Sheme Selection And Analysis On Large-Span Roof Structure

Large-span space steel structure system has developed most rapidly in civil-engineering.Choosing different structure forms in different conditions,taking the optimal design for structure,has become a quite valuable question.This paper is based on a practical engineering project which named Tangshan east lake conference and exhibition center roof structure(100m span).The ultimate goal of this paper is to provide a reference for the subsequent design of China architectural design institute.This paper uses the finite element analysis software to analyze the system selection among space truss structure,beam string structure and cable-supported structure.Through analyzing the parameters——stress performance,economic performance and the overall stability of the structure,the optimal structure design scheme is obtained.The seismic performance is analyzed based on the structural design scheme.The specific research contents and main conclusions are as follows:(1)Model of space truss structure,beam string truss structure and cable-supported truss structure are built in MIDAS,this paper analyzes the scheme selection under the premise of structural deformation meeting the specification and structure of the bar used sufficiently.From the view of structure performance,the cable-supported structure can decrease the maximum axial pressure by 30%-40%.From the view of the deformation and the amount of steel,the cable-supported structure uses 38.55kg/m 2,the beam string truss structure uses 67.01kg/m2,the space truss structure uses 81.07kg/m2.(2)The single model of cable-supported structure is built in MIDAS,on the premise of controlling the average between structure material and dosage,cable-supported node location,cable initial prestress level and the tower height have a comprehensive effect on the stress performance.In the one third across of cable-supported structure,the mechanical performance is quite well.The higher of the initial prestress level is,the better the mechanical performance is.The center position of the cable tower height,between 8 to 12 meters range,has a better mechanical performance.(3)The whole model of cable-supported structure is built in MIDAS,on the.premise of controlling the deflection that meets the requirements of specification and the bars of structure which are used sufficiently,the amount of steel decreases at first and then increases as the change of cable-supported node location,cable initial prestress level and the tower height.The structure has the best economic performance when the cable-supported is at the one third cross,the initial prestress level is 0.35 and the height of the cable tower is 8 meters.(4)The stability analysis of cable-supported is done both in MIDAS and ANSYS.Cable-supported node location,cable initial prestress level and the tower height affect the in-tergral stability of cable-supported structure.When cable-supported nodes are between 39m-42m,the stability of the structure is the strongest.As the increase of initial prestress level of ascension and the height of the tower,the stability of the structure increases.(5)With the antiseismic performance analysis in MIDAS,the cable-suppuorted structure is sensitive to vertical seismic action,and the vertical seismic design should be taken into account in the design.The displacement and reaction force of the structural seismic analysis and vibration response analysis are obviously larger than those obtained by elastic time history analysis.The envelope of the two values should be taken into design.In the rare earthquake only appeared in the primary plastic hinge,first appeared in the cross position,then appeared in the bearing position.According to the distribution of plastic hinge and two methods of internal force comparison,bearings and mid-span position are weak parts of the structure,in the seismic design should be taken seriously.