钢筋混凝土楼板连续倒塌的一种简化模拟方法

A SIMPLIFIED SIMULATION METHOD FOR PROGRESSIVE COLLAPSE OF REINFORCED CONCRETE SLABS

楼板作为框架结构的重要组成构件,显著影响结构抗连续倒塌性能。该文提出了一种新的钢筋混凝土楼板简化数值模拟方法,把楼板沿两个平面方向离散形成一个梁网,每个方向上的网络线采用纤维梁单元来模拟钢筋和混凝土的组合受力行为。其中,采用T/L形截面的纤维梁单元模拟楼板边缘区域的梁板交界节点,以考虑楼板对梁在连续倒塌小变形下弯曲受力以及破坏形态的影响;采用矩形截面的纤维梁单元模拟楼板的中心区域,以考虑楼板在大变形下发挥的薄膜拉力。采用这种方法不仅解决了以往用壳单元模拟刚度过高的问题,还大大提高了整体结构的运算效率。该文对T/L形截面异形柱和单双向楼板试验分别进行模拟,结果表明该简化方法能够高效准确的模拟钢筋混凝土楼板的大变形力学行为,为整体结构的抗连续倒塌分析提供了有力的工具。

Floor slabs are important components of frame structures which largely affect the structural progressive collapse performance. This paper presents a simplified numerical simulation method for reinforced concrete （RC） slabs. ARC slab is discretized along two directions transferring into a beam network. The meshes at each direction are simulated by fiber beam elements to consider the composite mechanical behavior of steel reinforcement and concrete. In this method, beam-slab joints at the edge area of slabs are simulated by fiber beam elements with T/L sections, by which the effects of slabs on the bending behavior and the damage mode of the beams under small deformation in progressive collapse are considered. On the other hand, fiber beam elements with rectangle sections are used to simulate the interior area of slabs, by which the tensile membrane action of slabs under large deformation can be considered. This method can not only avoid the high stiffness problem when using shell elements, but also greatly improve the efficiency of the calculation of the whole structure. Finally, existing tests on special-shaped columns （T/L cross sections）, one-way slabs and two-way slabs are simulated, respectively. The results show that the simplified method can efficiently and accurately simulate the reinforced concrete slabs under large deformation, providing a powerful tool for the simulation of progressive collapse analysis of whole structures.