The Research Of Bearing Capacity Of Prestressed Space Steel Pipe Truss Exhibition Hall

The prestressed space steel pipe truss structures can be widely used in the large public buildings,such as airport terminal,theaters,stadiums and exhibition centers,because of its beautiful shape,higher economical and long span capacity.Comparing with the traditional reinforced concrete structure,lightweight and high-strength,economy and saving materials are its biggest advantages.Since this type of structure appears relatively late,related fundamental research is not complete.The research on the tube truss structure is mainly focused on the bearing capacity of intersecting joints,static and dynamic stability.Few studies concentrate on the response of steel pipe truss structure when actual load exceeds design load.For instance,exhibitors often hang lighting of ornament or signs on the joints of bottom chord during exhibition.Combining with the requirement of actual engineering,study on hanging capacity of prestressed space steel pipe truss structure bottom chord joints has important theoretical significance and practical value.Considering actual hanged weights on bottom chord nodes of Chengdu New International Convention and Exhibition Center during exhibition,load-response of this prestressed spatial steel pipe truss structure under design load was analyzed and calculated by MIDAS/GEN software in this dissertation.Then the ultimate bearing capacity of concrete filled steel tube was calculated by ANSYS,which is several times to maximum vertical reaction force of the truss structure under design load.This simulation result reveals that the upper roof truss is the weak link of the exhibition hall under load,therefore the research of this dissertation will be focused on the upper roof truss.Using material strength and local stability of the truss components as controlling properties,residual bearing capacity of bottom chord joints of the exhibition hall was obtained.ANSYS was employed to build finite element model for local part of the truss and check its strength under design load and bottom chord joint hanging load.In order to grasp bearing capacity of the roof truss fully,this dissertation chose two influence factors,which are prestress loss and initial geometry imperfection,to calculate bearing capacity of the truss.The results prove that prestress loss nearly hasno effect on bearing capacity of the roof truss,but the bearing capacity decreases linearly with increase of the initial geometry imperfection.The hanging experiment on bottom chord of the roof truss was carried out based on FEM simulation.The experimental results show that the distribution of 2 truss’ monitoring data are basically consistent with numerical calculation results under hanging load of the experiment,the measured results are smaller than calculation values,and deflection and strain have an good linear relationship with experiment load.The deflection of the truss will disappear completely when experiment load is removed,which means that the structure is still in elastic state,and it still has safety margins under experiment load.Based on numerical simulation and in-situ hanging experiment,a hanging scheme was proposed to conduct exhibitors to hang weights.