底框剪-砌体房屋抗震性能研究

Seismic Performance of Masonry Building with RC Framed Lower Floor

目的研究底框剪-砌体房屋的抗震性能以及应用于7度区时的合理刚度比、框剪层地震剪力增大倍数、房屋总高度(层数)等问题.方法采用模拟地震振动台试验和非线性分析方法对一底两层框剪-砌体房屋模型分别进行模拟地震振动台试验和非线性分析.还对一底框剪砌体房屋进行大量的非线性分析.结果检验了四折线恢复力计算模型和计算参数的合理性;通过对底框剪砌体房屋的计算分析,得出底框剪-砌体房屋的抗震能力与场地土密切相关.结论对Ⅰ-Ⅲ类场地,底一层框剪-砌体房屋的抗震能力优于全砌体房屋,底两层框剪-砌体房屋又优于底一层框剪-砌体房屋;对Ⅳ类场地,三种房屋的抗震能力相当.对于7度区,底框剪-砌体房屋砌体层与相邻的底框剪层的弹性侧向刚度比不宜大于2.5;房屋的总高不宜超过21 m(七层).

In the paper earthquake simulation shaking table test of masonry buildings （MBs） with or without RC framed lower floor （LF） and associated nonlinear dynamic response analysis are described. In the analysis the skeleton curve characterizing the interstory restoring forcedisplacement relationship of MB consisting of four linear segments was used, and the values of the relevant characteristic points on the curve were suggested. The good agreement of the analytical results with the experimental results shows that the proposed skeleton curve and the values of the relevant parameters are appropriate. To achieve a better understanding of the seismic performance of three kinds of MBs, including MB with one LF, MB with two LFs and MB without LF, a great number of nonlinear dynamic response analyses were conducted. In the analyses 16 earthquake ground accelerations recorded from different soil site conditions were used as the input motions. Numerical results show that the seismic performance of ME with LF（s） greatly relates with the site conditions. For Ⅰ-Ⅲ site classes the MB with LF（s） exhibits higher seismic resistance than the whole MB （i. e. MB without LF）, and the MB with two LFs exhibits higher seismic resistance than that with one LF. For Ⅳ site class three kinds MBs considered have comparable seismic resistance. Besides, from the dynamic response analysis a rational story stiffness ratio of lowest masonry floor and its adjacent LF of within 2,5 and the maximum permissible total height of 21m, or the maximum permissible story number of seven are suggested for region of seismic intensity of Ⅶ.