斜拉索体系加固箱梁桥节段局部受力性能分析

Local Mechanical Characteristic Analysis of Box Girder Bridge Segment Strengthened by Stay Cable System

为考察斜拉索体系加固箱梁桥在索力作用下箱梁的局部受力状态及托架锚固性能,首先采用缩尺模型试验研究托梁和托架在自重、偏载及设计索力作用下的锚固性能及高强螺栓的预紧力损失,然后利用有限单元法分析2. 5倍设计索力值下斜拉索体系的受力及锚固性能,最后通过实例验证斜拉索加固体系安全、可靠。研究结果表明,吊装阶段,高强螺栓预紧力初期损失较大,预紧力损失在2%～10%,后期逐渐趋于稳定,实桥托梁两端增加36. 7kN内的竖向荷载不会影响加固体系的锚固性能;张拉阶段,高强螺栓预紧力损失在1%范围内,托梁、托架及混凝土箱梁底板受力可靠、锚固连接安全。

In order to investigate the local stress state of box girder and the anchorage performance of base plates of box girder bridge strengthened by stay cable system under the effect of new cable force,firstly,a scale model test is conduced to investigate the preload loss of high strength bolts and the anchorage performance of the trimmer beams and base plates under the action of dead weight,unbalanced load and design cable force;Then the finite element method is used to analyze the mechanical behavior and anchorage performance of stay cable system under the effect of 250%design cable force;At last,the stay cable reinforcement system is verified to be safe and reliable by the living example.Test results show that in the hoisting construction stage,the preload loss of high strength bolts is higher in the early stage,accounts for 2%~10%of the pre-tightening force,and tends to be stable latterly,the anchoring performance of the reinforcement system will not be affected by the addition of vertical loads which are less than 36.7 kN on the both ends of trimmer beams.In the tension stage,the preload loss of high strength bolts is less than 1%,the mechanical behavior of the trimmer beams,base plates and concrete box girder floor are reliable and the anchoring connection of them is safe.