Under the background of a reinforcement project of the long-span reinforced concrete truss arch aqueduct in active service and according to the field investigation and FEM design review of original structure, this paper put forward an external prestressing strengthening design idea, which was used to strengthen reinforced concrete tension bar and coordinated with the current specification. Then, combining with the data of static loading test in situ and ANSYS modeling analysis, this paper explored and verified the effects of the method. The results show that the method has obvious advantages and its effect is remarkable. Firstly, it can improve the bearing capacity and stiffness of the original structure in a large extent. In addition, the stress level of the original structure reduces due to the load is born by both prestressed reinforcement and original structure. Finally, the deformation of reinforcing system is coordinated and well integrated that it can effectively reduce the stress lag effect which is difficult to be resolved by other reinforcement methods.%依托某现役大跨度钢筋混凝土桁架拱渡槽加固改造工程,根据现场调查测试和原结构有限元设计复核结果提出一条与现行规范相协调的体外预应力加固钢筋混凝土桁架受拉杆件的设计思路,并结合原位静载试验数据和ANSYS有限元建模分析探究、验证体外预应力加固钢筋混凝土桁架受拉杆件的效果.研究结果表明:体外预应力加固大跨度钢筋混凝土桁架受拉构件具有较明显的优点,能够在较大程度上提高原结构的承载力和刚度.加固体系中预应力筋与原结构共同受力,降低了原结构的应力水平;加固体系变形协调一致,整体性较强,有效减小了其他加固方法较难解决的应力滞后效应,加固效果显著.
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