Spot-test Analysis And Research On Static Behaviors Of Large Prestressed Concrete Laminated Transfer Truss

Transfer truss is an important transfer structure type in modern high-rise building.Combined with Shanghai Yunian International Commercial Affairs Building,static analysis and static test of prestressed concrete laminated transfer truss structure are studied as well as spot-test.The static analysis of laminated transfer truss under vertical load function are carried out on the analytical background of laminated transfer truss of Shanghai Yunian International Commercial Affairs Building,and on the analysis factor of different superstructure form,different layer as well as substructure layer,the finite element computation model of laminated transfer truss is concluded. When the upper part of laminated transfer truss is frame structure,the upper part can use 1 storey,the substructure use 3 storey; when the upper part of laminated transfer truss is shear wall structure ,the upper part can use 4 storey,the substructure use 2 storey. It shows that the calculation accuracy can meet the engineering design requirements according to an analysis model of the propssed model.The reasonable structure form of laminated transfer member is explored,and the internal forces of reinforced concrete single transfer structure are analysized and compared, which including deep beam,laminated vierendeel truss, laminated level strut truss and laminated k type truss. It shows that the vertical external load P of laminated level strut truss is transfered by the arch structure which is composed of down chord(pull rod)+diagonal web member(pressure lever)+top chord(pressure lever);laminated level strut truss has reasonable bearing forces and clear forces transmission way, which can been used as transfer member of this engineering.Static test of a 1:8 proportion laminated truss under the vertical load are carried out.Test shows that prestressed concrete laminated transfer truss can meet the requirement of bearing capacity and deformation,and it is at the elastic condition in the service stage;The oblique flank rod between vertical load loading point and the down chord node of truss bear larger axial pressure, the cracks parallel to the longitudinal axis occurre when it damages,it is similar to the axial center compression member;the destruction of laminated truss test model starts with the concrete crushing of the connected subcolumn section compression zone.In this paper,SOLID65 unit and LINK8 unit are used to establish the overall model, prestress are imposed through the cooling method, and nonlinear analysis of laminated transfer truss are carried out. The corresponding load deflection curves are obtained,and compared with the test curves. The theoretical results of imposed prestressing stage coincide with the test results, but the difference between vertical load function stage and the test results of theorectical analysis is larger.The spot-test of laminated transfer truss on construction process is carried out. It shows that the measured values are in the design of control;When post pouring belt is not set up between the chord and the floor,the floor which undertakes part of prestress should be considered.