Fracture simulation of a demountable steel-concrete bolted connector in push-out tests

Many bolted connectors were proposed for use in steel-concrete composite structures over the past few decades. This is because using bolted connectors could make the assembly and disassembly of steel-concrete composite structures more convenient and reusing the dismantled structural components could also improve structural sustainability. Lots of static and fatigue experimental tests on steel-concrete bolted connectors were conducted but detailed finite element simulations including fracture of bolted connectors were rarely reported. This paper presents a series of simulations of a demountable steel-concrete bolted connector in push-out tests, which was proposed and reported by the authors of this paper before. Damage models of bolt and concrete materials are incorporated in the simulations to better understand the behaviour of the bolted connector and the failure mode of the push-out tests. Direct tension tests on bolts are simulated to calibrate the stress-strain relationship of bolt material and assumed pure shear tests on bolts are modelled to validate the fracture criterion used in the simulations. Results of modelling push-out tests indicate that the friction force at the steel-concrete interface accounts for a part of shear resistance of the bolted connector in push-out tests conducted. The load-slip curves and the fracture of bolts in push-out tests can be approximately predicted by incorporating damage models of bolt and concrete materials and considering an appropriate friction coefficient. The effects of concrete damage model, clearance in bolt hole, and pretension of short bolt on the shear performance of the bolted connector are discussed at last.