预制节段拼装箱梁长期变形性能研究

Long-term deformation behavior of precast segmental box girder

采用混凝土徐变理论,在整体浇筑桥梁长期变形计算模型的基础上,结合混凝土龄期效应的分时步计算法,推导出预制节段拼装箱梁的长期变形计算模型。此模型考虑了预应力损失引起的滞后弹性变形,在时间划分的足够细的情况下计算准精度较高。最后,以南沙大桥引桥62.5m跨为工程背景,利用有限元软件Midas Civil,分析了混凝土收缩徐变对南沙大桥引桥长期变形性能的影响。结果表明,所建模型可为预制阶段拼装箱梁长期性能的数值分析提供了一定的理论依据。

Based on the concrete creep theory and the long-term deformation formula of integrally poured bridges,this paper deduces the long-term deformation formula of precast segmental assembled box girders by combining the time-sharing step calculation method considering the age effect of concrete.This formula takes into account the hysteretic elastic deformation caused by the loss of prestressing force,and has high accuracy when the time division is sufficiently fine.Finally,taking the 62.5m span of approach bridge of Nansha Bridge as the engineering background and using the finite element software Midas Civil,the influence of concrete shrinkage and creep on the long-term deformation performance of approach bridge of Nansha Bridge is analyzed.The results show that the formulas presented in this paper can provide a numerical analysis for the long-term performance of assembled box girders in prefabrication stage,and certain theoretical basis is provided.