Key Technical Methodology For Post-tension Concrete Deck On Elevated Multi-span At Baite Super-large Bridge

Based on project case of Baida Extra-large Bridge construction in Jing Na Expressway Lot3 in Guangxi Province, this article researched on the key techniques in the construction of the continuous rigid frame bridge with high pier and large span.(1) The turnover formwork and inserted lift scaffold method are used in the construction of thin wall high pier to ensure safety of the workers. Locate the turnover formwork with the combination use of high-precision total station and laser plummet, as data analysis indicates, mutual inspection between these two method insures the verticality of high pier construction.(2) Using temporary concretion method on the sand box on the pier top ensures the stability and safety of continuous beam construction and easy demolishing of temporary support. And also ensure the totality, reasonability and reliability of atress calculation by using MIDAS CIVIL 2010 FEM calculation on temporary concretion of pier and beam, and conducting modeling analysis on 0# bracket and hanging basket construction.(3) Monitor the stress-strain of thin wall pier and main beam by using informationalized monitoring technology, which makes stress- strain of bridge construction is under control. Conduct atress analysis on pier and box girder construction of the entire bridge by modeling analysis with ASCB program, analyze theoretical atress during bridge construction and compare with monitored data on the site, ensure the structure safety and line-type accuracy by controlling both theoretical and monitored data.(4) Through increasing unbalanced cast-in-place cantilever of side span, optimize and shorten the cast-in-place length of side span. After optimization, use bracket construction with no balanced counterweight to solve the construction difficulty of cast-in-place high side pier and large span in complex geology place, which enhances construction quality and increases the construction efficiency.(5) Optimize and adjust the fold sequence of multi-span continuous rigid frame, firstly fold the middle span and secondly fold the side span, which eliminates the effects of unbalanced cast-in-place cantilever, and fastens the construction of upper box girder.