Wind stability and design loads of long-span bridges are assessed applying experimental and theoretical methods. The commonly used approach entails the extraction of fundamental aerodynamic data of key structural elements such as the deck, towers, and cables, either experimentally or numerically, and the application of theoretical models for evaluation of structural responses to turbulent winds. This phenomenon called buffeting is extremely complex and, to date, there is no closed-form theoretical model to reproduce how the wind converts to structural responses and loads which the bridge must resist. The objective of this paper is to explore the base of the problem, namely the transformation of wind gusts to actual loads, and the response estimations. The time domain response approach has been adopted for solution of the generalized equations of motion allowing the exploration of details in the performance of various theoretical interpretations. Starting from the classic quasi-static linear model, theoretical simplifications are removed toward a more complete model of buffeting loads. Non-linear and aerodynamic coupling effects on response predictions are examined specifically aiming at improved buffeting load representations within the framework of the currently available experimental data. A new concept called stack state-space analysis has been introduced for the response solution to wind buffeting. Aerodynamic and structural data of Pierre-Laporte Bridge in Québec City, and the IABSE Working Group 10, long-span bridge validation example, are utilized as representative cases in this study. Avenues for further experimental and numerical validations of the presented new solution approach are suggested toward more accurate predictions of wind response and design loads of long-span bridges.
{"title":"Buffeting response analysis – the stack state-space approach","authors":"S. Stoyanoff, Z. Taylor, P. Dallaire, G. Larose","doi":"10.3233/brs-230210","DOIUrl":"https://doi.org/10.3233/brs-230210","url":null,"abstract":"Wind stability and design loads of long-span bridges are assessed applying experimental and theoretical methods. The commonly used approach entails the extraction of fundamental aerodynamic data of key structural elements such as the deck, towers, and cables, either experimentally or numerically, and the application of theoretical models for evaluation of structural responses to turbulent winds. This phenomenon called buffeting is extremely complex and, to date, there is no closed-form theoretical model to reproduce how the wind converts to structural responses and loads which the bridge must resist. The objective of this paper is to explore the base of the problem, namely the transformation of wind gusts to actual loads, and the response estimations. The time domain response approach has been adopted for solution of the generalized equations of motion allowing the exploration of details in the performance of various theoretical interpretations. Starting from the classic quasi-static linear model, theoretical simplifications are removed toward a more complete model of buffeting loads. Non-linear and aerodynamic coupling effects on response predictions are examined specifically aiming at improved buffeting load representations within the framework of the currently available experimental data. A new concept called stack state-space analysis has been introduced for the response solution to wind buffeting. Aerodynamic and structural data of Pierre-Laporte Bridge in Québec City, and the IABSE Working Group 10, long-span bridge validation example, are utilized as representative cases in this study. Avenues for further experimental and numerical validations of the presented new solution approach are suggested toward more accurate predictions of wind response and design loads of long-span bridges.","PeriodicalId":43279,"journal":{"name":"Bridge Structures","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42676283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiao-Ni Gao, Hong-Wei Ren, Ruizhao Liu, Min Chen, Rui-Xin Lai
How to quickly and accurately identify the bridge rubber bearing deterioration plays an important role in ensuring the bridge structure and road safety. This paper selects the common rubber bearings of domestic bridges as the research object, and proposes an improved YOLOv4-based bridge rubber bearing deterioration detection algorithm to address the reasons for the difficulty in detecting bridge rubber bearing deterioration due to large scale variations and small sample data sets. An image dataset (named HRBD) with annotations is constructed from real inspection scenarios, and the data is expanded by image processing means such as rotation, translation and brightness transformation, so that this dataset has sufficient data complexity and solves the problem of overfitting due to insufficient samples for network training. The anchor applicable to this dataset was regained by the K-means++ clustering algorithm, and then the CA module was inserted into the YOLOv4 backbone network for more accurate anchor localization. The improved YOLOv4 network was used for migration learning to train the dataset, and finally the trained network model was used for detection on the test set. The experimental results show that the improved YOLOv4 bridge rubber bearing deterioration detection and identification network can effectively identify and locate bridge rubber bearings and their deterioration types (crack damage, shear deformation, bearing void).
