Study On Creep Behavior Of Prestressed Concrete Beams Of Fold-line Pre-tension And Post-tensioned

The technology for construction of the fold-line pre-tension method has many advantages over the straight-line pre-tension method and the post-tensioned method,and its popularization and application in engineering have good social efficiency and economic efficiency. In bridge engineering, deformation of component under long-term loads has been a concern of the engineering field, selecting the appropriate data of concrete creep is crucial to prestressed concrete bridge. Combined with the National Natural Science Foundation-funded project "study on the force properties of HRB500 level reinforced concrete structures" (NO.50578148) and the Transportation Office of Henan province-funded project "study on a set of suitable techniques of the broken-tendon of pretensioned pre-stressed concrete beams" (NO.2005P338)the deflection and strain data of three fold-line pre-tension pre-stressed and one post-tensioned prestressed simple supported beams under long-term loads with 500MPa high strength steel bars are observed. Using experimental data and large-scale finite element software the research work on the following aspects were mainly done with characteristic parameter based on time such as creep deflection, creep coefficient:(1) The detailed comparison and commentary on the characteristics and theoretical principle of concrete creep are carried out, combining the present analysis of the mechanical behavior of concrete, basic theory and creep prediction model of creep effect are discussed, the way of selecting creep prediction model of creep effect analysis are pointed out.(2) Based on the deflection and strain observed data of three fold-line pre-tension pre-stressed and one post-tensioned prestressed simple supported beams under long-term loads with 500MPa high strength steel bars, characteristic parameter based on time such as creep strain, creep deflection, creep coefficient is analyzed, the formulas of creep strain coefficient and creep deflection coefficient for the beam of fold-line pre-tension pre-stressed and post-tensioned pre-stressed are suggested. (3) Based on linear creep theory using large-scale finite element software, creep effect is analyzed with constitutive relation of metallic creep, and its analysis results are contrasted and analyzed with test measured value.