Dynamic Evaluations of Safety of Secondary Structures of Bridge Structures

桥梁附属结构对行车安全起着重要的作用。在桥梁二级结构的设计中，必须考虑桥梁的振动作为二级结构的设计荷载。评估桥梁在时变交通荷载作用下的动力响应，对于辅助结构的有效设计具有重要意义。采用三维有限元模型，结合实测数据对公路桥梁的振动响应进行了评估，并对二级结构进行了应力评估。此外，还研究了采用链式阻尼器和散粒材料阻尼器等组合的减振方法。分析和测试的结果总结如下。(1)利用桥梁在交通荷载作用下的振动实测数据进行反褶积分析，以评估桥梁结构在交通荷载作用下的振动及其引起的次结构动力响应特性。结果表明，这种分析方法可以对桥梁结构的振动进行足够准确的评估。(2)结果表明，用解析法确定二级结构的设计荷载输入和计算二级结构的应力是可行的。这些结果导致疲劳安全评估。因此，在没有交通荷载实测数据的情况下，可以适当地进行桥梁次结构动力响应特性的评估。(3)结果表明，链阻尼器和散粒体阻尼器联合使用，可以有效地实现对二级结构的振动控制。在2-10 Hz的宽频率范围内，减振效果很好，而在2-6 Hz的频率范围内，弹簧质量和阻尼器与颗粒材料的组合减振效果也很好。

Secondary structure on bridges play an important role on traffic safety. In order to design secondary structure on bridge, the vibration of the bridge should be taken into account as a design loading for the secondary structures. It is important for the available design of the secondary structure to assess the dynamic response of the bridge due to time varying traffic loading. The 3-dimensional FEM model was used to evaluate the vibration response of highway bridge with survey data and was carried out the stress evaluation occurred on a secondary structure. Moreover, the vibration controlling method was examined with the method of using together chain damper and damper with granular materials etc..The results of analyses and tests are summarized as follows.(1) The deconvolutional analysis by using the vibration measurement of bridge by traffic load was carried out to assess the bridge structure vibration due to traffic, and the consequent dynamic response characteristics of secondary structure. It is demonstrated that the bridge structure vibration can be evaluated with sufficient accuracy by this analysis.(2) It is shown that it is possible to determine the design-input of load for secondary structure and calculate the stress occurred at secondary structure analytically. These results lead to fatigue safety evaluation. Therefore, the evaluation of dynamic response characteristics of secondary structures on bridge can be appropriately carried out without survey data based on traffic load.(3) It is shown that the vibration controlling method of secondary structures can be effectively carried out using together chain damper and damper with granular materials. The vibration reduction effect is very effective at wide range frequency with about 2-10 Hz.Moreover, the vibration control using together spring-mass and damper with granular materials also is effective at range frequency with about 2-6 Hz.