Joint shear behavior of reinforced concrete beam-column connections subjected to seismic lateral loading

Beam-column connections have been identified as potentially one of the weaker components of reinforced concrete moment resisting frames subjected to seismic lateral loading. Well-established knowledge of RC joint shear behavior is necessary because severe damage within a joint panel may trigger deterioration of the overall performance of RC beam-column connections. In this research, a more systematic understanding of RC joint shear behavior has been achieved by completing the following tasks.; An extensive experimental RC beam-column connection database (of 341 subassemblies in total) was constructed. RC joint shear behavior (joint shear stress v. joint shear strain) was described as an envelope curve by connecting key points displaying the most distinctive stiffness changes. At the identified key points, qualitative assessment on influence parameters on RC joint shear behavior was performed. Then, RC joint shear strength models were developed using the constructed experimental database in conjunction with a Bayesian parameter estimation method. For diverse types of RC beam-column connections, a unified joint shear strength model was constructed and simplified to be applicable for practical design situation. The improved performance of the proposed model was assessed by comparison with the code-based models and other models found in the literature. A modified AD 352R-02 joint shear strength model was also constructed by using the Bayesian parameter estimation method based on the design concept of the AO 352R-02. A simple and unified RC joint shear deformation model was also developed following the established procedure to suggest the simple and unified RC joint shear strength model. Full RC joint shear behavior models were constructed by employing the Bayesian method at each key point and also by adjusting the simple and unified joint shear strength and deformation models for maximum response. The improved performance of the suggested simple and unified joint shear behavior model was evaluated by comparison with other models found from literature. Finally, the Parra-Montesinos and Wight model was modified to improve its reliability by updating the key relation between principal strain ratio and joint shear deformation.