地震爆炸联合作用下桥梁响应与损伤的数值模拟

Numerical simulation of the response and damage of girder bridges subjected to the combined action of earthquake and blast

为研究地震和爆炸2种极端荷载联合作用下桥梁结构的动力响应及损伤规律,基于某30 m跨径预应力钢筋混凝土简支梁桥,以ANSYS/LS-DYNA有限元软件为分析平台,提出了考虑地震、爆炸联合作用的方法,建立了简支梁桥在地震、爆炸联合作用下的有限元模型。选取了EL Centro地震波和250 kg TNT炸药分别作为地震和爆炸荷载施加于结构,分析了不同桥梁结构构件的损伤和动力响应,总结了地震、爆炸联合作用下结构的损伤和失效类型。结果表明:地震、爆炸联合作用于主梁时,主梁的纵向位移有所增加,可能导致落梁,需设限位装置;地震、爆炸联合作用于桥墩时,桥墩的损伤面积和损伤深度增大,墩底甚至被剪断,失去承载能力;不同方向的地震、爆炸联合作用下,桥墩最大损伤发生的时间和损伤程度不同。

To obtain the dynamic response and damage law of bridges subjected to the combined action of earthquake and blast,a finite element(FE)model of one 30 m-span simply supported prestressed reinforced concrete girder bridge under the combined action of earthquake and blast was established using the software ANSYS/LS-DYNA as an analytical platform.A new simulation method that considers the combined action of seismic and explosive loads was utilized.Seismic wave EL Centro and a 250 kg TNT explosive were selected as applied loads acting on the structure.The damage condition and dynamic response of various bridge structural members were analyzed,and the damage law and failure type of structures under the combined action were summarized.The results show that the longitudinal displacement of the main girder increases and beam falling may occur under the combined action.The use of displacement limitation devices is suggested.When piers are subjected to the combined action,the damage area and the depth of piers will increase,and a fatal injury of the base being cut off may occur,causing failure of the carrying capacity.The occurrence time of the most severe pier damage and the damage severity vary under different loading directions.