中文摘要：

溪洛渡±800千伏特高压直流输电工程建设过程中，需要通过公路运输大件设备，这些设备的重量已超过途经桥梁的极限承载力，需要进行临时加固。基于此，介绍了一种重载作用下的桥梁加固技术——索一桁架加固结构体系，该体系主要由预应力钢绞线和桁架组成，通过张拉钢绞线使桁架产生顶升力以抵消桥梁板自重，达到加固桥梁的目的。为了验证该体系的合理性以及加固效果，进行了足尺试验研究，模拟了重型车辆通过一跨桥梁的整个过程，考察了桥梁板加固前后结构响应的变化，研究了钢绞线穿过多个滑轮组后的预应力损失。试验结果表明，采用索一桁架加固结构体系可以部分抵消桥梁板自重，改善桥梁板内力分布，有效提升结构承载力和刚度，桥梁板在加固后以及加载时上下表面均未发生开裂；滑轮组作为转向装置可以有效传递钢绞线内力，穿过多个滑轮组后钢绞线内力损失不大。

英文摘要：

During the construction of Xiluodu ＋ 800kV ultra-high voltage direct current （UHVDC） transmission project, some heavy equipments need to be transported through highways. The weights of the equipments exceed the uhimate load-bearing capacity of the passing bridges, so it is necessary to reinforce these bridges temporarily. A cable-truss reinforced structure system composed of prestressed strands and truss is proposed. The dead-weight of bridge plates can be balanced by the lift forces the truss due to tensioning of strands. In order to verify the reasonability and reinforcement effect of the system, a full-scale test was conducted. The whole process of heavy vehicles passing the bridges was simulated, the responses before and after the reinforcement were analyzed, and the prestressing loss of strands after crossing pulleys were studied. The analysis results indicate that the cable-truss reinforced structure system can partly offset the dead-weight of bridge plates, optimize the internal force distribution and effectively increase the strength and stiffness. During the experiments, no cracks emerge in the top and bottom surfaces of the bridges after reinforcement and loading. As steering gears, the pulleys can effectively promote the internal force transmission of strands and reduce prestress loss of strands.