Study On Interface Friction And Mechanical Behavior Of Steel-concrete Composite Beams With High Strength Bolted Connections

The high-strength bolt shear connector can better realize the assembly of the structure,so that the structure is easy to install and disassemble,and is conducive to the recovery and reuse of materials,to achieve the "sustainable development" of the structure.Therefore,It is significance to study the mechanical properties of prefabricated steel-concrete composite beams by studying the mechanical properties of high-strength bolts in composite beams.In this paper,the anti-slip performance and damage performance of the steel-concrete connection interface in the assembled composite beam under the high-strength bolt connection are experimentally studied,and the corresponding structural measures and the mechanical properties of bolts as shear connectors in the pushout test model are analyzed through the finite element simulation.Specific work and conclusions are shown below:（1）Seven groups of slip resistance tests were carried out.Considering the effects of concrete strength,steel strength,steel surface treatment and the addition of polypropylene fiber（PP fiber）in concrete,the slip resistance of steel-concrete interface under high-strength bolt friction type connection was analyzed.Base the test,the failure mode of the specimen and the crack of the concrete were observed,and the slip resistance coefficient of the steel-concrete interface was obtained.The results show that the frictional performance between the sandblasted steel and concrete is the best,and the anti-slip performance between the interface does not decrease after the second slip.（2）The parametrized analysis of several factors affecting the pre-tension of friction high strength bolts was carried out by using the finite element analysis software ABAQUS.The results show that the size of gasket,the strength and thickness of concrete,the strength and diameter of bolts all have great effects on the pre-tensile force of bolts,but little effect on the sliding strength of specimens.Concrete strength,concrete thickness and gasket size have corresponding matching relationship,and with the increase of two of the parameters,the other parameter decreases.In addition,when the pre-loading force of 8.8-grade M16 high-strength bolt is loaded to 80 k N and the maximum local damage of concrete is below 0.614,the specimen can be subjected to simulated loading analysis.（3）The finite element analysis model of high-strength bolted shear connectors was established by using the finite element software ABAQUS,and the variation rules of anti-slip bearing capacity,initial stiffness and shear bearing capacity of bolted shear connectors were analyzed.The results show that the concrete strength and bolt diameter have great effects on the sliding strength,initial stiffness and shear strength of the specimen,which all increase with the increase of the parameters,but the concrete thickness has almost no effect on the sliding strength,initial stiffness and shear strength of the specimen,and the pre-tension of the bolt only affects the initial stiffness of the specimen.GB 50017-2017 is the best fit for the simulation results.