Study On Coupling Of Interface Nonlinear And Creep Of Simply-supported Steel-concrete Composite Beams

Steel concrete composite beam is made up of three parts:concrete slab,steel beam and shear connector,which makes full use of the tensile properties of steel and compressive properties of concrete.The creep behavior of concrete and the nonlinear behavior of the interface have great influence on the long-term behavior of composite beams,and the coupling between them is very important.At present,there are few researches on the coupling between the interface nonlinear and creep of concrete,so it is necessary to study it further.In this paper,on the basis of the existing experiments,the numerical simulation of steel-concrete composite beams is carried out,and the influence of the nonlinear and creep coupling on the long-term behavior of composite beams is studied.The main work is as follows:1.The current situation of the study on the coupling of nonlinear and creep of steel-concrete composite beams are summarized;2.The basic theory,calculation method and existing prediction model about the creep of the composite beam are studied;3.The nonlinear analysis method and interface nonlinear model of composite beams are studied;4.Using the subroutine interface(User subroutine Creep)provided by the finite element software abaqus,the creep subroutine is compiled;Four methods of curve fitting method,effective modulus method,CEB-FIP90 prediction model and ACI209 prediction model are used to simulate the existing steel-concrete composite beams;5.A method to modify the interface stiffness with time is proposed.The calculated results are in good agreement with the experimental results;6.Parameter sensitivity analysis of three parameters of concrete strength,interface connection and concrete age is done.