基于多尺度的高层钢框架梁柱节点疲劳分析

Fatigue Analysis of Beam-Column Node of High-rise Steel Frame Based on Multiple Scale

高层钢结构梁柱节点在地震交变往复荷载作用下发生低周疲劳破坏进而导致结构发生倒塌。因此,为了保证钢结构梁柱节点不发生疲劳破坏,有必要对梁柱节点以及节点域的疲劳特性进行分析研究。首先,利用多节点约束方法建立悬臂梁模型,验证多尺度建模方法;其次,基于Ansys建立一幢12层钢框架梁系有限元模型,掌握结构在地震作用下应力应变分布规律;在此基础上,利用多尺度建模方法,建立该框架结构多尺度有限元模型,详细分析钢结构梁柱的应力应变分布规律;最后,通过S-N曲线对局部梁柱节点的寿命进行预测分析。结果表明,钢框架梁柱节点以及节点域的应力分布比较集中,从而引起梁柱节点的局部破坏,最终导致整体钢框架的失效,在以后的设计中,应对梁柱节点的疲劳问题予以考虑。

High-rise steel structure beam-column node will cause the low-cycle fatigue failure under the influence of earthquake alternating reciprocating load and then lead to the collapse of structure. Therefore,in order to guarantee the steel structure beam-column node not causing the fatigue damage, it is necessary to analyze and study the fatigue characteristics of the beam-column node and the node domain. Firstly, the multi-node constraint method is used to establish the cantilever beam model and to verify the multi-scale modeling method. Secondly, the finite element model of a 12-floor steel frame beam system is established based on Ansys to master the rule of stress and strain distribution under earthquake action. On this basis, the multi-scale modeling method is used to establish the multi-scale finite element model of this frame structure so as to analyze the rule of stress and strain distribution of steel structure beam and column in detail. Finally,the lifetime of local beam-column node is predictively analyzed by S-N curve. The results show that the stress distribution of steel frame beam-column node and the node domain is more centralized thereby to cause the local failure of beam-column node, and lead to the failure of the whole steel frame in the end. The fatigue problem of the beam-column node has to be considered in the future design.