连续梁桥基于位移的抗震设计

在强震作用下,结构的位移比力更能直接反映结构的破坏状态。因此近年来,基于位移的抗震设计方法受到越来越多的重视与发展。该设计方法要求把多自由度结构转换为等效的单自由度模型(包括等效的刚度、等效阻尼及等效延性等)才能进行抗震设计。本文以连续梁桥为例,基于所建议的位移形状函数,推导了位移形状函数与桥梁跨度及刚度(墩高)的关系;在此基础上,提出了多自由度连续梁桥的等效单自由度模型,并以对称和不对称的连续梁桥为例,分别给出了基于位移的抗震设计步骤。由于设计步骤中考虑了塑性铰的屈服机制,可以看出对此两种结构其设计步骤本质上是相同的,且不需要迭代。

Displacement - Based Seismic Design of Continuous Girder Bridge

The damage state of a structure under the excitationof strong earthquake can be directly reflected through its displacement rather than force. A a result, the method of displacement-based seismic design is greatly stressed and developed in recent years. This method requires that the MODF structure to be converted to an equivalent SDOF model (including equivalent stiffness, equivalent damping and equivalent ductility etc. ), so that the seismic design can be carried out. A continuous girder bridge is taken as an example in this paper. Based on the proposed displacement shape function, the correlation between the displacement shape function and the span of the bridge and also the stiffness (pier height) is derived. Furthermore, the equivalent SDOF model for the MDOF continuous girder bridge is presented. Thereater, the procedures of the displacement-based seismic design are demonstrated by taking both symmetrical and non - symmetrical continuous girder bridges as examples. Since the yielding mechanism of plastic hinge is considered, the design procedures for symmetrical and non-symmetrical bridges are essentially the same, and no iteration is required.