全体外预应力节段梁桥使用性能足尺模型试验

Full-Scale Model Test on Service Performance of Segmental Girder Bridges with Full External Prestressing

芜湖长江公路二桥引桥首次采用全体外预应力节段预制拼装连续梁桥,为明确结构使用阶段受力性能,进行足尺模型试验研究。试验以“1跨+1/3跨”结构作为足尺模型试验梁,对跨中最大正弯矩、支点最大负弯矩及支点最大扭矩工况下主梁变形、关键截面应力及转向块等构件的受力状态进行分析。结果表明:在使用阶段跨中最大正弯矩、支点最大负弯矩及最大扭转状态下,试验梁各测试断面均未发生开裂,具有良好的抗裂性;结构的应力及变形响应与理论计算值较吻合,处于弹性工作状态且受力状态良好;墩顶横梁及转向块结构使用阶段工作性能良好。

The approach bridge of the Second Wuhu Changjiang River Highway Bridge is a continuous girder bridge,which is the first bridge project that precast girder segments are assembled with full external prestressing.A full-scale model test was conducted to examine the load bearing behavior of the structure in service period,taking a full span plus 1/3 span of the approach bridge as the prototype to build up the model.The main girder deformation,stresses in the key cross sections and the load bearing conditions of the deviators were analyzed,in the load cases of maximum midspan positive bending moment,maximum hogging moment at the supports and the maximum torsional moment at the supports.The results show that no cracks occurred in the tested cross sections of the model under the conditions of maximum midspan positive bending moment,maximum hogging moment at the supports and the maximum torsional state in the service period,proving that the girder has good cracking resistant capacity.The measured stress and deformation responses of the structure agree well with the calculated results,implying that the structure is in elastic working condition and the load bearing condition is good.The pier-top cross beams and deviators can also perform well in the service period.