Dynamic Evaluations of Safety of Secondary Structures of Bridge Structures

桥梁上的二次结构对行车安全起着重要作用。在桥梁上进行二次结构设计时，应考虑桥梁的振动作为二次结构的设计荷载。评估桥梁在时变交通荷载作用下的动力响应对二次结构的合理设计具有重要意义。利用三维有限元模型，利用实测数据对公路桥梁的振动响应进行了评估，并对某二次结构进行了应力评估。在此基础上，采用链式阻尼器、颗粒材料阻尼器等方法对桥梁结构的振动控制方法进行了研究，分析和试验结果如下：(1)利用交通荷载作用下桥梁的振动测量进行了反卷积分析，评估了桥梁结构在交通荷载作用下的振动，以及由此产生的二次结构的动力响应特性。结果表明，该分析方法能够较准确地评价桥梁结构的振动。(2)分析结果表明，可以确定二次结构的荷载设计输入，并对二次结构产生的应力进行解析计算。这些结果为疲劳安全性评估提供了依据。因此，在没有基于交通荷载的调查数据的情况下，可以适当地对桥梁上二次结构的动力响应特性进行评估。(3)研究表明，链式阻尼器和颗粒材料阻尼器共同使用可以有效地进行二次结构的减振控制。在2~10赫兹的宽频范围内，减振效果很好；在2~6赫兹的频率范围内，弹簧质量和颗粒材料阻尼器的联合减振效果也很好。

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.