{"title":"Study on deterioration identification method of rubber bearings for bridges based on YOLOv4 deep learning algorithm","authors":"Xiao-Ni Gao, Hong-Wei Ren, Ruizhao Liu, Min Chen, Rui-Xin Lai","doi":"10.3233/brs-230209","DOIUrl":"https://doi.org/10.3233/brs-230209","url":null,"abstract":"How to quickly and accurately identify the bridge rubber bearing deterioration plays an important role in ensuring the bridge structure and road safety. This paper selects the common rubber bearings of domestic bridges as the research object, and proposes an improved YOLOv4-based bridge rubber bearing deterioration detection algorithm to address the reasons for the difficulty in detecting bridge rubber bearing deterioration due to large scale variations and small sample data sets. An image dataset (named HRBD) with annotations is constructed from real inspection scenarios, and the data is expanded by image processing means such as rotation, translation and brightness transformation, so that this dataset has sufficient data complexity and solves the problem of overfitting due to insufficient samples for network training. The anchor applicable to this dataset was regained by the K-means++ clustering algorithm, and then the CA module was inserted into the YOLOv4 backbone network for more accurate anchor localization. The improved YOLOv4 network was used for migration learning to train the dataset, and finally the trained network model was used for detection on the test set. The experimental results show that the improved YOLOv4 bridge rubber bearing deterioration detection and identification network can effectively identify and locate bridge rubber bearings and their deterioration types (crack damage, shear deformation, bearing void).","PeriodicalId":43279,"journal":{"name":"Bridge Structures","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46353955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jie Li, H. Cui, Ziwei Ma, Haikuan Liu, Yuanhong Hu
Impact factor is amplification factor of vertical dynamic effect produced by vehicles. It is a main parameter of bridge design and an important index of dynamic load effect evaluation. In order to study the influence of structure and excitation factors on the impact factor of highway bridges, and then obtain the real impact factor of the continuous beam arch composite bridge, taking a three-span arch bridge made with continuous composite concrete filled steel tube beams as an example, considering the vehicle-bridge coupling vibration effect, the spatial beam element model of the bridge and the half vehicle model with the three-axis are established by using ANSYS. The impact factor of different parts of the main beam and different responses affected by the deck surface roughness, the vehicle speed and the number of vehicles are analyzed. The binary regression formula of impact factor is obtained by taking the vehicle speed and the roughness of bridge deck as independent variables. Finally, the formula is verified by the measured data of two bridges with similar fundamental frequencies. The results show that the impact factor calculated by the current code is generally small for the bridge structure with complex structure and relatively low frequency, such as arch bridge made with continuous composite concrete filled steel tube beams. The impact factor is most affected by the roughness of bridge deck. When the roughness of bridge deck reaches grade B or above, the impact factor exceeds the specification value, and the maximum impact factor can reach 5.42 times of the specification value. For the main beam, the impact factors of different external excitation, different responses and different parts are not the same, and some impact factors exceed the specification value. The regression formula of impact factor given can be used to estimate the impact factor of main beams of similar structures.
{"title":"Study of impact factor of arch bridge made with continuous composite concrete filled steel tube beams","authors":"Jie Li, H. Cui, Ziwei Ma, Haikuan Liu, Yuanhong Hu","doi":"10.3233/brs-220200","DOIUrl":"https://doi.org/10.3233/brs-220200","url":null,"abstract":"Impact factor is amplification factor of vertical dynamic effect produced by vehicles. It is a main parameter of bridge design and an important index of dynamic load effect evaluation. In order to study the influence of structure and excitation factors on the impact factor of highway bridges, and then obtain the real impact factor of the continuous beam arch composite bridge, taking a three-span arch bridge made with continuous composite concrete filled steel tube beams as an example, considering the vehicle-bridge coupling vibration effect, the spatial beam element model of the bridge and the half vehicle model with the three-axis are established by using ANSYS. The impact factor of different parts of the main beam and different responses affected by the deck surface roughness, the vehicle speed and the number of vehicles are analyzed. The binary regression formula of impact factor is obtained by taking the vehicle speed and the roughness of bridge deck as independent variables. Finally, the formula is verified by the measured data of two bridges with similar fundamental frequencies. The results show that the impact factor calculated by the current code is generally small for the bridge structure with complex structure and relatively low frequency, such as arch bridge made with continuous composite concrete filled steel tube beams. The impact factor is most affected by the roughness of bridge deck. When the roughness of bridge deck reaches grade B or above, the impact factor exceeds the specification value, and the maximum impact factor can reach 5.42 times of the specification value. For the main beam, the impact factors of different external excitation, different responses and different parts are not the same, and some impact factors exceed the specification value. The regression formula of impact factor given can be used to estimate the impact factor of main beams of similar structures.","PeriodicalId":43279,"journal":{"name":"Bridge Structures","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43128486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Barth, G. Michaelson, Robert M. Tennant, Brook Woldegabriel
The scope of this effort is to evaluate the performance of a link slab transversely connecting press-brake-formed tub girders (PBFTG). Modular PBFTGs were developed by a technical working group within the Steel Market Development Institute’s (a business unit of the American Iron and Steel Institute) Short Span Steel Bridge Alliance, led by the current authors. This working group consists of stakeholders in the steel bridge industry, including mills, fabricators, service centers, industry trade organizations, universities, and bridge owners. A full-scale link slab transversely joining two PBFTGs was fatigue loaded simulating a 75-year fatigue life in a rural environment. Strain and deflection data was recorded and compared throughout the fatigue life to determine the link slab’s effectiveness. Results of this effort show the link slab detail performs adequately throughout its fatigue life.
