Testing and modeling for cyclic joint shear deformations in R/C beam-column connections

Abstract

In seismic analysis of moment-resisting frames, beam-column connections are often modeled with rigid joint zones. However, it has been demonstrated that, in ductile reinforced concrete (RC) moment-resisting frames designed based on current codes (to say nothing of older non-ductile frames), the joint zones are in fact not rigid, but rather undergo significant shear deformations that contribute greatly to global drift. The primary objective of this paper is to propose a rational method of estimating the nonlinear hysteretic joint shear behavior of RC beam-column connections and of incorporating this behavior into frame analysis. The authors tested four RC edge beam-column-slab connection subassemblies subjected to earthquaketype lateral loading; hysteretic joint shear behavior is investigated based on these tests and other laboratory tests reported in the literature. An analytical scheme employing the modified compression field theory (MCFT) is developed to approximate joint shear stress vs. joint shear strain response. A connection model capable of explicitly considering hysteretic joint shear behavior is then formulated for nonlinear structural analysis. The connection model is able to well represent the experimental hysteretic joint shear behavior and overall load-displacement response of the connection subassemblies.