竖向不规则钢结构水平侧向力分布模式与Pushover分析

Lateral load patterns and pushover analysis of vertically irregular steel structures

合理选取侧向水平力分布模式是Pushover分析中的一个关键问题。对于形状较为规则且基本振型起主要控制作用的结构,传统的水平侧向力分布模式对分析结果影响不大,得到的结构破坏方式也没有太大的差异。但是形状不规则且高阶振型影响不能忽略的结构则受水平侧向力分布模式的影响很大。针对竖向不规则多、高层结构侧向刚度突变的特点,从楼层质量、侧向刚度、振型参与系数等影响因素出发,提出了一种改进的水平侧向力分布模式。对一典型竖向不规则钢框架结构分别进行了不同侧向力分布模式下的Pushover分析,并与IV类场地典型地震波作用下的弹塑性时程分析结果进行了比较。计算结果显示,改进分布模式下的Pushover分析与时程分析结果最为接近,验证了所提模式的可行性。

It is a key step to properly select lateral load patterns in the Pushover analysis.Especially,when higher modes influence is important and the structure form is irregular.With considering the particularity of irregular structure,an improved lateral load pattern was developed based on some important factors,such as story mass,story lateral stiffness,and mode participation ratio.For a vertically typical irregular steel structure,the pushover analyses of the structure under different patterns of lateral load were conducted and the results were compared with that from elastoplastic time history analysis.The results indicate that the soft story can be accurately detected in pushover analysis through the proposed lateral load pattern.