考虑损伤累积效应的拱形立体桁架结构倒塌分析

以实际工程为背景,通过ABAQUS损伤材料子程序对拱形立体桁架结构进行连续倒塌分析,考虑了杆件失稳的影响,研究了该类结构在强震作用下的倒塌破坏机理和破坏模式。结果表明,强震作用下,拱形立体桁架结构杆件损伤不断累积,刚度逐渐退化,最终失效退出工作。损伤累积效应使杆件应力减小,应变增大,同时节点位移幅值增大。在地震波作用下,中间主桁架柱腹杆最先失效退出工作,随后失效区域沿主桁架平面外方向扩展并由柱脚发展至结构顶部。地震作用结束后,主桁架1/4跨度处腹杆以及部分长细比较大的柱腹杆发生失稳破坏。考虑杆件失稳的影响,将导致部分杆件提前失效,但对整个结构的破坏模式影响不大。

Collapse Analysis of Steel Trussed Arch Structure Considering Damage Cumulative Effect

Based on an actual project, the ABAQUS material subroutine considering damage cumulative effect and member buckling was adopted to analyze the collapse process of steel trussed arch structure. The failure mechanism and the failure mode of such structure under severe earthquake conditions were studied. The results indicated that, under the action of severe earthquakes, the cumulative damage increased and structural stiffness declined, which leading to the structure failure. The damage cumulative effect caused the decrease of the member stress and the increase of nodal displacement and member strain. Subjected to seismic waves, the webs at the columns of the middle main truss failed at first; then the failure region extended along the out-of-plane direction of the main truss and extended from the column foot to the top of structure. After the earthquake, the webs at the one-quarter point of the main truss and the webs at columns with large slenderness ratio buckled. It will lead to early failure of part members if member buckling is considered. However, it has little effect on the failure mode of structure.