Study On The Mechanical Behavior Of Assembled Composite Beam Considering The Effect Of Cluster Degree

Supported by the Chongqing Natural Science Foundation " study on the mechanical behavior and calculation theory of double uncoupled structure of assembled composite beams "(cstc2018jcyj AX0509),this paper is to study the different cluster degrees(an index reflecting the cluster degree of the stud groups,defined as the number of studs in a single reserved hole / Number of full beam studs)on the mechanical behavior of assembled steel-concrete composite beams,a set of five-piece assembled composite beam loading tests were carried out,and a simulation method was proposed to accurately simulate the interface characteristics of assembled composite beams,Derive the mechanical equation expressions of assembled composite beams considering the the stud groups layout of assembled structure and sliding deformation characteristics.The main research work is as follows:(1)Designed a set of 5 assembled composite beams with the same degree of shear connection,only changing the cluster degree and the arrangement of studs in the holes.From the aspects of failure mode,load-displacement curve,load-slip curve and crosssection strain distribution of composite beams,the mechanical properties of composite beams under single-point loading in the span are compared and studied.(2)Combined with the ABAQUS finite element software,a finite element simulation method for assembled composite beams that precisely simulates the interface relationship between pre-and post-casting concrete interface is proposed: A zero-thickness cohesion model combined with normal hard contact was used to simulate the tension-compression heterogeneous constitutive structure of pre-and post-casting concrete interface,and the difference in connection between the contact interfaces was simulated by setting different friction coefficients between the interface of the postcast plate,precast plate and steel beam;(3)Based on the discontinuity of the stud groups layout of the assembled composite beam and the continuity of slip deformation,it is assumed that the shear force and interface slip of the steel-concrete interface have different distribution functions in the reserved holes and prefabricated sections.The slip deformation distribution equation of composite beams under concentrated and uniformly distributed loads;based on the piecewise slip boundary coordination conditions and the stiffness reduction of the stud groups effect,using MATLAB calculation software,the analytical solution of the slip deformation equations of assembled composite beams is realized;The mechanical equations of steel beams and concrete slabs considering nonlinear slip are proposed.Aiming at a 50 m span simple supported assembled composite beam under construction,the influence of shear connection degree and cluster degree on the mechanical behavior of assembled composite beams was studied based on the method in this paper.