Analysis and Behavior of Precast Beam-to-Column Connections under Cyclic Loading

Abstract

This research focuses on investigating the behavior of hybrid beam-column connections with various detailing schemes to be used in precast moment resisting frames under cyclic loading, which leads to better understanding of their performance and safer seismic applications. To achieve this aim, an integrated experimental and numerical study was conducted. The experimental part consisted of reversed cyclic loading of precast concrete beam-column specimens with six different anchorage details used in beam element, as well as monolithically cast companion specimens. In the numerical part, a nonlinear finite element analysis (FEA) approach was proposed to reproduce the experimental response of a specific type of moment resisting precast concrete beam-column connection exposed to reversed cyclic load tests. Three-dimensional (3D) nonlinear finite element models were developed using the finite element software, ABAQUS to compare and validate the cyclic behavior of reference monolithic and precast hybrid beam-column connections against experimental work. The models include comprehensive examination of concrete and steel behavior up to failure. A modified Concrete Damage Plasticity model (CDP) that accounts for compression-softening and tension-stiffening effect was adopted for concrete in order to reproduce the typical cyclic behavior of cracked reinforced concrete. Kinematic Bilinear Elasto-Plastic nonlinear model was used to model all steel parts with the addition of bond-slip effect for all reinforcing bars embedded in concrete. Good comparison between finite element results and tested members has been achieved, which demonstrates the accuracy of the proposed finite element model despite the complexity of the investigated connections. All failure modes of the precast connections were captured from the developed finite element model, unlike experiments and compared with those of the corresponding monolithic connection. It was observed that simple detailing modifications highly influence failure modes of the connections and may result in major improvement of the connection performance in terms of strength and energy dissipation mechanism. This study concludes that precast connections have the potential to perform well under cyclic loading. Novel connection details were proposed to further improve the behavior under seismic loading and conclusively, a design procedure was developed.