Study On Mechanical Behavior And Hogging Moment Zone Cracking Of Steel-Concrete Continuous Composite Beams

Steel concrete composite beam is a new beam structure developed on the basis of reinforced concrete beam and steel beam.Although the steel-concrete composite beams have been widely studied at home and abroad,and the corresponding design theory and calculation methods are put forward.Because the stress of steel concrete continuous composite beam is more complex and the influence factors are too many,so it is necessary to analyze the loading capacity,deflection,slip,especially the negative bending moment.Firstly,the continuous steel-concrete composite beam is the basic theoretical analysis,including the analysis of the slip and deformation of the composite beam,positive bending moment and negative bending under the plastic limit analysis and deflection calculation analysis,calculation and analysis of the negative bending cracking load,calculation of maximum crack width for negative moment.Then,the finite element method and ANSYS software are used to analyze the steel-concrete composite continuous beam.Simulation of the reinforced concrete wing plate with Solid65 unit;simulation of steel beam with Shell43 unit;simulation of stud connectors with Combine39 unit.The ultimate flexural capacity of steel-concrete continuous composite beams is calculated.The accuracy of the model is verified by comparing the calculated values with the theoretical values.The formula for calculating the deflection formula of elastic stage is proposed,by comparing the standard values and the finite element calculation results,verify the rationality of the formula.and computing more advantages in the calculation of partial shear connection degree of deflection of composite beams in elastic stage.Finally,with the help of ANSYS software on the basis of the finite element model of the shear connection degree of different positive and negative bending moment,the different concrete strength grade and the transverse reinforcement ratio of concrete wing plate are calculated and analyzed,obtained their influences on steel-concrete composite continuous beam deflection,loading capacity,slip and negative bending cracking load.The deflection and sliding value of the continuous composite beam decrease with the increase of the shear connection degree of the composite beam,the ultimate loading capacity increases with the increase of shear connection degree,especially the shear connection degree of the negative bending moment is more significant.With the increase of the concrete strength grade,the deflection and slip of the continuous composite beam decrease,Ultimate loading capacity and the negative moment cracking load increases.However,when the strength of concrete exceeds a certain value,the influence is getting smaller and smaller.The transverse reinforcement ratio of concrete wing plate has a great influence on the loading capacity deflection and negative moment cracking load of continuous composite beams.When the transverse reinforcement ratio of concrete wing plate is more than 0.8%,the influence is smaller and smaller.