特大跨连续刚构箱梁底板防崩性能分析

Analysis on Prevention of Bottom Slab Collapse of Large-span Continuous Rigid Frame Box Girder

对预应力混凝土连续刚构桥合龙束张拉底板预应力筋时易发生的底板崩裂和裂缝现象进行分析,了解底板的受力特性,推导出曲线预应力束的等效荷载;对预应力径向力对底板混凝土的作用进行分析,提出了预应力束最小曲率、合龙段高程差限值及曲线预应力束的定位误差限值,计算了背景桥梁底板的抗裂设计参数,可为同类桥型的底板抗崩裂设计提供一定的参考。

The phenomenon of bottom slab collapsing and cracking that might occur while stretching prestressed tendon for the closure bundle of concrete continuous rigid frame bridge was analyzed to get to know the mechanical properties of the bottom slab, and the equivalent load of curve prestressed steel beam was deduced. The impact of radial force of prestress on the bottom slab was analyzed, and the minimum curvature of the prestressed beam, limitation of difference of elevation of the closure segment and limitation of location difference of curve prestressed steel beam were presented. Parameters for anti-crack design were calculated, which provides reference for similar bridges.