Research On The Application Of The Externally Prestressed Technique In Continuous Rigid Frame Bridges

This thesis,based on the summarization and conclusion of Externally Prestressed prestressed concrete bridges at home and abroad, carried out the following researches via the background of new Beach Qijiang Bridge of southwest of Highway in Chongqing:(1)On the basis of analyzing the main disease and causes for these,this thesis proposed that external prestressing technique applied in continuous rigid frame bridges is a feasible way in solving the disease in them;(2)Based on full-bridges (internal and external prestressing concrete continuous rigid frame bridges) finite element model, the thesis compared and concluded the differences and similarities of internal and external prestressing concrete continuous rigid frame bridges from the aspects of structure,the way of designation, mechanical properties, construction technology, as well as technical and economic aspects, especially paid attention to the mechanical properties, advantages and also its problems and developmental trends of external prestressing continuous rigid frame bridges;(3)Does the researches on the construction technology of external prestressing continuous rigid frame bridges, including the arrangemen, tension,adjustment, replacement, protection, Anti-vibration measures of external prestressing steel strand;(4)In combination of the actual situation of this engineering,Optimized the section geometry, reasonable alignment of Box Girder Floor and Box Girder height; Analyzed the impact in external prestressing concrete continuous rigid frame bridges Tensioning external prestressing steel strand; explored the initial tension of external prestressing cable and the second tension time and tension analysis;(5)Proposed new idea of applying vertically tensioned prestressing technique in external prestressing concrete continuous rigid frame bridges;Discussed a kind of structure and construction technique that can be easily controlling the main beam displacement and stress state through adjusting external prestressing steel strand to expected extent by vertically tension timely and compared it with traditional technique, provided a referenced development ideas for the long-span external prestressing continuous rigid frame bidges.