjustment methodology will be validated, using additional data collected in this research. The research will be documented and made available to local partners and disseminated widely to reach out to other communities across the country. The research conducted for this project would account for how the built environment (e.g., both land use and transportation) influences travel behavior (number of trips, trip length, mode choice), and determine trip rates that reflect the entire activity spectrum of different development/place typologies. This is extremely important in determining the impact of different development types on the transportation system to: 1) avoid over-planning the system for the surrounding land uses; (2) suggest strategies and investment priorities to encourage more compact, mixed-use areas with more transportation choices and 3) avoid creating regulatory and/or financial barriers to compact form envisioned by local, regional and statewide plans (i.e. uniform TSDCs can result in lower impact development paying the same rates, and thus subsidizing development with higher impact costs to the transportation system). The documentation of the findings and methodology will be applicable to current and future growth and be transferable to other communities, locally and nationally, beyond the Portland region. Close