Residual mechanical properties of composite beams with PBL connectors under fatigue loads

Abstract

Experimental and theoretical calculation approaches were used to explore the residual mechanical properties of steel–concrete composite beams with Perfobond rib shear (PBL) connectors after fatigue loading. Six test beams were designed and fabricated including four PBL connector beams and two stud shear connector beams. The static performance, fatigue life, and failure mode under static and fatigue action were compared among the beam samples. The fatigue properties and residual mechanical properties of the beams with PBL connectors were then investigated under different fatigue load amplitudes. A calculation model for the post-fatigue residual bearing capacity of the PBL connector beam was established based on the test results and the theory of material residual strength. Compared with the stud composite beam, the PBL connector composite beam shows better static strength and fatigue resistance under the same loading conditions. The fatigue load amplitude has a greater impact on the fatigue performance of the PBL connector composite beam than the stud composite beam; when the fatigue load amplitude is 28% of the ultimate bearing capacity, the fatigue life of the composite beam is only 1.2 million loading times. The proposed calculation model of residual bearing capacity of composite beams with PBL connector yields results in accordance with experimental values, indicating that it has strong applicability. The results presented here may provide a workable reference for improving the design of steel–concrete composite beams with PBL shear connectors.