地震作用下梁体碰撞间隙宽度的概率分析方法

为了表征地震动随机性对梁体碰撞间隙宽度设计的影响，基于随机振动理论和矩阵系统可靠度运算方法提出一套评价桥梁系统间隙需求宽度的概率方法。首先，建立空间地震激励下的桥梁碰撞间隙需求概率模型；其次，建立了桥梁梁体碰撞的有限元模型，推导了震级与梁体间隙宽度超越概率的关系；最后，基于矩阵系统运算方法得到桥梁系统所有碰撞处（梁体与梁体、梁体与桥台）各碰撞间隙宽度和桥梁系统碰撞概率关系。研究表明：随着震级增加，间隙宽度需求成非线性增加；梁体-桥台碰撞需求基本一致，梁体-梁体的碰撞概率比梁体-桥台碰撞概率要约大20%；在震级为7时，三个碰撞点均发生碰撞的超越概率约为63%，至少两处发生碰撞的概率为95%，至少一处发生碰撞的概率为100%。

PROBABILITY ANALYSIS OF POUNDING SEPARATION DISTANCE OF BRIDGES SUBJECTED TO EARTHQUAKE EXCITATIONS

To characterize the influence of randomness of ground motion on the pounding separation distance, based on the stochastic vibration theory and the matrix system reliability computing method, a probabilistic approach was proposed to evaluate the required separation length of a bridge system. Firstly, a probability model was developed on pounding separation distance of a bridge under spatially varying seismic loads. Secondly, the finite element model of the bridge pounding system was built, and the conditional exceedance probability relation of the separation distance between the adjacent bridge decks and the earthquake magnitude was obtained. Finally, by using the matrix system reliability computing method, the pounding probability relation of the bridge system and separation lengths of all pounding points (deck-deck and deck-abutment) was obtained. Some important conclusions were drawn that the demand of the separation length nonlinearly increases with the increase in the magnitude; the demand of pounding separation distance on deck-abutment at two ends of employed bridge was almost in agreement and the pounding probability at deck-deck pounding point was about 20% larger than that at deck-abutment pounding point. At a magnitude of 7, the probability of all three pounding points triggered was about 63%, the probability of at least two collision was 95%, and the probability of at least one collision was 100%.