大跨越钢管混凝土输电塔地震作用弹塑性分析

利用静力和动力两种方法研究了一个大跨越钢管混凝土输电塔在地震作用下的弹塑性力学性能，包括：1) 建立了精细的输电塔和塔线体系两种有限元模型以及输电塔材料的非线性模型；2) 将由振型分解反应谱法得到的结构底部剪力按第一阶振型分配到有限元模型的各个节点上，一步步增加节点力，使材料逐渐进入塑性状态直到计算不能收敛为止。静力分析表明：结构失效是由于薄壁钢管单元失效造成的，而钢管混凝土单元还没有失效，结构的极限荷载由薄壁钢管单元决定；3) 利用时程法进行罕遇地震下的输电塔弹塑性分析。动力分析表明：在地震作用下，塔上许多单元很快就进入了塑性，在最后时刻，有一定数量的薄壁钢管单元已经破坏，但钢管混凝土单元没有出现破坏的情况，该塔能实现“大震不倒”的目标。两种方法都显示塔的中部是结构的薄弱处。

ELASTIC-PLASTIC ANALYSIS OF A LONG-SPAN CONCRETE FILLED STEEL-TUBE TRANSMISSION TOWER UNDER EARTHQUAKE ACTION

The elastic-plastic analysis of a long-span Concrete Filled Steel-Tube(CFST) transmission tower under earthquake actions is studied by the static method and the dynamic method,including: 1) fine FEM models of a CFST tower and a tower-line system are built and the nonlinear material models including steel-tube and CFST are also modeled.2) shear forces on supports obtained by a mode-decomposition response spectrum method are distributed at all nodes based on the structural first-order mode value and then the nodal loads increase step by step in order to impel materials into plastic status until calculation cannot converge.Static analysis shows there are some steel-tube elements failed but no any CFST element failed and the limit load is decided by the steel-tube elements.3) a seismic record is selected to analyze the seismic elastic-plastic behaviors of the tower by a time-history analysis method.The dynamic analysis shows a lot of elements enter the plastic status soon after earthquake action and there are some steel-tube elements failed but no any CFST element failed at last time,so the tower can achieve the goal: no collapse in the big earthquake.The two methods both show the weakest part is in the middle of the tower.