Performance of reinforced concrete edge beam-column-slab connections subjected to earthquake loading.

摘要

Beam-column connections are critical regions in reinforced concrete (RC) moment-resisting frame (MRF) structures designed to endure strong earthquakes. Since the mid-1964s, numerous experimental and analytical studies have been conducted to investigate the behavior of RC beam-column connections subjected to seismic loading and to establish adequate guidelines for design. However, only a few RC eccentric beam-column connections have been tested to date. Moreover, all of the eccentric specimens reported so far in the literature did not include floor slabs that are monolithically cast with beams and columns in real RC construction. Therefore, an experimental investigation was conducted consisting of four 2/3-scale RC edge beam-column-slab subassemblies (two concentric and two eccentric connections) tested under quasi-static cyclic lateral loading. The tests explored the effect of eccentricity between beam and column centerlines, the edge-beam width, and the effect of floor slabs, on the performance of edge beam-column-slab connections subjected to earthquake loading.; In seismic analysis of MRFs, beam-column connections are often modeled with rigid joint zones. However, it has been demonstrated that, in ductile RCMRFs 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. Therefore, the "rigid joint" assumption may result in misinterpretation of the global performance characteristics of frames and could consequently lead to miscalculation of strength and ductility demands on constituent frame members. The primary objective of the analytical investigation was to propose a rational method of estimating the hysteretic joint shear behavior of RC connections and of incorporating this behavior into frame analysis. Nonlinear hysteretic joint shear behavior was investigated based on the author's tests and many other laboratory tests reported in the literature. An analytical scheme employing the modified compression field theory (MCFT) was developed to approximate joint shear stress vs. joint shear strain response. A connection model capable of explicitly considering hysteretic joint shear behavior was then formulated for nonlinear structural analysis. The connection model was able to well represent the experimental hysteretic joint shear behavior and overall load-displacement response of the connection subassemblies.