Structural reliability theories are used in the calibration of load and resistance factor design (LRFD) in the Canadian Highway Bridge Design Code (CHBDC). The LRFD approach contains certain assumptions about uncertainties in the load and capacity estimation that prevent it from fully exploiting the information gathered during visual inspections. This paper presents a reliability-based framework for analyzing the visual inspection data obtained according to the Ontario structure inspection manual (OSIM). Existing deterioration models are adapted. The Bayesian interference is utilized to estimate the updated structural properties according to the prior information from the bridge maintenance and deterioration models and the new information collected from visual inspections. The criteria set by the CHBDC are used to analyze components and systems reliability. The value of the proposed framework for bridge evaluation and optimizing maintenance is demonstrated through the full implementation of a case-study bridge in the Canadian Province of NB.
{"title":"Structural reliability assessment of steel bridges using OSIM visual inspection data and Bayesian updating","authors":"Mohamad Salaheddine, Kaveh Arjomandi","doi":"10.1139/cjce-2022-0134","DOIUrl":"https://doi.org/10.1139/cjce-2022-0134","url":null,"abstract":"Structural reliability theories are used in the calibration of load and resistance factor design (LRFD) in the Canadian Highway Bridge Design Code (CHBDC). The LRFD approach contains certain assumptions about uncertainties in the load and capacity estimation that prevent it from fully exploiting the information gathered during visual inspections. This paper presents a reliability-based framework for analyzing the visual inspection data obtained according to the Ontario structure inspection manual (OSIM). Existing deterioration models are adapted. The Bayesian interference is utilized to estimate the updated structural properties according to the prior information from the bridge maintenance and deterioration models and the new information collected from visual inspections. The criteria set by the CHBDC are used to analyze components and systems reliability. The value of the proposed framework for bridge evaluation and optimizing maintenance is demonstrated through the full implementation of a case-study bridge in the Canadian Province of NB.","PeriodicalId":9414,"journal":{"name":"Canadian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135406668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Baisali Dutta, Amar Nath Nayak, S. Dirar, Bharadwaj Nanda, M. Theofanous
The shear performances of simply supported (SS) and continuous (CN) reinforced concrete T-beams strengthened with deep embedded (DE) steel or carbon fibre reinforced polymer bars are compared in this investigation. A nonlinear finite element (NLFE) analysis is performed for this purpose by modelling these beams with the FEM software by validating with the experimental data from the published papers. The experimental and NLFE shear strength values are then compared with those of the available design models to examine the efficacy of these models. Thereafter, the parametric study is conducted to obtain the impact of beam types (SS and CN) on the structural performances. It shows that the DE strengthened CN beam provides higher shear capacity in comparison to the corresponding SS beam. However, the enhancements of the shear strength of SS beam due to strengthening with DE bars are significantly higher than that of the corresponding CN one.