{"title":"Experimental assessment of link slabs in continuous span applications of press-brake-formed tub girders","authors":"K. Barth, G. Michaelson, Robert M. Tennant, Brook Woldegabriel","doi":"10.3233/brs-220201","DOIUrl":"https://doi.org/10.3233/brs-220201","url":null,"abstract":"The scope of this effort is to evaluate the performance of a link slab transversely connecting press-brake-formed tub girders (PBFTG). Modular PBFTGs were developed by a technical working group within the Steel Market Development Institute’s (a business unit of the American Iron and Steel Institute) Short Span Steel Bridge Alliance, led by the current authors. This working group consists of stakeholders in the steel bridge industry, including mills, fabricators, service centers, industry trade organizations, universities, and bridge owners. A full-scale link slab transversely joining two PBFTGs was fatigue loaded simulating a 75-year fatigue life in a rural environment. Strain and deflection data was recorded and compared throughout the fatigue life to determine the link slab’s effectiveness. Results of this effort show the link slab detail performs adequately throughout its fatigue life.","PeriodicalId":43279,"journal":{"name":"Bridge Structures","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43932029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seismic retrofit is a cost-effective and sustainable solution for improving bridge structures in seismic zones. Fiber Reinforced Polymer (FRP) is commonly used to replace steel components in retrofit projects due to their light weight, high strength, and high corrosion resistance. The fabrication of novel hybrid structures from FRP and concrete is the next step researchers are addressing. In this context, the present study focuses on numerical modeling of the experimentally determined response of a hybrid FRP and concrete bridge pier subjected to quasi-static tests. The results from FEM showed strong agreement with the experimental response in terms of load-displacement curve and failure mode. After validating the model, alternative designs (changing the height of the CFRP slab, changing the height and compaction of the CFRP bar, and concrete encasement with and without CFRP slab) were numerically tested to investigate the effects of each model on the load capacity. With the conventional concrete encasement, the bearing capacity of the bridge pier can be rehabilitated, but with the CFRP plate in the above system, the bearing capacity of the bridge pier is increased by more than 60%. Therefore, it can be concluded that seismic strengthening techniques with CFRP sheets and mounted NSM-CFRP bars are suitable for concrete bridge piers.
{"title":"Evaluation of hybrid NSM-CFRP technical bars and FRP sheets for seismic rehabilitation of a concrete bridge pier","authors":"Mohamad R. Shokrzadeh, F. Nateghi-Alahi","doi":"10.3233/brs-290180","DOIUrl":"https://doi.org/10.3233/brs-290180","url":null,"abstract":"Seismic retrofit is a cost-effective and sustainable solution for improving bridge structures in seismic zones. Fiber Reinforced Polymer (FRP) is commonly used to replace steel components in retrofit projects due to their light weight, high strength, and high corrosion resistance. The fabrication of novel hybrid structures from FRP and concrete is the next step researchers are addressing. In this context, the present study focuses on numerical modeling of the experimentally determined response of a hybrid FRP and concrete bridge pier subjected to quasi-static tests. The results from FEM showed strong agreement with the experimental response in terms of load-displacement curve and failure mode. After validating the model, alternative designs (changing the height of the CFRP slab, changing the height and compaction of the CFRP bar, and concrete encasement with and without CFRP slab) were numerically tested to investigate the effects of each model on the load capacity. With the conventional concrete encasement, the bearing capacity of the bridge pier can be rehabilitated, but with the CFRP plate in the above system, the bearing capacity of the bridge pier is increased by more than 60%. Therefore, it can be concluded that seismic strengthening techniques with CFRP sheets and mounted NSM-CFRP bars are suitable for concrete bridge piers.","PeriodicalId":43279,"journal":{"name":"Bridge Structures","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48939721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the effect of superstructure configuration on the optimum design of slab on Precast I (PCI) girder bridges. For this purpose, more than 20,000 bridge cases of varying superstructure configurations are considered to investigate the effects of various superstructure parameters such as girder spacing, span length, slab thickness and girder types on the optimum design of slab on PCI girder bridges. PCI girders are designed conforming to the AASHTO LRFD for flexure using stress limits at the service limit state, then checked at ultimate for flexure and shear using factored loads at the strength limit state. A modified harmony search optimization algorithm is used to obtain optimum bridge design parameters using standard AASHTO PCI girders according to these AASHTO LRFD requirements. Those girders are designed taking into consideration geometrical constraints, stress constraints and constraints related to the conformity of the design with the AASHTO LRFD code. Various sensitivity analysis are performed to investigate the effect of different geometrical factors on the design of the girders, and easy-to-use design aids were developed. The outcomes of this study may facilitate the bridge engineers to choose optimum design parameters such as girder types and spacing as well as number strands for a certain span length before the design of slab on PCI girder bridges.
