Study On Design Method And Parameter Rationality Of Steel Truss Web Composite Beam

Steel truss web composite beam is one type of new type steel mixed cooperative beam structure recently appeared.The steel beams are composed of concrete ceiling plates and steel girders,joined through joints,and received forces together,which effectively improves the mechanical performance of composite beam,as a result,the performance of the ceiling plate of concrete and the plate member of steel truss is fully demonstrated.At present,there is little research on steel truss web composite beams in China,and there is a large research space for the reasonable range of theoretical formulas and parameters.Through two test beams,combined with finite element analysis and theoretical derivation,this paper studies the effective width of the top plate of steel truss web composite beam,the slip effect at the interface,the flexural capacity of steel truss web composite beam,the vertical shear capacity of steel truss web composite beam,the influence degree of various parameters on the bearing capacity and the reasonable range of parameters.The main research contents and results are as follows:(1)The test beams of two steel truss web composite beams are designed and manufactured,and carried out static unidirectional loading test.Finite element software ABAQUS made the same size model as test beam.The deformation,loading capacity,and longitudinal strain of the abdominal bar were compared and analyzed,and the accuracy and feasibility of the analysis of steel truss web composite beams with ABAQUS are verified.(2)Using the method of formula theoretical derivation,according to the different positions of plastic neutral axis,the formula of flexural capacity of steel truss web composite beam is divided into two cases.Considering that the steel truss web does not bear bending moment,it is considered that the flexural capacity should be calculated according to the plastic neutral axis located in the roof.At the same time,the influence of slip effect cannot be ignored.The reliability of the formula was verified by testing and finite element analysis.(3)Based on the finite element method,multiple groups of steel truss web composite beam models are established,the influence degree of various parameters on the bearing capacity is analyzed,and the reasonable range of parameters is given.The results are as follows: the overhang wing ratio of concrete roof is 1.3-1.5,the width thickness ratio of concrete roof is 6.1-6.9,the longitudinal inclination angle of web member is 60 °-67 °,and the transverse included angle of web member is 90 °-110 °.(4)Combined with theoretical analysis and finite element method,considering the influence of longitudinal inclination and transverse angle of web members on the vertical shear capacity of steel truss web,the finite element results are fitted and the calculation formula of vertical shear capacity is established.Based on the existing theoretical formula of concrete slab,the influence of width-thickness ratio on the vertical shear capacity of concrete top and bottom slab is considered and fitted,and the calculation formula of vertical shear capacity is established.The vertical shear bearing capacity formula of steel truss web composite beam is obtained,and the correctness of the established formula is verified by shear calculation of finite element model.