本研究比较了使用深埋（DE）钢筋或碳纤维增强聚合物钢筋加固的简支撑（SS）和连续（CN）加固混凝土 T 型梁的抗剪性能。为此，使用有限元软件对这些梁进行了建模，并与已发表论文中的实验数据进行了验证，从而进行了非线性有限元（NLFE）分析。然后将实验值和 NLFE 剪力强度值与现有设计模型进行比较，以检验这些模型的有效性。随后，进行了参数研究，以了解梁类型（SS 和 CN）对结构性能的影响。结果表明，与相应的 SS 梁相比，DE 增强 CN 梁具有更高的抗剪能力。然而，使用 DE 杆件加固后，SS 梁的抗剪强度明显高于相应的 CN 梁。
{"title":"Nonlinear finite element investigation on shear behaviour of simply supported and continuous RC T-beams retrofitted with deep embedded CFRP/steel bars","authors":"Baisali Dutta, Amar Nath Nayak, S. Dirar, Bharadwaj Nanda, M. Theofanous","doi":"10.1139/cjce-2022-0267","DOIUrl":"https://doi.org/10.1139/cjce-2022-0267","url":null,"abstract":"The shear performances of simply supported (SS) and continuous (CN) reinforced concrete T-beams strengthened with deep embedded (DE) steel or carbon fibre reinforced polymer bars are compared in this investigation. A nonlinear finite element (NLFE) analysis is performed for this purpose by modelling these beams with the FEM software by validating with the experimental data from the published papers. The experimental and NLFE shear strength values are then compared with those of the available design models to examine the efficacy of these models. Thereafter, the parametric study is conducted to obtain the impact of beam types (SS and CN) on the structural performances. It shows that the DE strengthened CN beam provides higher shear capacity in comparison to the corresponding SS beam. However, the enhancements of the shear strength of SS beam due to strengthening with DE bars are significantly higher than that of the corresponding CN one.","PeriodicalId":9414,"journal":{"name":"Canadian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139334922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the differences in the factors affecting the injury severity of speeding-related crashes occurring in the daytime and nighttime. Two log-likelihood ratio tests are conducted to validate whether speeding-related crashes classified by daytime and nighttime should be modeled separately. The result proves that separate modeling is necessary. Two correlated random parameter order probit models with heterogeneity in means are conducted using the data collected from 2018 to 2020 in the United States. Model estimation results show that urban areas, speed limits, and young and older drivers are temporal instability. Angle crashes, head-on crashes, intersections, downhill, exceeding the speed limit, drunk driving, and motorcycles are statistically significant in both models with an increased crash severity. Interaction and heterogeneity effects between random parameters are also reported. For instance, large trucks driving above the speed limit are more likely to increase the probability of severe injury.
{"title":"Investigating the difference in factors influencing the injury severity between daytime and nighttime speeding-related crashes","authors":"renteng yuan, Qiaojun Xiang, Yan Huang, Xin Gu","doi":"10.1139/cjce-2023-0043","DOIUrl":"https://doi.org/10.1139/cjce-2023-0043","url":null,"abstract":"This study investigates the differences in the factors affecting the injury severity of speeding-related crashes occurring in the daytime and nighttime. Two log-likelihood ratio tests are conducted to validate whether speeding-related crashes classified by daytime and nighttime should be modeled separately. The result proves that separate modeling is necessary. Two correlated random parameter order probit models with heterogeneity in means are conducted using the data collected from 2018 to 2020 in the United States. Model estimation results show that urban areas, speed limits, and young and older drivers are temporal instability. Angle crashes, head-on crashes, intersections, downhill, exceeding the speed limit, drunk driving, and motorcycles are statistically significant in both models with an increased crash severity. Interaction and heterogeneity effects between random parameters are also reported. For instance, large trucks driving above the speed limit are more likely to increase the probability of severe injury.","PeriodicalId":9414,"journal":{"name":"Canadian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135385679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Most car-following models have mainly focused on the effects of the lead vehicle on the target vehicle's behaviour or the driver's forward-looking effects, but not the effects of the vehicle behind the target vehicle (the following vehicle) or the driver's backward-looking effects. Therefore, this study proposes a data-driven car-following model that incorporates both backward- and forward-looking effects using a deep neural network (DNN). This model is called the “DNN with backward-looking effect (DNN-BE) model”. The DNN-BE model produced higher prediction accuracy than the DNN model with forward-looking effects only and a conventional mathematical car-following model that considers both forward- and backward-looking effects. It was found that the target vehicle is more likely to accelerate when the spacing with the following vehicle is shorter and the spacing with the lead vehicle is longer. The result of permutation importance also shows that variables related to the following vehicle are more important when the spacing with the following vehicles is shorter.
