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考虑桥梁支座的作用,针对两跨连续梁桥的竖向碰撞问题,建立了梁-弹簧-杆连续体模型。采用瞬态波特征函数展开法和组合体瞬态内力法,推导了多次竖向碰撞问题的理论解,分析了桥梁支座对竖向碰撞的影响。研究结果表明:桥梁支座直接影响桥面与桥墩的局部碰撞接触刚度,显著影响竖向碰撞响应,包括碰撞次数、竖向碰撞力和碰撞位移响应等。桥梁支座对竖向碰撞具有显著的吸能减震效果,且影响竖向碰撞响应的基本特征,如次碰撞出现的频次和响应的频率。当近场竖向地震激励周期逼近桥梁的固有振动周期时,桥面上抛跳起,与桥梁支座产生剧烈竖向碰撞。由于调节桥梁支座的刚度可以改变桥梁的固有振动周期,因此,合理设计桥梁支座对于降低竖向碰撞的破坏作用,提高桥梁结构抵抗竖向地震的能力,具有重要的价值。
Considering the role of bridge support, a beam-spring-rod continuum model is established for the vertical collision of two-span continuous bridge. The theoretical solution of multiple vertical collision problems is derived by using the transient wave eigenfunctions and the transient internal force method. The influence of bridge abutment on the vertical collision is analyzed. The results show that the bridge abutment directly affects the local contact stiffness of bridge deck and abutment, and significantly affects the vertical collision response, including the number of collisions, the vertical impact force and the response of collision displacement. Bridge supports have significant energy absorption and damping effects on vertical impact, and affect the basic characteristics of vertical impact response, such as the frequency of secondary collision and the frequency of response. When the near-field vertical seismic excitation cycle approaches the natural vibration period of the bridge, the bridge throws violently and vertically and collides with the abutment of the bridge. Adjusting the stiffness of the bridge supports can change the natural vibration cycle of the bridge. Therefore, it is of great value to rationally design the bridge supports to reduce the destructive effect of the vertical impact and to improve the ability of the bridge structure to resist vertical earthquakes.