Polygonal loop model for hysteretic behaviour of frame structures with recycled aggregate concrete

Abstract

On the basis of shaking table tests on the recycled aggregate concrete (RAC) precast frame structure subjected to excitations of Wenchuan wave (WCW, 2008, N-S), El Centro wave (ELW, 1940, N-S) and Shanghai artificial wave (SHW), this study employed a new polygonal loop model (PLM) with its two core characteristics, that is, stiffness and strength degradation to describe the hysteretic behaviour of RAC frames. The implementation of the PLM model underwent different stages such as backbone curve, pivot points and unloading/reloading rules. The validation by shaking table tests on the precast RAC frame and application of the PLM to one cast-in-place RAC frame structure revealed that the hysteresis loops generated by the proposed PLM model not only traced the hysteretic trend but also fitted well with the tested hysteretic curves. Given these findings, it may be concluded that the new PLM model can be used to predict the seismic behaviour of RAC frame structures.