钢腹杆PC组合梁桥抗弯性能

为研究钢腹杆PC组合梁桥的抗弯性能，开展了钢腹杆PC组合梁模型试验，研究了钢腹杆PC组合梁混凝土顶底板应变与主梁变形等随荷载的变化规律，揭示了组合梁弯曲应变沿截面高度的分布规律，得到了组合梁的破坏模式；进行了钢腹杆PC组合梁有限元参数分析，探讨了主梁高跨比和偏载效应对钢腹杆组合梁抗弯性能的影响；提出了钢腹杆PC组合梁截面开裂弯矩、钢筋屈服弯矩和极限弯矩计算方法。研究结果表明：钢腹杆PC组合梁桥的破坏过程包括弹性阶段、开裂弹性阶段、弹塑性阶段和失效阶段。在弹性阶段和开裂弹性阶段，钢腹杆PC组合梁截面顶底板变形满足“平截面假定”。钢腹杆PC组合梁跨中截面的变形与应力随高跨比的增大而减小。对于自重较小的钢腹杆组合梁桥，偏载对组合梁变形与应力的影响较大，且变形与应力增大系数随高跨比的增大而增大。与有限元和试验结果相比，本文提出的钢腹杆PC组合梁开裂弯矩、钢筋屈服弯矩和极限弯矩的计算方法具有较高的精度。

Bending Performance of Prestressed Concrete Composite Girder Bridge with Steel Truss Webs

To study the flexural behavior of PC composite girder bridge with truss webs, the model test of PC composite girder bridge with truss webs for the flexural behavior was conducted. In order to acquire the failure mode of PC composite girder bridge with truss webs, the changed rule of the strain in the bottom and top slab, and the deflection of the girder of PC composite girder bridge with truss webs with the variation of the load was studied, meanwhile, the distribution rule of bending strain along the height of the section was revealed. The influence of height-span ratio, truss web inclination and unbalance loaded on the flexural behavior of PC composite girder bridge with truss webs was analyzed, and the calculated method for the cracking bent moment, bent moment in the stage of the rebar yield and ultimate bent moment of PC composite girder bridge with truss webs was put forward. The research result shows that the failure process of PC composite girder bridge with truss webs includes elastic stage, cracking elastic stage, elastic-plastic stage and failure stage. In the elastic stage and cracking elastic stage, the deflection of the bottom and top slab of PC composite girder bridge with truss webs met the plane-section assumption. The deflection and stress in the mid-span section of PC composite girder bridge with truss webs decreases with the increase of height-span ratio. Since the PC composite girder bridge with truss webs had lesser dead load, the unbalance loaded had a significant influenced on the deflection and stress of the composite girder, and the magnification factors of the deflection and stress increase with the increase of height-span ratio. Compared with the results of finite element analysis and test, the calculation methods of cracking moment, reinforcement yield moment and ultimate moment of PC composite beams with steel truss web presented in this paper have high accuracy.