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

Abstract:

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.

Key words:composite girder;post-connection;prestress;negative moment;crack;experiment