鉄筋コンクリート柱・はり外部接合部を含む架橋の靭性評価

Abstract

Beam-column joints of reinforced concrete highrise building have been recently paid much attention as relatively weak links under severe earthquake attacks, because of the strengthening of the aseismic reinforcing for beam and column members. The key point of the aseismic performance of the joint is to ensure and maintain the energy absorbing capacity of the plastic hinges of the adjoining members without any shear or anchorage failure in the joint core. In this paper, the authors focused on the exterior beam-column joint to make clear the discussion, and carried out the cyclic reversed loading tests of eighteen exterior beam-column subassemblages. Column axial force, amount of joint hoop, existence of intermediate column bars and moment capacity of column were selected as the experimental variables. On the basis of the thorough consideration of the test results, the following major remarks were obtained. 1. The ratio of shear stress at yielding of beam and shear strength in the joint was designed less than 0.5 for every subassemblages. Nevertheless, ten of eighteen specimens resulted in joint shear failure due to the repetition of reversed loading after the yielding of beam. 2. The ductility of the subassemblages increases with the increase of column axial force and amount of joint hoop. The existence of intermediate column bars is also effective to increase the ductility of subassemblages. 3. The critical cumulative ductility factor, at which the value of shear distortion reaches 0.8×10^<-2>, was quantified as a function of the experimental variables, and was ascertained to be very effective to evaluate the aseismic ability of the exterior beam-column subassemblages.