考虑钢梁翼缘断裂的组合框架抗震性能分析

基于钢-混凝土组合框架抗震性能试验,考虑材料、几何及接触非线性,采用Msc.Marc建立了钢-混凝土组合框架的有限元分析模型.有限元模型中引入基于应变的钢梁翼缘断裂准则,能够较好地模拟钢梁翼缘的断裂现象.有限元模型的整体及局部计算结果均与试验结果吻合良好.在试验验证的基础上,对有限元模型进行参数分析,研究了楼板宽度、剪力连接程度、轴压比等参数对钢-混凝土组合框架刚度、强度及延性的影响.研究发现,在试验及3维建模中,为了准确反映楼板对组合框架抗震性能的影响,楼板宽度至少应取为跨度的1/4;轴压比对组合框架延性有较大影响;楼板厚度、剪力连接程度对组合框架抗震性能影响较小.结合相关组合结构设计规范,讨论了各项参数的合理取值,对组合框架抗震设计提出了建议.

Seismic Performance of Steel-concrete Composite Frames Considering the Fracture of Beam Bottom Flanges

Based on the test of steel-concrete composite frame,the refined 3-D finite element(FE) modeling of steel-concrete composite frame was proposed by using Msc.Marc to gain a better understanding of the structural behavior of the composite frames.A number of material nonlinearities and contact nonlinearities,as well as geometry nonlinearities,were taken into account.Strain-based fracture criterion was adopted in the FE model to simulate the fracture of beam flange.The global and local behavior of the FE analysis models agreed well with those of the test specimens.Parametric studies were conducted on the basis of the refined FE model.The analyzed parameters included slab width,shear connection degree,axial force ratio,etc.The influences of these parameters on the behavior of the composite frame in terms of stiffness,strength and ductility were studied.It was suggested that the concrete slab width should be taken at least as a quarter of the beam span in the 3D FE model or in the test specimen to accurately evaluate the impact of the slab action.The axial force ratio had a great impact on the ductility of composite frame,while the thickness of the slab and shear connection degree had little effect on the seismic behavior of the composite frame.And some ideas for the corresponding design provisions were proposed.