Study On Flexural Performance Of Prefabricated Steel-concrete Composite Beams

Prefabricated steel-concrete composite beams are widely used in practical engineering due to their advantages such as quick construction,less wet work on site and precise machining of components.And,in recent years,the research on composite beams is more extensive.Nowadays,the research on flexural performance for the prefabricated composite beams,especially the stud cluster arrangement scenario is still insufficient.Aiming at the existing problems,this paper studied the flexural performance of prefabricated composite beams through experimental research and finite element analysis.The main research contents are as follows:(1)The effects of the patterns of stud arrangement and the spacing of studs on the flexural performance of composite beams are studied through carring out flextural tests on six prefabricated composite beams under positive bending moment.The test results show that,the prefabricated composite beams mainly have two failure modes: flextural failure and flextural shear failure,and longitudinal cracks along the reserved holes appeared in the concrete slab surfaces of all speicimens.The cracking resistance of composite beams becomes worse with a decrease in the shear connection degree,but when the shear connection degree is the same,the pattern of stud group arrangement can improve the cracking resistance of composite beams.When the studs are arranged in the same way,the composite beams with higher shear connection degree have higher load-bearing capacity and better ductility.And when the shear connection degree is the same,the composite beams with stud group arrangement have higher load-bearing capacity,but it has poor ductility.(2)Based on the experimental study,32 models of composite beams are established by using ANSYS finite element analysis software,and the effects of different design parameters on the flexural performance of prefabricated composite beams are analyzed.The results show that,the ultimate load-bearing capacity of composite beams increases with a decrease in the span-depth ratios,and when the studs were arranged in uniform or group type,the ultimate load-bearing capacity of composite beams with the span-depth ratios of 6.75 increases by 53.3% and 53.0%,respectively,compared with the composite beams with the span-depth ratios of 9.00.The thickness of the steel girder web can improve the ultimate load-bearing capacity of the composite beams,when the thickness of steel girder web increases from 6 mm to 14 mm,the maximum increase of the ultimate load-bearing capacity of composite beams with stud were arranged in uniform and group is 17.0% and 16.6%,respectively,but it has little effect on the ultimate deformation of composite beams.The ultimate load-bearing capacity of composite beams decreases with an increase in the stud spacing.When the stud spacing with uniform arranged pattern increases from120 mm to 300 mm,the maximum bearing capacity decreases by 11.0%,and when the stud spacing with group arranged pattern increases from 140 mm to540 mm,the maximum bearing capacity decreases by 9.4%.When the interfacial shear requirements are met and the stud group arrangement is used,the stud spacing can be appropriately increased to 500 mm,and its bearing capacity is basically the same as that of the composite beam with the uniform stud spacing of 300 mm.The ultimate load-bearing capacity of composite beams increases slightly with an increase in the strength of post-pouring concrete,but the amplitude is limited.(3)Based on the experimental study and finite element analysis,the applicability for prefabricated composite beams about the calculation methods for ultimate flexural capacity and deflection of steel-concrete composite beams in the current code and other methods is discussed,and the relevant calculation methods are modified.At the same time,the mathematical model of section bending stiffness degradation of prefabricated composite beams under the action of positive bending moment is obtained by regression analysis.The research results of this paper can provide reference and basis for the design and calculation of prefabricated steel-concrete composite beams.