后结合预应力组合梁桥的抗裂性能试验

Experiment on Crack Resistance Performance of Post-Connected Prestressed Composite Girder Bridge

为研究后结合预应力组合梁桥的预压应力分布和负弯矩区抗裂性能,设计2根连续组合试验梁,其中一根为负弯矩区设计成全预应力混凝土板的后结合组合梁,另一根为无预应力的普通组合梁。测试了试验梁在张拉预应力筋和静力加载过程的受力性能,得到负弯矩区截面的应力状态和裂缝分布。试验表明:因钢梁和混凝土板不连接,预压应力由混凝土板承担且混凝土截面的预压应力沿着横向的分布不均匀。后结合预应力组合梁的初始开裂荷载和群钉孔外的开裂荷载分别是普通组合梁的3.1和5.0倍。后结合预应力组合梁抑制裂缝沿着横向贯穿混凝土板,提高了负弯矩区的抗裂性能。混凝土平均裂缝间距约等于横向钢筋间距。后结合预应力组合梁在开裂后的受力状态与普通组合梁类似。

In order to study the pre-compression stress distribution and the crack resistance performance of the negative moment region of the post-connected prestressed composite girder bridge,two continuous composite test girders were designed.One was a post-connected composite girder whose concrete slab in the negative region was designed as a fully prestressed concrete slab,and the other was a normal composite girder without prestress.The mechanical behavior of the girders in the process of tensioning prestressed tendons and static loading were tested,and the stress state and crack distribution of the sections in the negative moment region were obtained.The test shows that the pre-compression stress is borne by the concrete slab because the steel girder and the concrete slab are not connected.The pre-compression stress of the concrete section is unevenly distributed along the transverse direction.The initial cracking load of the post-connected prestressed composite girder and the cracking load outside the group stud hole are 3.1 times and 5.0 times that of the normal composite girder,respectively.The post-connected prestressed composite girder suppresses cracks that penetrate the concrete slab along the transverse direction and improves the crack resistance performance in the negative moment region.The average crack spacing of concrete is approximately equal to the spacing of transverse rebars.The stress state of the post-connected prestressed composite girder after cracking is similar to that of the normal composite girder.