反复荷载作用下的预应力混凝土梁变形

为了分析反复荷载对预应力混凝土梁变形性能的影响，对6片预应力混凝土模型梁进行了低频反复加载试验，在模拟实桥活载效应的荷载作用下，研究了不同预应力度的预应力混凝土梁变形性能和钢束有效预应力变化特征。结果表明，在反复荷载作用下，预应力混凝土模型梁残余挠度和荷载挠度（弹性挠度）较常量荷载下的对应值均有所增大，其中荷载挠度增大系数为1.05~1.10；反复荷载作用对预应力筋长期损失有较明显的影响，且预应力梁的残余挠度与预应力钢筋的残余变形有着密切关系。

Deformation of prestressed concrete beam under repeated loads

To study the influence of repeated loads on the deformation of prestressed beam, low frequency repeated loads experiments of six PC T girders were conducted, and the deformation characteristic and the effective prestress of the strands of the model beam investigated under the test loads which simulated the effect of the service load. The test results show that the residual deflection and the elastic deflection of the beam increase under 2 million repeated loads compared with that under the constant load. The amplification coefficient of the elastic deflection approximately lies between 1.05 and 1.10. Furthermore, the repeated loads has obvious influence on the long term prestress loss of the strands, and the residual deflection of the PC girders has close relationship with the residual extension of the strands.