Study On Performance Of Steel-encased High Strength Concrete Composite Beams

The steel encased high strength concrete composite beams, a new type of composite beams, are formed by encasing the high strength concrete into the U-shaped groove welded by cold-formed sheets and a thick steel plate.The two parts of steel encased high strength concrete composite beams cooperate with each other by the shear connectors such as the shear studs on the interfaces. The research results reveal that steel encased high strength concrete 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, compared with traditional composite beams. The computer analysis and the theoretical study on the steel encased high strength concrete composite beams is presented as follows:(1) The behaviors and load bearing capability of the steel encased concrete composite beams,including failure modes, load-deflection curves, load-strain curves, thedistribution of strain along the height diretction of beams are tested from the static test of six simply supported specimen. And the validity of theoretical models is verified.(2) The failure mechanism and mechanical characteristics of this composite beam are discussed through theoretical analysis, Two particular kinds of failure mode of the composite beam with U shape steel plate-encased high strength concrete are discussed with emphasis, which are the longitudinal oversize slip failure and the longitudinal horizontal shear failure. And the effect of the form of U shape steel beam top flange on mechanical behaviors of composite beam is reasearched.(3) The complete design methods for the composite beam with U shape steel plate encased high strength concrete are provided on the foundation of theoretical analysis,the computational formulas of four kind of bearing capacity in limiting state and the computational formula of deflection are provided.(4) The nonlinear finite element analysis of the steel-encased high strength concrete composite beams is accomplished by using ANSYS, The behaviors and load bearing capability of the steel-encased high strength concrete composite beams are further reasearched, And the validity of theoretical models is verified. The economical section of the steel-encased high strength concrete composite beams is ascertained by the use of the optimization parts of ANSYS.(5) Finally, construction design suggestions and study expectation of this new type of steel-encased high strength concrete composite beam are advanced.