地震作用下钢管混凝土格构式高墩—桁式梁轻型桥粱行车安全性分析

发布时间：2018-07-24 09:19

【摘要】：钢管混凝土格构式高墩—桁式梁轻型桥梁属于新型的组合桥梁。干海子大桥作为国内首座该类型桥梁,其活载与恒载的比重比一般桥梁大,同时该桥墩高梁长、结构新颖、构造复杂,使得该桥抗震性能与普通组合结构不同。由于该桥位于强震到弱震活动过渡带,地震基本烈度较大,在强震作用下,有可能导致主梁产生过大的位移和振动,影响行驶车辆的安全。因此,本文对地震作用下干海子大桥车桥动力响应进行分析,探讨地震作用下高墩桥梁的行车安全性。本文的主要工作和得到的主要结论为：(1)基于考虑路面不平整度的车桥相互作用的耦合运动方程,考虑地震荷载的作用,建立了地震作用下车桥相互作用的耦合计算方法。将地震作用下车桥相互作用的耦合计算方法添加到已开发的程序NL_Beam3D中,实现了地震作用车桥系统相互作用的耦合计算。(2)与实桥荷载试验和地震模拟振动台缩尺模型试验进行了比较分析。结果表明：有限元分析得到的振型与两个试验得到的振型一致,有限元计算得到的面内、面外基频与试验得到的结果接近,误差在5%以内；移动车辆作用下第20跨主梁下弦杆动挠度有限元计算结果与实桥荷载试验的实测值较接近；在E1地震作用下,实桥有限元计算得到的位移时程曲线形状与振动台试验结果一致,实测位移幅值与理论位移幅值近似满足1/82的相似比关系,从而确认了本文建立的计算方法和编制的程序的正确性。(3)在最不利方向输入E1地震,桥梁主要以横向前几阶对称振型振动为主。采用车辆侧倾指标对行车安全进行的评价可以看出,桥梁横向最大加速度均小于车辆倾覆指标阀值,故E1地震作用下桥上行驶的车辆不会发生侧倾；相应的各桥墩墩顶最大位移,与《公路钢管混凝土桥梁设计与施工指南》规定的H/300限值相比,除8#墩外,其余墩均能满足要求。(4)通过逐级加大地震强度的方法分析干海子大桥的行车安全性。结果表明,第一、二联分别在地面峰值加速度PGA为0.17g(E1地震动)和0.26g(1.53倍E1地震动)时个别墩墩顶横向位移已超过了H/300的限值,但重型货车没有发生侧倾；重型货车可能发生倾覆时第一、二联对应的PGA分别为0.23g(1.35倍E1地震动)和0.32g(1.88倍E1地震动),此时最大墩顶横向位移与墩高之比分别为1/178和1/198,均大于《公路钢管混凝土桥梁设计与施工指南》规定的限值1/300,说明该指南对桥墩墩顶位移的限制比较严格。
[Abstract]:Concrete-filled steel tubular latticed high piers-truss beam light bridge is a new type of composite bridge. As the first bridge of this type in China, the proportion of live load and dead load of Qianhaizi Bridge is larger than that of ordinary bridge. At the same time, the bridge pier is long, the structure is novel and the structure is complex, which makes the seismic performance of the bridge different from that of the ordinary composite structure. Because the bridge is located in the transition zone from strong earthquake to weak earthquake, the earthquake intensity is large. Under the action of strong earthquake, the bridge may cause excessive displacement and vibration of the main beam and affect the safety of the driving vehicle. Therefore, the dynamic response of vehicle-bridge of Qianhaizi Bridge under earthquake is analyzed in this paper, and the driving safety of high-pier bridge under earthquake is discussed. The main work and conclusions are as follows: (1) based on the coupled motion equation of vehicle-bridge interaction considering road roughness and considering the effect of seismic load, the coupling calculation method of vehicle-bridge interaction under earthquake action is established. The coupling calculation method of vehicle-bridge interaction under earthquake action is added to the developed program NL_Beam3D. The coupling calculation of vehicle-bridge system interaction under seismic action is realized. (2) the results are compared with those of real bridge load test and seismic simulation shaking table scale model test. The results show that the vibration modes obtained by finite element analysis are consistent with those obtained by two tests. The in-plane, out-of-plane fundamental frequencies obtained by finite element analysis are close to those obtained by experiments, and the error is less than 5%. Under the action of moving vehicle, the finite element calculation results of the dynamic deflection of the chord under the 20th span main girder are close to the measured values of the real bridge load test, and the shape of the displacement time history curve obtained by the finite element calculation of the bridge under the E1 earthquake is consistent with that of the shaking table test. The measured displacement amplitude and the theoretical displacement amplitude approximately satisfy the similarity ratio of 1 / 82, thus confirming the correctness of the calculation method and the program developed in this paper. (3) the E1 earthquake is input in the most disadvantageous direction. The bridge is mainly based on the first several transversal symmetrical vibration modes. Using the vehicle roll index to evaluate the driving safety, it can be seen that the maximum lateral acceleration of the bridge is less than the threshold value of the vehicle overturning index, so the vehicles travelling on the bridge under E1 earthquake will not roll; The corresponding maximum displacement of the piers is compared with the limit of H / 300 specified in the guidelines for the Design and Construction of concrete filled Steel Tube Bridges, except for the 8# piers. The rest of the piers can meet the requirements. (4) the traffic safety of Qianhaizi Bridge is analyzed by increasing the earthquake intensity step by step. The results show that, first, when the peak ground acceleration PGA is 0.17g (E1 ground motion) and 0.26g (1.53E1 earthquake), the lateral displacement of the piers exceeds the limit of H / 300, but the heavy truck does not roll. Heavy goods vehicles may be capsized first, The PGA of the two combinations are 0.23g (1.35 times E1) and 0.32g (1.88% E1) respectively. The ratio of transverse displacement to height of pier is 1 / 178 and 1 / 198, respectively, which is greater than the limit stipulated in the guidelines for the Design and Construction of concrete filled Steel Tube Bridges. The value of 1 / 300 indicates that the guide limits the pier top displacement more strictly.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU398.9

【相似文献】