The Experimental Study On The Steel Encased Concrete Composite Beams

The steel encased concrete composite beams, a new type of composite beams, are formed by encasing the concrete into the U–shaped groove welded by cold-formed sheets and a thick steel plate. The two parts of steel encased 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 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 experimental study and the theoretical study on the steel encased 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, the distribution of strain along the height diretction of beams are tested from the static test of 14 simply supported specimen. And the validity of theoretical models is verified.(2)The steel encased concrete composite beams with full shear connection are under the plane strain assumption, and the two parts of the ones with partial shear connction are under the plane assumption respectively, the formulae for the calculation of the ultimate flexural capability of the steel encased concrete composite beams with full shear connection and the ones with partial shear connection are deduced in this paper. Comparison between the calculation results and experimental data validates this method is correct.(3)Considering longitudinal slip effect on the deflection and rigidity, theoretical calculation formulae on the deflection of steel-encased concrete composite beams in elastic term are deduced in this paper, furthermore according to the reduced rigidity method, practical formulae for the deflection and rigidity of this kind of beams are proposed. According to this method the calculation results are in good precision with the experiment data.(4)The function on the longitudinal shear failure of the three week planes of the steel encased concrete composite beams is introduced and the design and calculation for the shear connectors in the three planes are given.(5)The nonlinear finite element analysis of the steel encased concrete composite beams is accomplished by the secondary empoldering based on the APDL language of ANSYS, a large-scale finite element analysis program. The nonlinear properties of the material and contact are put emphases on together with the rules on the relative splitting that are difficult to be tested because of the limitation of the experiment condition. The economical section of the steel encased concrete composite beams is ascertained by the use of the optimization parts of ANSYS.