预应力损失对水平底板索连续刚构桥施工阶段力学性能影响分析

Analysis of the Influence of Prestress Loss on the Mechanical Performance of Continuous Rigid Frame Bridge with Horizontal Bottom Slab Cables during Construction Stage

摘要: 以桐梓至新蒲高速公路某水平底板索连续刚构桥为依托，建立MIDAS/Civil有限元模型，通过控制预应力张拉值和加载龄期，研究了预应力损失对水平底板索连续刚构桥施工阶段力学性能的影响。研究发现，预应力损失会导致施工阶段水平底板索连续刚构桥不同截面处下挠增大和压应力减小，但桥梁全截面仍保持受压。并且，在桥梁中跨合龙阶段，混凝土弹性压缩会使跨中钢束预应力增大，而混凝土收缩徐变和钢筋松弛会使跨中钢束预应力减小。此外，对于水平底板索连续刚构桥跨中预应力钢束，随着加载龄期的增大，预应力总损失值也会减小。

Abstract: Based on a continuous rigid frame bridge with horizontal bottom slab cables on the Tongzi to Xinpu Expressway, a finite element model was established using MIDAS/Civil software. By controlling the prestress tension value and loading age, the influence of prestress loss on the mechanical performance of the continuous rigid frame bridge with horizontal bottom slab cables during the construction stage was studied. The study found that prestress loss can lead to an increase in deflection and a decrease in compressive stress at different sections of the bridge during the construction stage, but the entire cross-section of the bridge remains under compression. Furthermore, during the mid-span closure stage of the bridge, the elastic compression of concrete will increase the prestress in the mid-span steel tendons, while the shrinkage and creep of concrete and relaxation of steel will decrease the prestress in the mid-span steel tendons. In addition, for the mid-span prestressed steel tendons of the continuous rigid frame bridge with horizontal bottom slab cables, the total prestress loss value will also decrease as the loading age increases.