竖向温度梯度对箱梁受力的影响

为验证客运专线时速250 km的32 m简支箱梁的使用性能,选择4孔梁进行现场预制和试验。在梁体预制过程中顶板底面中心产生了顺桥向裂缝,裂缝在白天、夜晚呈现明显张合趋势。为分析竖向温度梯度对裂缝的影响开展了试验及理论研究。研究结果表明:存梁期间日照引起的竖向正温度梯度是桥面板裂缝产生的主要原因;裂缝主要影响结构的使用耐久性,对受力影响较小。建议有砟箱梁设计时充分考虑轨道铺设前竖向温度梯度的影响。

Influence of Vertical Temperature Gradient on Mechanical Behavior of Box Girder

In order to verify the service performance of 32 m simply supported box girder with 250 km/h speed on passenger dedicated railway four girders were selected for field prefabrication and test.In the process of girder prefabrication the cracks along the bridge were formed in the center of the roof bottom and the cracks showed obvious tension tendency in daytime and night.In order to analyze the effect of vertical temperature gradient on cracks experiments and theoretical studies were carried out.The results show that the vertical positive temperature gradient caused by sunshine during girder storage is the main cause of bridge deck cracks and the cracks mainly affect the durability of the structure but have little effect on the force.It is suggested that the effect of vertical temperature gradient before track laying should be fully considered in the design of ballasted box girder.