基于梁单元的钢-混凝土混合结构非线性地震响应分析

Analysis of nonlinear seismic response of steel-concrete hybrid structures using beam element

钢桁架-钢筋混凝土管柱混合结构质量和刚度沿竖向分布不均匀。基于组合梁单元和合理计算参数的钢筋混凝土管柱模型,准确模拟荷载-位移关系,较好地解决了ANSYS在进行结构分析时模拟钢筋混凝土管柱的难点;对原型结构和试验结构进行模态分析和非线性地震响应分析,并结合抗震试验结果,分析动力性状,研究地震作用下A型架顶部和桁架处位移、桁架悬挑端竖向挠度、悬挑端下弦杆内力、A型架下部小柱轴力等动力响应问题。分析表明,有限元分析效果良好,第一阶振型为扭转,抗扭问题须重视;用组合梁单元模拟管柱,保证地震响应计算中位移输出的准确性,计算最大位移和试验一致,但计算峰值滞后;地震作用下A型架整体弯矩使桁架悬挑杆件内力变化剧烈,悬挑端挠度变化幅度增大,最外侧小柱轴力增大。根据分析结果,提出可供结构设计参考的建议。

Hybrid structure is composed of steel truss and reinforced concrete tubular columns. Its stiffness and mass is not uniformly distributed along the vertical direction. Reinforced concrete column load-displacement relationship was accurately simulated. Mode analysis and non-linear seismic response analysis on archetypal and experimental structures were conducted. Combining with the aseismic test results, the dynamic behaviors were analyzed. The dynamic responses of displacement at a shape structure top and the truss, vertical deflection at the truss cantilever end, lower chord internal force at the cantilever end, and small column axial force at a shape structure bottom under earthquake actions were studied. The 1st mode is torsion. Using column model based on combination beam element, the accuracy of displacement output is checked for seismic response calculation. The calculated maximal displacement agrees well with the experimental result, but the calculated peak lags behind. The internal force change of members at the truss cantilever end is sharp because of the moment of a shape structure under earthquake actions. The range of deflection change at the cantilever end is increased. Small column axial force at the outside piece is increased.