Study On The Interface Slip Of New Type Of T-section Steel-encased Concrete Composite Beams

Based on the analysis of some problems about the common I-section steel-concrete composite beam, our study group puts forward a new type of T- section steel-encased composite beam. Compared with traditional composite beams, the new type of steel-encased composite beams have the advantages of improvements in the flexural capacity, the fire-resist capacity and the comprehensive economic index of the beams, and the convenience of construction process. However, the T- section steel-encased composite beams have two slip interfaces, not only the partial shear connection T- section steel-encased composite beams but also the full connection T- section steel-encased composite beams have interface slip. Interface slip can reduce composite effect of section, which lead to the deflection of composite beams increasing. So Interface slip is an important factor in composite beams design. Test research, theoretical analysis and computer simulation have been carried out in this article to study the new type of composite beams. The details are as followings.(1) Slip equation and slip strain equation under two interfaces of the new type of composite beams are derived by theoretical analysis, establish the relationship between slip and shear connection coefficient.(2) Based on simple theory of plasticity of section, the paper deduces ultimate flexural capacity calculation formulas of partial shear connection composite beams. Utilization of the slip strain equation of this paper, the calculation formulas of mid—span deflection are deduced also.(3) Three full size simple supported specimens with different shear connection of this type of beams have been tested. According to the experiment, a set of load- slip curves, load- deflection curves and load-strain curves are derived. Based on these results, the interface slip development process and distribution laws are gained. The results of those theoretical formulas are proved to be in good agreement with the experimental data.(4)Some elements and modeling methods of analysis soft-ANSYS related with composite beams are introduced in this paper, and establish a nonlinear finite element analysis model by using ANSYS. The results of finite element model are in good precision with experimental results on stress, strain, deflection, and slip of composite beams. Further numerical simulation is conducted by the nonlinear finite element method, and gains the interface slip distribution laws and character of deflection of the new type of composite beams with different shear connection coefficient.(5) Finally, Construction design suggestions and study expectation of this new type of steel-encased concrete composite beam are advanced according to the results of test research, theoretical analysis and computer simulation.