PC连续箱梁桥0号块受力性能的影响参数分析

Study of Parameters Influencing Load Bearing Performance of No.0 Block in PC Continuous Box Girder Bridge

为研究PC连续箱梁桥0号块建模参数对其受力性能的影响程度,以选取合理的建模参数,以某跨度为(55+90+90+55)m的PC连续箱梁桥为工程背景,建立0号块空间有限元模型,分析不同桥墩高度、预应力筋沿程预应力损失、支座约束等参数下0号块受力性能的变化规律,以及最大悬臂施工阶段和成桥阶段0号块的空间应力特点。分析结果表明:0号块箱梁底板与支座相交位置应力受墩高影响明显,建模时应考虑桥墩的影响,墩高可按1倍梁高左右简化处理;沿程预应力损失分布对0号块受力影响明显,计算时应考虑其影响;运营使用阶段如不考虑支座约束,0号块局部应力失真,应力计算时可采用固结约束代替真实支座进行简化处理;0号块在横隔板等截面突变位置主拉应力较大,应优化构造尺寸和配筋,以及加强施工质量控制。

To study the load bearing performance of No.0 blocks in the superstructure of PC continuous box beam bridge,a PC continuous box beam bridge with span arrangement of（55＋90＋90＋55）m was taken as the study background.The spatial finite element model of the No.0 block was established to study the variation of parameters on the load bearing capacity of No.0 block,including the height of the piers,prestressing loss along the prestressing tendons and the constraints of the bearings.And the features of the spatial stress of the No.0 block during the longest cantilever construction stage and in the completed bridge state were analyzed.The results of the analysis indicate that the stress in the intersection of the bottom slab of the No.0 block box beam and the bearings is prone to the influence of pier height,therefore,the influence of piers should be taken into account during the model establishment,and pier heights can choose one time of the beam depth to simplify the process.The surrounding prestressing distribution exerts significant influence on the load bearing capacity of No.0 block.During the operation period,if the stress local distortion of the No.0 block at the bearings is not considered,the fixed constraints can be used to replace the real bearings in the stress calculation of No.0 block as a simplified treatment.At the locations where constant cross section of the diaphragm showing abrupt change,the main tensile stress in the No.0 block will exceed the values prescribed in the code.