UBC Theses and Dissertations
Evaluating the performance-based seismic design of RC bridges according to the 2014 Canadian Highway Bridge Design Code Ashtari, Sepideh
The 2014 edition of the Canadian Highway Bridge Design Code, CSA S6-14, has adopted a performance-based design approach for the seismic design of lifeline and major-route bridges in highly seismic zones. This addition offers many opportunities as well as some challenges with regards to implementing the CSA S6-14 performance-based design provisions in practice. This thesis aims to identify these challenges through a critical review of the CSA S6-14 performance-based design provisions and to address a number of them within the scope of the thesis. The motivation behind conducting the present study is to prepare a reference document for engineers to better comprehend and implement the new provisions in practice. The focus of the thesis is on the performance-based design of new reinforced concrete bridges with ductile substructures. The addressed challenges are related to CSA S6-14 performance verification framework, calibration of performance criteria, and appropriate numerical models to evaluate the established performance criteria. A deterministic and a probabilistic framework are recommended to be used with the CSA S6-14 performance-based design approach. The applications of each of the frameworks are demonstrated through two detailed case studies and the advantages and disadvantages of each framework are discussed. The performance criteria of the code are compared against the recommended criteria in the literature and other design guidelines. Moreover, the strain limits of the code are examined to predict the damage to a number of tested reinforced concrete bridge columns. A thorough comparison of the CSA S6-14 and the updated strain limits of the BC MoTI Supplement to CSA S6-14 is presented. Finally, common modelling techniques for reinforced concrete structures including distributed and concentrated plasticity models are employed to predict the response of a number of tested bridge columns. Mesh-sensitivity issues due to the localization of plastic strains at critical sections or elements of distributed plasticity models are discussed and the methods to rectify the issue are presented and compared. A simple solution is proposed to eliminate the post-processing effort that is required to verify the strain limits of the code in distributed plasticity models, for which material model regularization is used to deal with the mesh-sensitivity issue.
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