{"title":"An Extended Car-Following Model Considering Backward-Looking Effect: A Machine Learning Approach","authors":"Ayobami Adewale, Chris Lee","doi":"10.1139/cjce-2023-0018","DOIUrl":"https://doi.org/10.1139/cjce-2023-0018","url":null,"abstract":"Most car-following models have mainly focused on the effects of the lead vehicle on the target vehicle's behaviour or the driver's forward-looking effects, but not the effects of the vehicle behind the target vehicle (the following vehicle) or the driver's backward-looking effects. Therefore, this study proposes a data-driven car-following model that incorporates both backward- and forward-looking effects using a deep neural network (DNN). This model is called the “DNN with backward-looking effect (DNN-BE) model”. The DNN-BE model produced higher prediction accuracy than the DNN model with forward-looking effects only and a conventional mathematical car-following model that considers both forward- and backward-looking effects. It was found that the target vehicle is more likely to accelerate when the spacing with the following vehicle is shorter and the spacing with the lead vehicle is longer. The result of permutation importance also shows that variables related to the following vehicle are more important when the spacing with the following vehicles is shorter.","PeriodicalId":9414,"journal":{"name":"Canadian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135534490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A large amount of research has been undertaken on tubular bolted end-plate connections loaded in axial tension, and considerably less on such connections in flexure. This paper studies the combined effects of these two loads and presents the first laboratory tests on these connections under combined tension and flexure. Using validated finite element models, a parametric study with 360 numerical models is performed on these connections under axial and eccentric tension loads. After screening this database of experimental tests and numerical results to isolate only connection failure modes, current design methods for predicting the connection capacity under eccentric tension are evaluated and revised. In addition, based on interaction curves, a novel approach is proposed to design these splices under combined loads. For all methods, the use of the plate ultimate and yield stress was compared for the end-plate material strength parameter. Lastly, a reliability analysis is performed for the application of the recommended design methods to Canadian practice.
{"title":"Bolted End-Plate Tube Connections subject to Tension and Bending","authors":"Augusto Fidalgo, Jeffrey A. Packer","doi":"10.1139/cjce-2023-0207","DOIUrl":"https://doi.org/10.1139/cjce-2023-0207","url":null,"abstract":"A large amount of research has been undertaken on tubular bolted end-plate connections loaded in axial tension, and considerably less on such connections in flexure. This paper studies the combined effects of these two loads and presents the first laboratory tests on these connections under combined tension and flexure. Using validated finite element models, a parametric study with 360 numerical models is performed on these connections under axial and eccentric tension loads. After screening this database of experimental tests and numerical results to isolate only connection failure modes, current design methods for predicting the connection capacity under eccentric tension are evaluated and revised. In addition, based on interaction curves, a novel approach is proposed to design these splices under combined loads. For all methods, the use of the plate ultimate and yield stress was compared for the end-plate material strength parameter. Lastly, a reliability analysis is performed for the application of the recommended design methods to Canadian practice.","PeriodicalId":9414,"journal":{"name":"Canadian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135535171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abimbola Grace Oyeyi, Hanaa Khaleel Alwan Al-Bayati, Frank Mi-Way Ni, Susan Tighe
Previous analytical studies have demonstrated that low-density lightweight cellular concrete (LCC) subbase pavements can support up to 20 times more traffic loads than unbound granular subbase pavements while protecting the pavement subgrade from adverse freeze–thaw effects in cold regions. This study examines the possibility of providing better-performing pavements on the field through the construction, instrumentation, and monitoring of flexible pavement sections incorporating three LCC densities (400, 475, and 600 kg/m³) as subbase material compared with unbound granular material in Canada. The effects of daily and seasonal temperatures on pavement critical responses to stress and strains were evaluated. The findings showed that these LCC pavements reduced asphalt concrete tensile strain by over two times compared with unbound granular pavements, and that strain increased with a daily temperature increase. Daily subgrade pressure (stress) change was reduced by up to 68%. The study concluded that longer life pavements could be achieved with LCC subbase thicknesses ≥250 mm.
