基于能量法组合梁倒塌工况下的抗力分析

框架结构在竖向承重构件突然发生破坏的情况下主要通过两个抗倒机制防止连续倒塌的发生,分别为小变形状态下的梁机制以及大变形状态下的悬链线机制.组合楼板由于平面刚度大,可以显著提高框架结构的抗倒性能.将混凝土楼板-钢框架结构简化为组合梁结构进行分析.对已有研究得到的抗力曲线进行适当简化,并运用能量法分析抗倒各个阶段的受力特征以得到曲线各个阶段的表达式.随后应用大型有限元分析软件ANSYS对理论公式的可靠性进行算例验证,说明提出的分析方法较为合理,同时可以发现楼板对结构抗倒有明显的的加强作用.

ENERGY ANALYSIS OF THE RESISTANCE OF STEEL-CONCRETE COMPOSITE BEAM IN THE CASE OF THE PROGRESSIVE COLLAPSE

Frame structures are mainly designed to prevent the progressive collapse through two resistance mechanisms under the condition of sudden destruction of vertical bearing components, including the beam mechanism under a small deformation condition and the catenary mechanism under a large deformation condi-tion. The large planar stiffness of the composite slab can significantly improve the resistance of the progressive collapse of the structures. This paper simplifies a concrete floor-steel frame structure into a steel-concrete composite beam structure. The structure resistance curve obtained by previous researches is simplified. The mechanical characteristics in various stages during the progressive collapse are analyzed to obtain formulas of the resistance curve at every stages by using the energy method. Subsequently, the reliability of the proposed formulas is validated against a case study of an example by using the large-scale finite element analysis software ANSYS, and a good agreement is observed. It is shown that the slabs can greatly strengthen the progressive collapse resistance of the structures.