Three-Dimensional Dynamic Response Analysis of Twin-Girder Bridge with Elastomeric Supports under Moving Vehicle Loads

在混合结构受到重视的同时，从设计、制造和施工的角度考虑桥梁体系的合理化，少梁公路桥梁成为值得关注的问题。交通荷载作用下双梁桥的板梁相对挠度可能大于顺序梁桥，因为双梁桥的板跨长于顺序梁桥。由于伸缩缝附近的相对挠度会引起交通激振引起的低频振动等问题，为此，本研究对一座双梁桥在移动车辆荷载作用下的动力响应特性进行了三维动力响应分析，不仅考虑了主梁的动力响应，还考虑了板和腹板的动力响应。在建立车桥相互作用系统模型时，采用了8自由度车辆模型和带壳单元的有限元模型来更好地表达真实桥梁，分析结果与试验结果吻合较好。结果表明，由于弹性支座在竖向的位移，车辆通过桥梁伸缩缝时，桥梁的加速度响应被放大，腹板的平面加速度响应也由于板的大跨度而被放大。此外，还确定了腹板的固有频率分布在15~27赫兹之间。

While hybrid structures are paid attention to, highway bridges with small number of girders become noteworthy from a viewpoint of rationalization of bridge system in design, fabrication and construction. Twin-girder bridge's relative deflections of slab to main girders due to traffic loads may be greater than those of ordinal girder bridges, because slab's span length of the former is longer than that of the latter. The relative deflections near expansion joints can give rise to some problems like low frequency vibration due to traffic-induced vibration.Therefore, for not only the main girder response but also the slabs and web plates behavior, a three-dimensional dynamic response analysis of a bridge is carried out to investigate the dynamic response characteristics of a twin-girder bridge under moving vehicle loads in this research.In modeling a vehicle-bridge interaction system, 8-degree-of-freedom vehicle model and FE model with shell element, which are adopted to express the real bridge more clearly, are used The analytical results of bridge agreed well with the experimental results. It becomes cleared that, since elastomeric support displaces in vertical direction, acceleration responses of the bridge are amplified, when a vehicle passes the expansion joint of the bridge.Out of plane acceleration responses of web plates are also amplified due to the slab's long span. In addition, it was confirmed that natural frequencies of web plates are distributed between 15Hz and 27Hz.