| Assembled steel-concrete composite beam(ASCCB)has some characteristics,including improve the quality of construction,reduce the progress of construction and reduce the influence for the surrounding environment.At present,the research and application forcused on the cast-in-place(CIP)steel-concrete composite beam with shear stud connector.The research on the steel-concrete composite beam with rigid shear connector and ASCCB are limit,and lack of systematics.So,in this thesis,the mechanical performances of ASCCBs experimental research,finite element model(FEM)calculation and theoretical analysis have been carried out for the mechanical behavior of ASCCB,and the calculation methods of the shear capacity and stiffness of the shear stud and square steel shear connectors are also analyzed.The main contents are as follows:(1)Taking the shape of reserved hole,processing technology,loading system and type of shear connectors as control parameters,it includes 8 static loading of the shear stud group connectors(SSGCs),8 repeated loading of the SSGCs,5 static loading of the steel block shear connectors(SBSCs)and 5 repeated loading of the SBSCs.The failure mode,shear bearing capacity,shear stiffness,ductility and interface shear-slip relation curves of the push-out specimens with shear connectors are obtained.The test results showed that the SSGCs in the square reserved hole has better shear performance;The shear behavior of the shear connector in PC concrete slab is not different from that in CIP concrete slab;Both the shear connectors of shear stud group and SBSC under repeated load have good ductility;The shear stud and the root weld of the shear stud are damaged,and the square steel shear connector was damaged under local pressure of concrete.(2)2 simply-supported steel-concrete composite beams with CIP concrete slab and8 simply-supported ASCCBs were carried out respectively.The shape of the reserved hole,the width of the concrete slab,the type of shear connector,the degree of shear connection and the processing technology were selected as the parameters,the failure mode,bending capacity,deflection and relative slippage of the specimen were analyzed,and the load-deflection curves,the distribution of longitudinal strain along section height,longitudinal and transverse distribution of longitudinal strain of concrete slab and reinforcement,and the interface shear-slip curves of steel-concrete composite beams were obtained.The test results show that,the shape of the reserved hole has little influence on the bending capacity of composite beams,but the stiffness of the composite beam with funnel shape reserved hole was higher;The bending capacity and stiffness of composite beams with the width of 1200 mm and 1600 mm concrete slabs are almost the same,indicating that their effective width is less than or equal to 1200mm;The bending capacity and stiffness of composite beam with SBSCs were obviously higher than that of composite beam with SSGCs;The shear failure of shear connector occurred in partial shear connection composite beam with SSGCs,and the shear capacity and stiffness are obviously lower than that of the composite beams with complete shear connection;The bending failure of composite beam occurred in partial shear connection composite beam with SBSCs indicates that the composite beams with SBSCs can adopt larger spacing.The assembled steel-concrete composite beams can achieve the overall mechanical properties of PC concrete slab and steel beam.(3)Based on ABAQUS software,the refined FEM of the push-out test with SSGC was established.The failure phenomenon and interface shear-slip curves obtained by the FEM are compared with the experiment,and the finite element analysis results were in good agreement with the test results.The FEM verified by experiments was used for parametric analysis,and the concrete strength,diameter of the studs,height of the studs,longitudinal and transverse spacing between shear studs,strength of grouting material and the number of studs were changed respectively.Based on winkler foundation model and the comprehensive stiffness principle of the thrust pile,the theoretical calculation formula of stiffness of the shear stud was obtained.By fitting the results of finite element parameter analysis,the calculation formula of stiffness of the SSGCs considering the concrete material,stud material and diameter,and the number of shear studs in a group was obtained,and the validity of the formula is verified by the experimental results.(4)Based on ABAQUS software,the refined FEM for the push-out test of SBSCs was established.The failure phenomenon and interface shear-slip curves obtained by the FEM are compared with the experiment,and the finite element analysis results were in good agreement with the test results.The FEM verified by experiments was used for parametric analysis,and the grouting material strength,strength of concrete slab,size of the SBSCs,and longitudinal and horizontal reinforcement in the concrete slab were changed respectively.Based on the local pressure flow model and the tensile-compressive bar model,the shear capacity calculation formula of SBSCs was obtained which has high calculation accuracy.(5)Based on ABAQUS software,the refined FEM for the ASCCB under positive and negative bending moment was established,and the model of the negative bending moment considered the action of the prestressing tendons.The simulation results obtained by the FEM are compared with the experiment,and the finite element analysis results were in good agreement with the test results.The FEM is used to analyze the distribution of effective width coefficient of concrete slab along the direction of span and the variation with load class under the positive and negative bending moment,and the simplified calculation formula of effective width coefficient of concrete slab in the middle span was obtained,which is beneficial to engineering application. |
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