EVALUATING SHEAR STRENGTH OF RC INTERIOR WIDE BEAM COLUMN JOINTS UNDER SEISMIC ACTION

In this paper, applicability of the RC beam-column joint nominal shear strength specified in codes of practice, including ACI 318-08, NZS 3101and EN 1998-1, to the interior wide beam-column joints is evaluated. This is particularly important because the code provisions were only developed for conventional beam-column joints that should be very different from those in a wide beam system. The results of all past published experimental studies on interior wide beam-column joints are collected. The measured joint shear force for all tested specimens are calculated by three codes provision and results are compared with the related specific codes limitation to the joint nominal shear strength. It is shown that the actual joint shear force exceeds the ACI 318-08 limit in most cases, but these joints do not encounter shear failure or shear strength degradation within the joint core. This indicates that the limit specified in ACI318-08 is conservative when applied to wide beam-column joints. A model is proposed based on the strut-and-tie concept to consider the effect of wide beam on the shear capacity of the joint. The joint nominal strengths are calculated using the ACI approach with the proposed effective joint area and then compared with the experimental results. Good agreements are found. The impact of this modification on ACI approach is efficiently on the accurate design of the wide beam-column joints under strong seismic actions.