考虑梁板柱空间协同效应RC框架“强柱弱梁”抗震设计效果非线性仿真分析

Nonlinear simulation analysis on “strong-column-weak-beam” seismic design effect considering beam-slab-column spatial collaboration of RC frame structure

采用三维实体退化虚拟层合单元非线性有限元分析法,考虑梁板柱空间协同效应,经对一水平荷载作用单跨单层RC空间框架试验和一双跨四层RC空间框架底层边柱失效竖向倒塌试验进行模拟分析并与其试验结果对比验证之后,对按现行规范设计抗震等级二级和三级的双跨六层RC空间框架模型进行非线性有限元分析与研究,得出梁板空间协同经历"全开间T形截面"整体抗弯向"T形翼梁"+2"板带"抗弯机制转变;下部框架梁先行出铰,加快底层框架柱塑性铰出现,进而导致上部框架柱弯矩增大;抗震等级一级、二级RC框架能够达到"强柱弱梁"预期效果,而三级、四级框架则不能完好或不能实现"强柱弱梁"抗震设计机制等研究结论。

The nonlinear finite element method based on degenerated three-dimensional solid virtual laminated element theory was introduced considering the spatial synergy of beam-slab-column. The validity and efficiency of the method were proved by analysis on a single-span and single-layer RC spatial frame experiment and bottom side column collapse failure test of a two-span and four-layer RC spatial frame under horizontal load. According to the current Chinese codes,two-span and six-story RC spatial frame models of seismic grade 2 and grade 3 were analyzed respectively by the method. Analysis results are concluded that the bending mechanism of beam-slab-column spatial collaboration has experienced the transformation from＂whole span T-section＂to＂T-shaped spar＂ ＋ 2 ＂plate-strip＂; the plastic hinges of frame beam in the lower layer first appeared,which accelerates appearance of the plastic hinges of the bottom frame column,and then leads to the increase of the bending moment of frame column in the upper layer. RC frames of seismic grade 1 and grade 2 can achieve the excepted effect of ＂ strong-column-weak-beam＂,while RC frames of seismic grade 3 and grade 4 can not fully or can not realize the ＂ strong-column-weak-beam＂ seismic design mechanism.