{"title":"Environmental Impact on Critical Responses of Lightweight Cellular Concrete Subbase Flexible Pavements","authors":"Abimbola Grace Oyeyi, Hanaa Khaleel Alwan Al-Bayati, Frank Mi-Way Ni, Susan Tighe","doi":"10.1139/cjce-2023-0027","DOIUrl":"https://doi.org/10.1139/cjce-2023-0027","url":null,"abstract":"Previous analytical studies have demonstrated that low-density lightweight cellular concrete (LCC) subbase pavements can support up to 20 times more traffic loads than unbound granular subbase pavements while protecting the pavement subgrade from adverse freeze–thaw effects in cold regions. This study examines the possibility of providing better-performing pavements on the field through the construction, instrumentation, and monitoring of flexible pavement sections incorporating three LCC densities (400, 475, and 600 kg/m³) as subbase material compared with unbound granular material in Canada. The effects of daily and seasonal temperatures on pavement critical responses to stress and strains were evaluated. The findings showed that these LCC pavements reduced asphalt concrete tensile strain by over two times compared with unbound granular pavements, and that strain increased with a daily temperature increase. Daily subgrade pressure (stress) change was reduced by up to 68%. The study concluded that longer life pavements could be achieved with LCC subbase thicknesses ≥250 mm.","PeriodicalId":9414,"journal":{"name":"Canadian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135814294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, the effect of ternary binder containing Portland cement type I (PCI), slag, and limestone (LS) powder in varying proportions on the suction development and the mechanical strength of cemented paste backfill (CPB) was investigated. Mechanical tests, microstructural analyses (thermo-gravimetry analysis (TG/DTG) and mercury intrusion porosimetry), and monitoring (suction, electrical conductivity, and temperature) experiments were conducted on CPB. In the first part of this study, binary binders with two different PCI:slag proportions, 50:50 and 80:20, were examined with no LS, followed by the slag replacement with increasing weight percentages of LS from 0% to 20% by weight of the total binder, with constant cement content. The results indicate that the slow slag hydration kinetics decreased the suction and strength gain rate at a young age in the binary sample with high slag content (50 wt.%); however, its latent hydraulic and pozzolanic properties enhanced the strength gain at a later age, from 28 days. The addition of 5 wt.% and 10 wt.% LS to the ternary binder system improved the early age strength of CPB up to 7 days and 1 day, respectively, compared with the binary control samples, i.e., CPB with slag and without LS. While the addition of up to 10% LS to the ternary binder improved the rate of suction development and increased suction at early ages, beyond 10%, the addition of LS slightly decreased mechanical performance at all ages. Overall, the results obtained reveal that up to 50 wt.% slag with up to 10 wt.% LS with cement could be used as a ternary binder to improve the early age strength and suction development rate of CPB studied without significant loss in compressive strength at advanced ages. The results of this research could be of great benefit to the mining industry through the use of a ternary binder to replace cement, which could improve the overall performance of the CPB system, facilitate a more sustainable CPB design, and improve tailings management practices and overall economics.
{"title":"Strength and suction development of cemented paste backfill with ternary cement blends","authors":"Aparna Sagade, Mamadou Fall, Zubaida Al-moselly","doi":"10.1139/cjce-2023-0020","DOIUrl":"https://doi.org/10.1139/cjce-2023-0020","url":null,"abstract":"In this paper, the effect of ternary binder containing Portland cement type I (PCI), slag, and limestone (LS) powder in varying proportions on the suction development and the mechanical strength of cemented paste backfill (CPB) was investigated. Mechanical tests, microstructural analyses (thermo-gravimetry analysis (TG/DTG) and mercury intrusion porosimetry), and monitoring (suction, electrical conductivity, and temperature) experiments were conducted on CPB. In the first part of this study, binary binders with two different PCI:slag proportions, 50:50 and 80:20, were examined with no LS, followed by the slag replacement with increasing weight percentages of LS from 0% to 20% by weight of the total binder, with constant cement content. The results indicate that the slow slag hydration kinetics decreased the suction and strength gain rate at a young age in the binary sample with high slag content (50 wt.%); however, its latent hydraulic and pozzolanic properties enhanced the strength gain at a later age, from 28 days. The addition of 5 wt.% and 10 wt.