RESEARCH ON LONG-TERM CRACKING RESISTANCE OF NEGATIVE MOMENT SECTION IN COMPOSITE BEAM USING POST-TENSIONED PRECAST SLAB TECHNOLOGY

In the negative moment section of composite beams, concrete cracking and excessive deflections are easy to occur under the adverse conditions of tensioning. The long-term shrinkage and creep of concrete further aggravate these diseases and seriously affect the mechanical performance. In this study, an anti-cracking technology for post-tensioned precast slabs is proposed. The technology proposed is verified by numerical analysis upon a case study. In order to take into account the shrinkage and creep effect, an explicit/implicit time-varying effect program for ABAQUS is developed upon the AAEM algorithm of shrinkage and creep principle. The program of the time-varying effect and the finite element modeling is verified upon long-term experiments of composite beams. Results show that: The compiled prediction model of shrinkage and creep upon the AAEM method and modeling are effective, and identical to the experimental results with small error; The anti-cracking technology of post-tensioned prefabricated slab can effectively reduce the deflection and prestressing loss caused by shrinkage and creep; and improve the performance of the bridge. The study can provide a technical reference for cracking of negative moment section in composite beams and, a theoretical basis for finite element analysis considering the shrinkage and creep.