整体式弯桥试设计研究

Trial-design Study on Integral Curved Bridge

以某实桥为工程背景,进行整体式弯桥的试设计和设计验算。采用MIDAS/Civil2015有限元软件分别建立了原桥和整体式弯桥的3D有限元模型,后者考虑了台-土及桩-土相互作用。对比分析了两者在恒载、活载(汽车荷载)、温度荷载、混凝土收缩以及地震等荷载作用下的受力性能。结果表明:由于梁端固接和台后土压力等影响,恒载、活载、温度及混凝土收缩等荷载作用下,整体式弯桥梁端具有较大的负弯矩;整体式弯桥在恒载作用下的主梁弯矩值较原桥均匀,而在活载作用下主梁弯矩值与原桥相近;温度荷载对整体式弯桥的主梁内力影响最大,其次为混凝土收缩效应,在设计中应引起重视;在恒载、活载作用下,整体式弯桥和原桥的主梁扭矩基本呈反对称分布,且恒载下的主梁边跨扭矩显著小于原桥,而在活载下两者的主梁扭矩相差不大,整体式弯桥表现出较优的抗扭性能;此外,整体式弯桥的抗震性能明显优于原桥,可有效避免主梁在地震中的侧向偏位和落梁等现象,在高震区使用更具优势。

Based on a practical bridge,the trial design and design checking of integral curved bridge were carried on.The 3D finite element model of the original bridge and the trial-design bridge were built respectively by using MIDAS/Civil2015 software,and the latter one considered the pile-soil interaction and abutment-soil interaction.Then the mechanical performances of original bridge and integral curved bridge were analyzed and compared under dead load,live load(vehicle load),temperature load,concrete shrinkage and seismic load.The results show that the girder end has greater negative bending moments under dead load,live load,temperature load,concrete shrinkage and seismic load because of a fixed connection at the girder end and earth pressures behind abutment.Compared with the original bridge,the girder of the integral curved bridge has a relatively uniform bending moment distribution under dead load,but the effect of live load on bending moments of the girder is similar.The temperature load has a greatest influence on internal forces of girder of the integral curved bridge,and the second is concrete shrinkage,so they should be taken seriously in design.The torques of the girder of the original bridge and integral curved bridge are basically antisymmetric under dead load and live load,and the torques of girder on the end spans of the integral curved bridge are significantly smaller than the ones of the original bridge under dead load,but the torques of girder between the two are not much different under live load,so it can be known that the trial-design curved bridge has a better torsion performance than the original bridge.Besides,the seismic performance of the integral curved bridge is rather better than that of the original bridge,and it can effectively avoid the lateral movement and falling of the girder during earthquake action,so the integral curved bridge can be applied preferably in high seismic zones.