Research On The Influence Of Lateral Restraint On Prestress Effect In Frame-shear Wall Structure

The post-tensioned prestressed concrete structure,the existing norms and procedures are based on the working principle of the end of the unconstrained beam to establish the formula to its structural crack test,cross-section bearing capacity calculation.Therefore,the prestressed structure of the simply supported beam,continuous beam and no lateral restraint is suitable.For the prestressed structure with lateral restraint,the lateral constraint of the vertical member has a certain axial deformation of the prestressed beam,The effect on the prestressing of the prestressing beam causes the prestressing force reduce,resulting in the prestressing loss of the prestressed beam.The prestressed structure is adopted in the frame shear structure,and the lateral stiffness of the shear wall is relatively large,which has a great influence on the effective prestress.In this paper,the prestress loss of the single-span,multi-span and multi-layer prestressed beams in the frame-shear structure are studied by using the equivalent load method and the finite element software SAP2000 to calculate the modelin in the background of the New World Commercial Center project in Yuzhong County,Lanzhou City.The prestress loss law of prestressed beams under different tensioning schemes is discussed.Based on the domestic and international research results,the measures to reduce the effect of lateral restraint on the prestressing effect are given from the aspects of design and construction.The main conclusions are as follows:(1)The greater the lateral stiffness of the shear wall,the greater the prestress loss value in the beam.As the span of the beam increases,the greater the prestress loss value in the beam;the prestressing loss of the beam under different tensile forces Values are approximately the same,and the magnitude of the tensile force has no effect on the prestressing effect.(2)With the increase of the number of spans,the larger the lateral components,the larger the lateral constraint,the greater the maximum prestress loss value in the multi-span structure;The maximum prestress loss value of the shear wall near the intermediate span beam in the multi-span structure is the smallest,that is,the effect of the lateral constraint on the prestressing effect is smaller as the lateral constraint is closer to the middle.(3)The maximum prestress loss value of the beam is at the lowest level when the multilayer structure is tensioned at one time.The maximum prestress loss value of the beam appears at the top level when the multilayer structure is tensioned layered by layer.(4)Different tensile construction methods,reasonable construction sequence of the mixed construction can avoid the one-tine tensioning method and layer by layer tensioning method of the most adverse effects.