Analysis On Mechanical Performances Of Joints At Negative Moment Region Near The Middle Abutment Of Haihe Main Bridge

The Haihe main bridge had been designed as a steel-concrete composite truss bridge. The lower-chord RHS joints within the negative moment region were filled with concrete. As the steel and concrete of the joints had coordination deformation, the stress state of the bar-crossing joints was complicated. The newly designed uplift-restricted connectors were deployed between the upper chord and the concrete slab within the negative moment region. The slipping performance of the connectors was uncertain. The research contents are listed as followed.Firstly the finite model of the Haihe bridge structure was built so that the stress state and the deformation of the steel-concrete composite truss and the concrete slab at the negative moment region were investigated.Secondly the bearing capability of the concrete-filled RHS joints were investigated. The factors for the bearing capability of the joints were investigated. The results showed that the thickness of the chord was one of the major factors and the strength of the concrete would not be a major factor when the concrete strength grade was higher than C45.Thirdly the factors for the slipping performances of the uplift-restricted connector were investigated. The results showed that the classification of the foam plastics, the thickness of the foam plastics and the height of the connectors were major factors while the friction coefficient between the truss and the concrete slab was not a major factor.Fourthly two model tests were designed to verify the results.