The Test Study Of Second-prestressing Precast Slabs Sandwich Of Serviceability Limit States

This thesis mainly researches second-prestressing precast slabs, It is important to study its one-way slab floor's ability in use.Specific content include: imitate construction load lab, through this method to analyze the precast slabs' properties in the first stage in burden load. One-way precast slabs' lab,analyes one-way precast slabs sandwich s ability in second burden load stage. We analyes post-tensioned prestressing properties and comparing with practiced results. We analyse one-way precast slab sandwich negative moment section resistant crack properties and two-way precast slabs sandwich under plane resistant crack at unprestressed section and second-prestressing propties .We compare canceling bonded reinforcement with laying on bonded reinforcement resistant crack properties and deformation .Auxiliary lab include:concrete resistant pollution intensity .concrete resistant compressing intensity and elastic modulus, compare with results of code.analyse sandwich's strain and long-time stress ,strain and introduce a new method through theory calculating long-time stress and strain.Based on the experimental results, in concrete limitation stress sandwich first stage's ability and one-way and two-way precast slabs sandwich, results content code require-second class crack control .Resistant crack calculation is appropriate. Because post-tensioned prestressed advances plane's resistant crack. Deformation and section strain measure accord with calculation results, this indicates 3D-gridding beams modulus is reasonable to precast slabs sandwich.