摘要
针对新建公路下穿已建公路桥梁时与已建桥墩发生冲突的情况,以某高速公路立交B匝道桥改建工程为背景,对已建桥墩改建为框架墩的应用进行研究。B匝道桥第五联B21号、B22号桥墩位于新规划线路上,因此将这2座桥墩改建为框架墩。采用MIDAS Civil建立该桥上部结构模型,确定框架墩横梁计算荷载,根据箱梁允许变形控制框架墩设计,框架墩采用1.5m圆形实心立柱,1.8m钻孔灌注桩基础,矩形空心横梁(支座集中力处为实心截面),墩梁刚度比取为0.18。施工中对顶升压力及顶升位移进行双控并对整体结构3次体系转换进行严格监控。对改建后的桥梁结构进行分析,分析结果表明:改建后曲梁结构受力与原结构相比未发生明显变化,振动频率改变较小,符合等效替换原则。
Given that building a road under-passing an existing roadway bridge might exert influence on the piers of the bridge, the feasibility of transforming the piers of an existing bridge to the frame-elastic piers was studied with the reconstruction project of the B ramp bridge of a highway interchange as the background. The No. B21 and B22 piers in the fifth unit of the B ramp bridge were just located on the newly planned road, therefore, the two piers were selected to be transformed to frame piers. The MIDAS Civil was used to establish the model of the super structure of the bridge to determine the calculation load for the cross beam of the frame pier. The design of the frame pier was controlled by the allowable deformation of the box girder. The pier shaft of the frame pier was the 41.5 m round solid column with the 41.8 m bored pile as its foun- dation, the cross beam was the rectangular hollow beam（the area of the bearing on which the force concentrates takes solid section）, the rigid ratio of the pier and the beam takes 0.18. During the construction, both the jacking force and jacking displacement were controlled and the three times of the system transformation of the overall structure were also strictly monitored and con- trolled. The bridge structure after reconstruction was analyzed. The results of the analysis show that the mechanical behavior of the bridge before and after the reconstruction does not have dis- tinctive change; the change of the vibration frequency is little, which conforms to the equivalent replacement principle.
出处
《世界桥梁》
北大核心
2012年第5期77-82,共6页
World Bridges
关键词
桥梁改建
框架弹性墩
结构分析
振动频率
有限元法
bridge construction
frame-elastic pier
structural analysis
vibration frequency
finite element method
