预制RPC柱降低大跨PC刚构桥跨中长期下挠分析

为解决大跨PC刚构桥跨中长期过度下挠的问题,提出了在刚构桥负弯矩区箱梁底板、跨中顶板加入预制RPC(活性粉末混凝土)柱形成局部RPC-NC(普通混凝土)复合截面的方法.对RPC-NC复合截面柱进行有限元分析,探讨了RPC对减小复合截面柱收缩徐变效应的作用以及RPC与NC间应力重分布规律,同时分析了剪力键受力性能.提出预制RPC柱应用于实桥的设计方案,并通过有限元对比分析加入预制RPC柱对全桥应力、跨中下挠等的影响.结果表明,加入预制RPC柱能明显降低负弯矩区结构转角和RPC附近NC的压应力,使结构成桥后的跨中长期下挠减小53.9%.

Analysis of Precast RPC Column on Reducing Long-term Mid-span Deflection of Rigid Frame Bridge

To reduce long-term and excessive mid-span deflections of long-span PC rigid frame bridges, a method of adding precast RPC (reactive powder concrete) columns into the bottom plate of the negative moment region and the mid-span roof of the rigid frame bridge to form RPC-NC (Normal Concrete) composite section was proposed. The RPC-NC composite column was analyzed to investigate the influence of RPC on reducing creep and shrinkage effects of the composite column and the stress redistribution between RPC and NC as well as the mechanical capability of shear bond. Based on the above research, design scheme of prefabricated RPC column used in actual bridge was put forward, and then the influence of the precast RPC column on the whole bridge stress and the mid-span deflection was analyzed by finite element method. The results demonstrate that the added precast RPC obviously reduces the rotation of the negative moment region and the compression stress of NC near RPC, which decreases the long-term mid-span deflection after the construction of the rigid frame bridge by 53.9%.