轻钢结构抗风极限承载力的三维精细分析

3D REFINED ANALYSIS OF WIND-RESISTANT ULTIMATE BEARING CAPACITY OF LIGHT-WEIGHT STEEL STRUCTURES

为研究既有门式刚架轻钢厂房结构的抗风性能和极限承载力,以我国东南沿海某轻钢厂房为背景,采用精细板壳单元和面外杆件单元建立三维整体有限元模型,分别按中国和美国相关规范的荷载组合施加风荷载,对厂房结构进行了弹塑性和大变形的非线性极限承载力分析,获得了承重结构的抗风安全冗余度系数以及达到极限状态时的破坏模式。结果显示,刚架按国内规范的风荷载作用下的安全冗余度大于美国规范的相应值;两者的破坏模式均为刚架的局部屈曲模式,但前者的局部屈曲集中于单榀刚架近屋脊梁段与迎风梁柱节点的多个区域中,而后者则发生于多榀刚架的同一梁柱节点处,呈现出空间化的分布特征,且发生时间早于前者。

In order to investigate the wind-resistant performance and ultimate bearing capacity of existing light-weight steel portal frame industrial building structures, an actual light-weight steel industrial building located at the southeast coastal area of China was taken as an example and a refined shell element and out-of-plane bar element-based finite element model were established. The wind load combinations proposed by the Chinese and American specifications were applied to the structure and nonlinear ultimate analysis in consideration of elastic-plasticity and large deformation to find out the wind- resistant safety redundant factors and the ultimate limit-state failure modes. The obtained results indicated that the degree of safety redundancy of the frame under the wind loads determined by the Chinese specification was higher than that by the ASCE specification. The failure modes under the two kinds of loading were both the local buckling failure within the frame. However the local buckling of the former occurred on the two regions of a single frame, one was the beam section near the ridge and the other was the windward beam-column joint. On the contrary, the latter occurred in the same beam-column joints among several frames, showing a space distribution feature and an earlier occurrence time.