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为研究P-Δ效应对圆弧削弱节点空间钢框架结构抗震性能的影响,采用ANSYS有限元结构分析软件建立空间钢框架计算模型。钢框架分析中分别考虑无轴压、均布面压力轴压和集中力轴压3种荷载工况,进行了低周往复荷载有限元模拟分析。对比分析了3种荷载工况作用下的滞回曲线、骨架曲线、退化曲线和耗能能力指标。分析结果表明:P-Δ效应对结构水平变形和承载力有较为明显影响,对结构有明显附加荷载作用,结构滞回环出现“负刚度”现象,加载刚度小于卸载刚度,并且滞回环包围面积有大幅度减小,说明P-Δ效应导致结构的耗能及延性均产生较大退化,结构抗震试验及分析中应充分考虑其不利影响。
In order to study the influence of P-Δ on the seismic performance of spatial steel frame structures with circular-arc weakened nodes, the finite element model analysis software ANSYS was used to establish the calculation model of the spatial steel frame. In the analysis of steel frame, three kinds of load conditions, ie no axial pressure, uniform surface pressure axial pressure and concentrated axial axial pressure, respectively, were considered, and finite element simulation analysis of low cycle reciprocating load was carried out. The hysteresis curve, the skeleton curve, the degradation curve and the energy consumption index were compared and analyzed under the three loading conditions. The results show that the P-Δ effect has a significant effect on the horizontal deformation and the bearing capacity of the structure, with obvious additional load on the structure. The phenomenon of “negative stiffness” appears in the hysteresis loop of the structure, the loading stiffness is less than the unloading stiffness, The results show that the P-Δ effect leads to a large degradation of the energy consumption and ductility of the structure, and its adverse effects should be fully considered in the structural aseismic test and analysis.