{"title":"Design Optimization of PCI Girders: A Parametric Study","authors":"M. Jahjouh, S. Erhan","doi":"10.3233/brs-220203","DOIUrl":"https://doi.org/10.3233/brs-220203","url":null,"abstract":" This study investigates the effect of superstructure configuration on the optimum design of slab on Precast I (PCI) girder bridges. For this purpose, more than 20,000 bridge cases of varying superstructure configurations are considered to investigate the effects of various superstructure parameters such as girder spacing, span length, slab thickness and girder types on the optimum design of slab on PCI girder bridges. PCI girders are designed conforming to the AASHTO LRFD for flexure using stress limits at the service limit state, then checked at ultimate for flexure and shear using factored loads at the strength limit state. A modified harmony search optimization algorithm is used to obtain optimum bridge design parameters using standard AASHTO PCI girders according to these AASHTO LRFD requirements. Those girders are designed taking into consideration geometrical constraints, stress constraints and constraints related to the conformity of the design with the AASHTO LRFD code. Various sensitivity analysis are performed to investigate the effect of different geometrical factors on the design of the girders, and easy-to-use design aids were developed. The outcomes of this study may facilitate the bridge engineers to choose optimum design parameters such as girder types and spacing as well as number strands for a certain span length before the design of slab on PCI girder bridges.","PeriodicalId":43279,"journal":{"name":"Bridge Structures","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42721072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The use of integral abutments in bridges goes back many years to the late 1930’s in the United States. Over the years, integral bridges became more popular as more and more states built those bridges and more engineers became familiar with their design and construction. These bridges are being built in Europe since the 1980’s. An integral abutment bridge acts as a frame structure with a continuity connection between the superstructure and the substructure. The substructure is typically an integral cap supported on single row of piles that provides flexibility to accommodate thermal loads and displacements. The main advantage of integral abutment bridges is that they are built without expansion joints which eliminates maintenance costs and reduces construction costs. Because of the interaction between the soil and the integral abutment under the applied loads and the cyclic nature of thermal loads, the analysis and design of integral abutment bridges can be, in some cases, challenging especially when the designs falls outside the geometrical limits set by existing standards. This overview focus on field performance data reported in the literature and interpretation of this data. IT also highlights the needs for more test data during construction and for long term performance under cyclic thermal movements. Deck replacement requirements in integral abutments were investigated using analytical models and recommendations for deck replacement preparations are provided.
{"title":"An overview of integral abutments: Current practices, field monitoring and deck replacement measures","authors":"R. Vasconez, Aliaksei Kustau, H. Najm","doi":"10.3233/brs-220196","DOIUrl":"https://doi.org/10.3233/brs-220196","url":null,"abstract":"The use of integral abutments in bridges goes back many years to the late 1930’s in the United States. Over the years, integral bridges became more popular as more and more states built those bridges and more engineers became familiar with their design and construction. These bridges are being built in Europe since the 1980’s. An integral abutment bridge acts as a frame structure with a continuity connection between the superstructure and the substructure. The substructure is typically an integral cap supported on single row of piles that provides flexibility to accommodate thermal loads and displacements. The main advantage of integral abutment bridges is that they are built without expansion joints which eliminates maintenance costs and reduces construction costs. Because of the interaction between the soil and the integral abutment under the applied loads and the cyclic nature of thermal loads, the analysis and design of integral abutment bridges can be, in some cases, challenging especially when the designs falls outside the geometrical limits set by existing standards. This overview focus on field performance data reported in the literature and interpretation of this data. IT also highlights the needs for more test data during construction and for long term performance under cyclic thermal movements. Deck replacement requirements in integral abutments were investigated using analytical models and recommendations for deck replacement preparations are provided.","PeriodicalId":43279,"journal":{"name":"Bridge Structures","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48137357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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