大型铸钢节点极限荷载及破坏机理分析

Analysis of ultimate load and mechanisms of failure in large cast steel joints

结合成都某工程管桁架屋盖的大型铸钢节点,运用有限元技术采用线性强化弹塑性本构模型对铸钢节点进行极限状态分析。结果表明,铸钢节点在极限荷载下会产生很大的累积塑性应变;且随着塑性区的开展,节点应力极值位置与弹性阶段不同。在铸钢节点极限承载机理研究中,首次提出了采用速率型张量的大应变几何非线性问题;给出了铸钢节点破坏失效的判别标准;并指明铸钢节点设计必需进行极限状态分析才能确定其最薄弱位置,为正确认识铸钢节点的破坏形式、破坏机理以及铸钢节点设计提供依据。

Based on a project of pipe truss roof framing in Chengdu,the ultimate limit state analysis is performed on cast steel joints by using FEM,in which Linear hardening elastic-plastic constitutive model is considered. The results show that,the joint has a great accumulation of plastic strain in ultimate loads,and the point of maximum stress is different from that in elastic with the development of the yielding zone. The paper propoes to use rate-type tensor for the large strain geometric nonlinear problem,shows the criterion of failure formation,and indicates that its essential to apply limit state analysis to the determination of the weakest location on cast steel joint design,which provides basis for understanding the failure modes and failure mechanism of cast steel joint and the cast steel joint design.