大跨预应力混凝土箱梁桥施工期腹板开裂研究

为探求一座大跨预应力混凝土箱梁桥施工早期腹板开裂原因,在实桥上进行了水化热测试.基于施工现场同条件养护混凝土早龄期力学性能发展规律的实测结果,应用有限元方法按照实际施工过程建立时变模型,对箱梁混凝土水化热所致的温度场和应力场进行分析,并对预应力张拉进行了模拟.结果表明:水化热计算结果与实测值吻合良好,过高的水化热是引起该桥箱梁腹板早期开裂的主要原因之一,而预应力张拉时结构应力处于较低的水平.

Study on Early Crack in the Web of Long-span PC Box Girder Bridge

The hydration heat was tested to investigate the early crack in the web of a long-span PC box girder bridge.Based on the mechanical properties of specimens cured at the construction site,the temperature and stress fields were simulated in time varying model by finite element method.The prestress tension was analyzed with construction stage considered as well.The results demonstrated that the calculated results of hydration heat agreed well with the measured ones.The hydration heat is one of the main reasons for the early cracks in the web of box girder,while the stress of the concrete box girder is at a very low level during prestress tension.