Optimal Design Of The Frame Composite Beam’s Negative Moment Region By Coverplate

The steel-concrete composite beams are fully exert the compressive strength of the concrete and the tensile properties of the steel beams through the shear connectors.Steel-concrete composite beams used in frame structure can make structure system with small cross section and low cost, high carrying capacity and stiffness, well improve the frame beam’s load-bearing capacity, which has a broad application prospect in engineering.The load carrying capacity of the frame composite beam in the negative bending region is much lower than that in the positive moment region, and it is a weakness. The optimization methods of composite frame beams by adding coverpate in the negative moment area, can effectively enhance the flexural bearing capacity of composite frame beams in hogging moment area, improve the local stability of beam and the seismic energy dissipation capacity.The main research contents of this paper include:1) Study on the rationality and the improvement degree of the frame composite beam’s bending capacity with cover plate in the negative moment region. Determine the size of the coverplate and the connections between coverplates and the steel beam.2) Based on the code, It is derivated that the bearing capacity calculation method of the frame composite beam with coverplate in negative moment area, based on the the simplified model under bending and shear, the optimization calculation method is also derivated. The overall stability and local stability of the composite beams are studied, and the limit values of the height thickness ratio of the web are derivated.3)By ABAQUS finite element simulation,It is studied of steel-concrete frame composite beams with coverplate compared to without it to verified calculated results.Through theoretical derivation and ABAQUS finite element analysis, the following conclusions and results are obtained:1) By theoretical calculation and ABAQUS finite element analysis, composite frame beam with coverplate can effectively improve the composite frame beam’s flexural bearing capacity, the reasonable design size of the cover plate is also given.2) Based on the calculation theory of the code, the corresponding calculation method for the optimization of the cover plate is derived. The simplified calculation method under bending and shear condition is given.3) composite frame beam’s global stability and local stability of compression flange don’t need to be considered is proved by theory analysis and engineering, additionally, paper provides the local stability of the web’s height thickness ratio limit.