Study On Fire Resistance Of Steel-concrete Composite Beam Considering Slip Of Studs

Steel-concrete composite beam is more and more widely used in thecivil-engineering field because it could develop the advantages of both steel andconcrete structures, and avoid the shortcomings of them also. Steel-concrete compositebeam is a whole structural type which consists of steel beam and concrete slab by shearconnectors, which can resist the lift and relative slip on the interface of steel beam andconcrete slab. The stud is a flexible shear connector which is commonly used, manyscholars have studied about shear capacity and slip performance of studs at roomtemperature, and many specifications have carried out detailed provisions about these.However, only the Europe codes have put forward some provisions about shear capacityof studs at high temperature, while no codes put forward any provisions about slipperformance of studs at high temperature. The relative slip between steel beam andconcrete slab is related to performance of studs, the slip determines the varyperformance of composite beam. In theory, the relative slip between steel beam andconcrete slab of full shear connection composite beam could be neglected, while forpartial shear connection composite beam, we must consider the influence of slip on theperformance of composite beam. In engineering practice, if composite beam couldinsure the structural requirements, design of composite beams with partial shearconnectors could achieve good economic benefits. At present there are no relevantspecifications which consider the shear slip of studs about the fire resistance ofcomposite beams under the high temperature in fire.In this article, there are the fire resistance tests of full shear connection compositebeam and partial shear connection composite beam, and the theoretical calculation ofthe performance when composite beams under high temperature. The results oftheoretical calculation and fire test were compared, parameter analysis were carried outabout the fire resistance of composite beams with different shear connection degreesand different temperature. The main contents and conclusions are as follows：①Theoretical analysis: Introduce the research of domestic and overseas codes andscholars about shear capacity of studs and slip performance at room temperature andhigh temperature. Also, introduce the fire resistance capacity design methods ofdifferent countries, and compare with each other.②Heat transfer analysis: Analyses the heat transfer of composite beam at high temperature, calculate temperature of member, obtain the parts’ temperaturedistributions of composite beam at high temperature, and understand thecharacteristics of temperature distribution.③The material tests of steel plates、steel bars and concrete: Carry out thematerial tests of materials used to the composite beam, measure yield strength、ultimate tensile strength、 elongation of steel plates and steel bars, also the compressivestrength and elastic modulus of concrete.④Fire resistance tests of composite beams: Design two composite beams, a fullshear connection composite beam, and a partial shear connection composite beamwhich shear connection degree is0.5, carry out the fire resistance tests in the ISO834standard heating, and compare the results of them.⑤Theoretical inference: Calculate the fire resistance capacity, deflection and slipof composite beams by computer programming through the theory of capacity and slipat room temperature to which at high temperature, and compare the results with thetests’ results with good agreement.The results of the study show that shear bearing capacity of studs and slipproperties at room temperature have significant difference with which at hightemperature. The shear capacity and anti-slip capacity degrade fast at high temperature.The shear connection degree has significant effect on the fire resistance of compositebeam, when comparing with the shear connection composite beam, the partialconnection composite beams have significantly lower bearing capacity and ductility,also increase the deformation, the slip and uplift displacement. The theoreticalinference and experimental data are agreement with each other well, which can be usedas references to design the composite beam in fire considering the slip of studs.