轻质砼在大跨度PC桥梁加固中的应用

The Application on Light-weight Aggregate Concrete Applied to the Strengthening of Long-span PC Bridge

以某大交通、重交通高速公路一座严重下挠和开裂的(65+100+65 m)PC连续梁桥为加固工程实例,介绍了桥面铺装采用LC40轻质砼减载和箱梁内增设体外预应力相结合的主动加固方案。分析了轻质砼的加固效果和优越性;阐述了轻质砼配合比设计,主要力学性能指标,施工工艺,质量改善的具体措施。采用轻质砼能大大减少体外预应力束的用量,减少了结构恒载效应,增加了结构承载汽车活载的能力,提高了桥梁结构加固效率。

Based on an existing pre-stressed concrete girder bridge with the span of 65＋100＋65m,and with severe deflection and cracks under a certain big traffic 、heavy traffic load expressway,reducing load of pavement method by use of light-weight aggregate plus adding external pre-stressing tendons plus is the recommended retrofitting strategy.The strengthening effect on light-weight aggregate concrete is analyzed.The design of mixture ratio、construction workmanship and traffic organization of light-weight aggregate concrete are set forth.Several measures of improving the quality of light-weight aggregate concrete are introduced.By use of light-weight aggregate concrete,it can minimize the quantities of external pre-stressing tendons,reduce the effect of structural dead,enhance the bearing capacity of live vehicle load,and improve the strengthening efficiency of bridge structure.