The Optimization Analysis Of Large Span Composite RHS Truss Without The Top Chord Based On The Optimal Matching Degree

As in recent years the rapid development of national economy and people’s material lifelevel requirement is increasing day by day, Construction industry towards large column grid,large space, and larger space of the monolayer and multilayer large-span spatial structuredevelopment on a large scale, New stadiums, convention and exhibition venues such as largespan structure puts forward new requirements on the floor structure, Composite floor becauseits superior performance, gradually favored by structure engineers. And the composite RHStruss floor structure which developed on the basis of the composite space truss floor, has ahigher integral rigidity and bearing capacity, under the condition of equal amount of steel, is avery promising new space combination structure forms, but there is a lack of attention,scholars at home and abroad to the relevant theoretical calculation and design method is notperfect. In this paper, in reference to the research achievements of predecessors and, on thebasis of elementary bending theory, using the finite element software ABAQUS to no windingcomposite tube failure mode, ductility and ultimate bearing capacity of truss is analyzed.From RHS truss bar section size, depth-span ratio, aspect ratio, concrete slab thicknessand plate concrete strength grade five aspects of the comprehensive analysis of the ultimatebearing capacity, failure mode, the load-displacement curve, and displacement ductilitycoefficient of mechanical performance, puts forward key parameters affecting the mechanicalperformance-----the matching degree η of lower chord and the top flange concrete plate.The conclusion: Use set the top chord between end nodes, steel plate on other node and acertain number of shear bend-up in the concrete board, can effectively avoid nodes andpedestal brittle failure. Aspect ratio to improve the effect of stiffness and ultimate bearingcapacity of composite RHS truss is not obvious, even when the aspect ratio greater than0.8, itwill reduce the stiffness of composite RHS truss or ultimate bearing capacity, therefore, on notop chord composite RHS truss design process, aspect ratio of0.8can be used as a limit.Brought forward the optimal matching degree η=1.20which can make no top chordcomposite RHS truss has a good mechanical performance under the commonly useddepth-span ratio, aspect ratio, thickness of concrete and the strength grade, avoid structure on the flange crushed before the bottom chord tube tensile concrete is brittle failure. Forsubsequent research and give some reference to engineering practice.