配筋砌块砌体剪力墙归一化刚度衰减研究

Research on Normalized Stiffness Degradation of Reinforced-Block Masonry Shear Walls

目的研究在压弯剪复合受力状态下配筋砌块砌体剪力墙的归一化刚度衰减,确定墙体的刚度衰减规律.方法利用34片足尺全灌芯配筋砌块砌体剪力墙的低周往复荷载试验,将墙体按照破坏模式分为剪切型和弯曲型两种,选取截面厚度分别为190 mm、240 mm和290 mm的3种块型的墙体,基于试验得到的滞回曲线,计算得到在不同破坏模式下墙体的刚度,采用对初始刚度的归一化和对峰值点刚度的归一化两种方法分别计算刚度退化系数α0=Ki/K0和αm=Ki/Km.结果得到归一化刚度衰减方程,计算值与试验值吻合较好.刚度退化系数α0与Δi/Δ0曲线和αm与Δi/Δm曲线均满足指数衰减规律,建议指数方程中的衰减指数取-1.34更加合理.结论无论是剪切型还是弯曲型破坏墙体,各次试验中αm曲线的离散性更小,更加均匀、稳定,可以用αm曲线方程表示配筋砌块砌体剪力墙的刚度衰减规律.

This paper intends to investigate the normalized stiffness degradation of the reinforcedblock masonry shear walls under the combined action of compression,moment and shear,based on the tests of 34 full-scale fully grouted sample models subjected to lowcyclic reversed lateral loads.According to the failure mechanism,the sample models can be divided into shear-dominated andflexure-dominated walls. The cross-section width of block masonry was 190 mm,240 mm and290 mm in the tests. The normalized stiffness curves were derived from the hysteretic curves after the tests. The coefficient of stiffness degradation of walls was calculated by two methods,one is to be normalized by the initial stiffness,α0= Ki/K0,the other is by the peak stiffness,αm= Ki/Km,and the stiffness degradation equation of these walls was integrated based on different failure mechanisms. It is demonstrated that the stiffness degradation equation follows the exponential decay law; It is more reasonable that the attenuation exponent in an exponential decay equation is acquired-1. 34; furthermore,it can be shown that the dispersion of the αmcurves of all walls is much smaller and the equation for the αmcurves can be used for describing the stiffness decay lawof the reinforced-block masonry shear walls.