Experimental study on residual mechanical properties after cyclic loading of steel-concrete composite-laminated beams

The cracking of concrete flanges in the negative bending moment region has always constrained the development of steel-concrete composite continuous beams. The proposal of steel-concrete composite-laminated beam is one of the effective ways to solve this problem. As a new type of structure, the research on its mechanical properties is not yet sufficient. In order to study the residual mechanical properties of composite-laminated beams after cyclic load tests, static load tests were conducted on one composite-laminated beam specimen, and cyclic load and final failure static load tests were conducted on three composite-laminated beam specimens. The experimental results show that the fatigue failure mode of the composite-laminated beam was characterized by uplift-restricted and slip-permitted connectors failure, and the steel beam was still in an elastic state at this time. Compared with the static load specimen, the stiffness of the specimen that failed in the cyclic loading test decreased by about 30%, the bearing capacity decreased by about 10%, and the residual bearing capacity and ductility were basically stable, without affecting the normal operation of the specimen. Therefore, the new structure not only has good static performance, but also has good fatigue resistance.