Experimental Study And Parametric Analysis Of Mechanical Properties Of Thin-walled Steel Truss Beams

Steel structure,composite structure and thin-walled steel truss structure have been widely used under the background of our country's vigorous promotion of prefabricated buildings.The thin-walled steel truss beams assembled by chord members and web members by self tapping screws have the advantages of standardized design,factory production and assembly construction.But the thin-walled steel truss beams have uncertain factors in bearing capacity and damage form.Therefore,this paper adopts experimental research and finite element simulation to discuss the mechanical properties and failure modes of thin-walled steel truss beams.In this paper,seven specimens of thin-walled steel truss beams under two spans,which connector have different types and orientations,were firstly tested under vertical loads.The test results showed that the relationships between the bearing capacity,the deflection of the thin-walled steel truss beams and the span of the thin-walled steel truss beams,the type of connector,the opening direction of connectors,which indicated the following rules: When the other parameters were the same,the span of the truss beams increased from 3000 mm to 6000 mm,the bearing capacity of the truss beams decreased significantly and the mid-span deflection increased approximately twice;when the other parameters were the same,the truss beams were replaced by a large medium-sized connector,which increased the bearing capacity and reduced the deflection;when the other parameters were the same,the bearing capacity of the truss beams were obviously increased and the deflection decreased when the connection type of the truss beams were changed from the medium one to the large one;when the other parameters were the same,the bearing capacity of the trussed beams with the opening upwards of connectors was greater than the opening downwards of connectors;During the loading process,the first buckling part was the local buckling failure of the connectors at both ends,and it would occur that the overall loss of stability of the truss beams as the load increased.Secondly,considering the geometric non-linearity and material non-linearity,the finite element model of the truss beams were established by using the finite element softwarewhich is called ABAQUS,and the connection mode was optimized between the chord pipe and the connector.By comparing the results of the finite element calculation and the experimental results,it were verified that the effectiveness of simplifying the connection mode by using the node domain and the plane "TIE" as well as the correctness and feasibility of the modeling method of the finite element.In the end,it was carried out that the finite element analysis of variable parameter about the mechanical properties of thin-walled steel truss beams combined with the application requirements in the practical engineering.The analysis results showed that the increase of the height of section of the top tube and the bottom tube,the increase of the wall thickness of top tubes and the increase of the connection parts improved the load bearing capacity and rigidity of truss beams in varying degrees.But for the same span,the growth gradient of truss beams bearing capacity and rigidity became slower when the component parameters increased to a certain value.The study of this paper provided a reference for the node simplification and simulation of thin-walled steel trussed beams.It also provided a method for optimizing the selection of component parameters for the application of thin-walled steel truss beams in practical engineering.