% LS to the ternary binder system improved the early age strength of CPB up to 7 days and 1 day, respectively, compared with the binary control samples, i.e., CPB with slag and without LS. While the addition of up to 10% LS to the ternary binder improved the rate of suction development and increased suction at early ages, beyond 10%, the addition of LS slightly decreased mechanical performance at all ages. Overall, the results obtained reveal that up to 50 wt.% slag with up to 10 wt.% LS with cement could be used as a ternary binder to improve the early age strength and suction development rate of CPB studied without significant loss in compressive strength at advanced ages. The results of this research could be of great benefit to the mining industry through the use of a ternary binder to replace cement, which could improve the overall performance of the CPB system, facilitate a more sustainable CPB design, and improve tailings management practices and overall economics.","PeriodicalId":9414,"journal":{"name":"Canadian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136263523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PHANI KUMAR PATNALA, Jonathan D Regehr, Babak Mehran, Chaouki Regoui
Resilience is a multidisciplinary concept that deals with rapid response and recovery of a system experiencing a disruption. Despite extensive research on this topic, there is a need to clarify resilience concepts in the context of road freight transportation systems (FTSs) from a three-dimensional perspective (i.e., physical infrastructure, users, and managing organizations) and to identify persistent knowledge gaps concerning the characterization and measurement of FTS resilience vis-à-vis disruptive events. This paper addresses these shortcomings through a systematic review of 149 research studies. The synthesis of findings clarifies inconsistencies associated with the characteristics of FTS resilience and in so doing, establishes a unified framework for measuring FTS resilience through the life cycle of disruptive events. Critical data gaps, methodological shortcomings, and a lack of empirical evidence concerning FTS resilience to disruptive events remain. More robust analytical approaches are required to incorporate interdependencies among FTS dimensions into resilience assessments.
{"title":"Resilience for Freight Transportation Systems to Disruptive Events: A Review of Concepts and Metrics","authors":"PHANI KUMAR PATNALA, Jonathan D Regehr, Babak Mehran, Chaouki Regoui","doi":"10.1139/cjce-2023-0187","DOIUrl":"https://doi.org/10.1139/cjce-2023-0187","url":null,"abstract":"Resilience is a multidisciplinary concept that deals with rapid response and recovery of a system experiencing a disruption. Despite extensive research on this topic, there is a need to clarify resilience concepts in the context of road freight transportation systems (FTSs) from a three-dimensional perspective (i.e., physical infrastructure, users, and managing organizations) and to identify persistent knowledge gaps concerning the characterization and measurement of FTS resilience vis-à-vis disruptive events. This paper addresses these shortcomings through a systematic review of 149 research studies. The synthesis of findings clarifies inconsistencies associated with the characteristics of FTS resilience and in so doing, establishes a unified framework for measuring FTS resilience through the life cycle of disruptive events. Critical data gaps, methodological shortcomings, and a lack of empirical evidence concerning FTS resilience to disruptive events remain. More robust analytical approaches are required to incorporate interdependencies among FTS dimensions into resilience assessments.","PeriodicalId":9414,"journal":{"name":"Canadian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135059623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Short-span bridges are one of the most frequent infrastructures along railway tracks where railway track stiffness suddenly changes. The sudden variation in the vertical stiffness of railway tracks increases dynamic loads and causes numerous defects in ballasted railroads. Therefore, improving the dynamic performance of railway tracks can be conducted by constructing countermeasures along the transition zone. In this regard, the approach slab is a practical technique used in railway-bridge transition zones. As the dimensional shape of the approach slab plays a significant role in the dynamic response of transition zones, this study evaluated the effects of its main geometric parameters. A three-dimensional model of the railway portal bridge, including the approach slab, was built using the finite element method and analyzed by imposing moving wheel loads as a series of acting force points along rail elements. The model was validated with field-obtained results acquired through a laser/camera-based measuring technique. Then, some sensitivity analyses were performed to find optimized geometric dimensions of approach slabs to improve the dynamic behavior of railway-bridge transition zones. Obtained results of the geometrical sensitivity analysis show that when the geometrically optimized approach slab is used along the railway-bridge transition zone, the displacements of rail and ballast are decreased by 24% and 18%, respectively.
