Analysis Of The Bearing Capacity And Stress Re-distribution Of The D-Steel-Concrete Composite Beam

In traditional continuous steel-concrete composite beam the crack in the concrete that suffers negative bending moment grows easily and the bottom steel flange may appear "local buckling"or "overall buckling" and its bearing capacity weakens greatly.So the actual mechanical behaviour of the continuous beam conflicts with the "composite"purpose and this behaviour limits its popularize and application in civil engineering. However,the occurence of the D-composite beam gives a light and strong confidence to the way of solving this difficult problem.The "D-composite beam",to be brief,is the composite beam that another concrete slab is arranged and connected with the bottom steel flange with studs where this section suffers negative bending moment. In this way,the compress stress in the bottom steel flange and web is shared with the "help"of the concrete slab so their"burden" decreases largely which improves the rigid flexibility and bearing capacity of the beam.According to the present status of composite beam in the field of civil engineering in our country,this paper mainly researchs on the mechanical behaviour of D-composite beam,including its bearing capacity in elastic and inelastic state,the characteristics of stress and moment re-distibution and the slip property between the concrete and top flange.The research results prove that the bottom concrete slab may improve its bearing capacity greatly and decrease the compress stress in the bottom steel flange at the mid-support region as well as transfer the "stress peak"from the mid-support to mid-span.Another finding is that the relation between the degree of shear connectors and the bearing capacity and stress re-distribution of the D-composite beam appears to be complicatedly nonlinear,which should be studied further.The research shows that the re-distribution of the bending moment in D-composite beam appears more moderate than the traditional continuous composite beam and the extend of the bending moment re-distribution is not as obvious as traditional composite beam but the difference is rather small.The following research conclusion is that the slip law in the D-composite beam is almost consistent with the traditional composite beam.Through the study we may gain a preliminary insight into the mechanical behaviour of the D-composite beam which help to the further research subsequently.