竖向及水平地震作用下PSRC空腹桁架转换结构抗震性能分析

Seismic performance analysis of frame with PSRC vierendeel truss transfer story under vertical and horizontal ground motion

在“强转换”设计原则的基础上,提出预应力型钢混凝土(简称PSRC)空腹桁架转换层框架结构多道防线的划分和内力调整的具体方法:空腹桁架下弦梁和转换柱为最后一道防线;其次是转换层桁架中腹杆、上弦梁以及与其相连的上层框架柱;首道防线是转换层其他上抬框架梁柱。采用OpenSEES软件建立多榀有限元算例模型,进行水平与竖向地震共同作用下的弹塑性时程分析,研究其抗震性能以及竖向水平分量变化(V/H=0、0.65、1.2)产生的影响。研究结果表明:在罕遇及极罕遇地震水准下(V/H=0.65),结构可以避免整体和局部破坏,结构形成以上抬框架梁为主的混合耗能机制,总体实现了多道防线设防的设计思想。随着地震动竖向分量的增加,其影响主要表现在桁架下弦挠度显著增加,当竖向地震动较大时,其对上抬构件内力的附加影响应予以考虑。

Based on the design principle of“strong transformation”,a multi-lines defense seismic fortification method has been proposed for the frames with prestressed steel reinforced concrete(PSRC)vierendeel truss transfer story.In this method,the transfers columns and lower chord of transfer truss are designed as the last defense line.The second line includes the frame columns joined with transfer story,the upper chord and the middle web members of the transfer truss.Finally,the other columns and beams upon transfer story are the first line.In this study,firstly,the OpenSEES software was used to set up a series finite element models.Then the elastic-plastic time history analysis was finished under the horizontal and vertical earthquakes to study the basic seismic performance and the influence of the difference vertical motion(V/H=0,0.65,1.2).Results show that the structure can avoid the overall and partial damage under rare and very rare earthquake level(V/H=0.65).And a“beam-column mixed hinge mechanism”can be formed to dissipate energy mainly relying on the beams upon transfer story.The target of multi-lines defense seismic fortification has been realized.On the other hand,with the increase of the vertical component of the ground motion,its influence is focus on the increase of the lower chord deflection.