{"title":"Evaluating the Dynamic Behavior of Railway-Bridge Transition Zone; Numerical and Field Measurements","authors":"Hamidreza Heydari","doi":"10.1139/cjce-2022-0453","DOIUrl":"https://doi.org/10.1139/cjce-2022-0453","url":null,"abstract":"Short-span bridges are one of the most frequent infrastructures along railway tracks where railway track stiffness suddenly changes. The sudden variation in the vertical stiffness of railway tracks increases dynamic loads and causes numerous defects in ballasted railroads. Therefore, improving the dynamic performance of railway tracks can be conducted by constructing countermeasures along the transition zone. In this regard, the approach slab is a practical technique used in railway-bridge transition zones. As the dimensional shape of the approach slab plays a significant role in the dynamic response of transition zones, this study evaluated the effects of its main geometric parameters. A three-dimensional model of the railway portal bridge, including the approach slab, was built using the finite element method and analyzed by imposing moving wheel loads as a series of acting force points along rail elements. The model was validated with field-obtained results acquired through a laser/camera-based measuring technique. Then, some sensitivity analyses were performed to find optimized geometric dimensions of approach slabs to improve the dynamic behavior of railway-bridge transition zones. Obtained results of the geometrical sensitivity analysis show that when the geometrically optimized approach slab is used along the railway-bridge transition zone, the displacements of rail and ballast are decreased by 24% and 18%, respectively.","PeriodicalId":9414,"journal":{"name":"Canadian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135059619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bioretention cells in the Toronto region are usually sized to accommodate runoff from the 90th percentile storm, which has a depth of about 25 mm. This research examines the water quality control performance and cost of bioretention cells sized to satisfy alternative design criteria ranging from 5 to 50 mm. The long-term average runoff-capture efficiencies provided by representative bioretention cells are determined, and their capital as well as operation and maintenance costs are estimated. Results indicate that the current design criterion of 25 mm is probably too high and not cost-efficient. In fact, above some threshold levels, little improvement in runoff-capture and pollutant removal performances may be achieved if the design criterion is increased further, but cost would still linearly increase. Presented here is a methodology that can be used to properly consider both the performance and cost of bioretention cells for establishing a more cost-efficient design criterion. It is shown that a more cost-efficient design criterion for Toronto could be lower than the current one, and significant cost savings can be realized if a lower design criterion is implemented. Some inappropriate ways of quantifying the effective volume of storage provided by bioretention cells are also identified in this paper.
{"title":"A Closer Look at Toronto’s Water Quality Control Design Criteria for Bioretention Cells","authors":"Elizabeth Rowe, Yiping Guo, Zhong Li","doi":"10.1139/cjce-2023-0148","DOIUrl":"https://doi.org/10.1139/cjce-2023-0148","url":null,"abstract":"Bioretention cells in the Toronto region are usually sized to accommodate runoff from the 90th percentile storm, which has a depth of about 25 mm. This research examines the water quality control performance and cost of bioretention cells sized to satisfy alternative design criteria ranging from 5 to 50 mm. The long-term average runoff-capture efficiencies provided by representative bioretention cells are determined, and their capital as well as operation and maintenance costs are estimated. Results indicate that the current design criterion of 25 mm is probably too high and not cost-efficient. In fact, above some threshold levels, little improvement in runoff-capture and pollutant removal performances may be achieved if the design criterion is increased further, but cost would still linearly increase. Presented here is a methodology that can be used to properly consider both the performance and cost of bioretention cells for establishing a more cost-efficient design criterion. It is shown that a more cost-efficient design criterion for Toronto could be lower than the current one, and significant cost savings can be realized if a lower design criterion is implemented. Some inappropriate ways of quantifying the effective volume of storage provided by bioretention cells are also identified in this paper.","PeriodicalId":9414,"journal":{"name":"Canadian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135059622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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