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简支变连续桥梁兼具简支梁和连续梁的特点,且随着施工进展而发生体系转换,而导致其正负弯矩区的配筋形式多种多样。结合4跨40m简支变连续T梁的设计与施工,利用有限元软件建立分析模型,讨论不同配筋形式和不同的有效预应力对简支变连续梁式桥的影响,得出以下结论:对于简支变连续桥梁,应综合考虑全桥应力分布、收缩徐变导致的长期效应进行负弯矩区预应力钢束设计,合理的设计方案可以很好地限制墩顶拉应力的产生,进而避免桥面裂缝的出现,但如果出现负弯矩钢束张拉不到位的情况,墩顶接缝位置很容易出现过大的拉应力导致出现横向裂缝。
The simply supported continuous bridges have the characteristics of both simple supported beams and continuous beams, and the system transformation takes place as the construction progresses, resulting in a variety of reinforcement forms in the positive and negative moment regions. Combined with the design and construction of 4-span 40m simply-supported continuous T-beam, the finite element analysis software was used to establish the analytical model and discuss the influence of different reinforcement forms and different effective prestressing on the simply supported continuous beam bridge. The conclusions as follows: For continuous bridges, the prestressing tendons in negative moment area should be designed considering the stress distribution in the whole bridge and the long-term effect caused by shrinkage and creep. The reasonable design scheme can well limit the tensile stress in the top of the bridge, However, if there is not enough tension in the negative bending moment, the transverse seam will easily appear due to the excessive tensile stress on the top seam.