基于材料损伤的钢板加固半刚性组合节点抗倒塌性能分析

当结构中竖向承重构件发生破坏后，节点的抗倒塌性能决定了荷载是否能可靠地传递给相邻结构构件，避免结构出现连续倒塌。为了提高节点的转动能力和抗倒塌能力，设计了一种钢板加固的半刚性组合节点，提出其理论模型，并推导相应的变形公式，建立基于材料损伤的有限元分析模型对理论模型进行验证，并对该组合节点的抗倒塌性能进行分析。结果表明：钢板加强的节点并没有影响结构的前期性能，而是使结构提前进入过渡阶段，并且明显增大了结构的极限位移和极限荷载；该节点的理论模型及相应的变形公式可以精确预测钢板参与工作时对应的节点竖向位移；钢板两端连接点的初始距离和钢梁高度决定了钢板参与受力的时刻；采用类似具有“延时”作用的柔性组件可以起到与钢板相同的加固效果。

Study on anti-collapse performance of semi-rigid composite joint strengthened by steel plate considering material damage

When gravity members in a structure are damaged, the anti-collapse performance of the joints determines whether the load can be reliably transferred to the adjacent structural members and whether progressive collapse of the structure can be avoided. In order to improve the rotation capacity and anti-collapse performance of the joints, a semi-rigid composite joint strengthened by steel plate was designed. A theoretical model and a deformation prediction formula of the joint were proposed. A finite element model considering material damage was developed to validate the theoretical model, and the anti-collapse performance of the composite joint was analyzed. The results show that the joint strengthened by steel plate has no significant effect on the early performance of the structure, but the structure advances into the transient stage earlier, and the ultimate displacement and ultimate load of the structure are remarkably increased. The theoretical model and the corresponding deformation formula can accurately predict the vertical displacement of the joint when the steel plate contributes to load carrying capacity. The initial distance of the connecting point at both ends of the steel plate and the height of the steel beam determine the moment when the steel plate starts to take load. The same retrofitting effect can be achieved with flexible components that have a ‘delay’ effect.