斜拉体系加固东明黄河公路大桥主梁锚固区段模型试验研究

摘要

东明黄河公路大桥是采用斜拉体系加固的大跨径预应力混凝土连续刚构桥,为研究新增索力作用下新增的钢托梁、钢托架及主梁锚固区段箱梁局部的受力性能,选取距跨中截面22.15 m长索锚固端9 m混凝土箱梁建立缩尺模型,对节段模型静力加载至2.5倍设计索力时的静力强度和挠度进行测试,分析试验模型在对称加载和偏载作用下的静力力学特征.试验结果表明:对称加载至设计索力和偏载至1.1倍设计索力时,混凝土箱梁受力性能良好,钢托梁抗弯刚度可靠,结构处于线弹性阶段,可以用线弹性理论进行分析;随着荷载的继续增大,钢托梁悬臂根部最先达到屈服应力,挠度曲线呈非线性特征,塑性变形明显;达到2.5倍设计索力时,钢托梁多点应力屈服,混凝土箱梁受力性能良好,钢托架具有足够的安全储备,钢托架锚固性能可靠,但高强度螺栓预紧力损失较大.%The Dongming Huanghe River Highway Bridge is the first long-span prestressed concrete continuous rigid-frame bridge strengthened by using the cable-stayed system.To study the load bearing capacity of the steel corbel beams and steel brackets as well as the local load bear-ing capacity of box girders in the main girder anchor zone under the action of the newly-added cable forces,the 9 m long section of concrete box girder at the cable anchoring end that is 22.15 m away from the midspan section was chosen to establish the scale-down model,to test the static intensity and deflection of the sectional model when the static load was applied to the 2.5 times of the design cable force and to analyze the static load bearing property of the experimental model under the ac-tion of symmetrically-applied loads and eccentric loads.The results of the experiment demonstrate that the load bearing performance of the concrete box girder is good and the anti-bending rigidity of the steel corbel beams is reliable,w hen the loads are symmetrically applied to the design cable forces and 1.1 times of the design cable forces.The structure is in the condition of elastic phase, which can be analyzed by the linear elastic theory.As the continuous increase of the loads,the root of the cantilevers of the steel corbel beams first reached the yield stress,the deflection curve showed signs of non-linear property and the plastic deformation was obvious.When the loads ap-plied reached 2.5 times of design cable forces,the steel corbel beams displayed multi-point stress yielding,the load bearing performance of the concrete box girder acted well,the steel brackets had enough safety margin,the anchoring performance of the steel brackets is reliable,but the pre-tightening force of the high strength bolts suffered heavy loss.