The Study Of Multi-span Rigid-frame Continuous Bridge Construction Stability And Closure Schemes

With its driving comfort, less expansion joints, reasonable stress, convenience ofconstruction, good adaptability to terrain and environmental coordination, continuousrigid frame bridges develop rapidly. It has become one of the most widely constructedbridges. With the pier height, span and length continuously increasing, meanwhile, thethin-walled and light weight high piers are required. However, the high and thin piersbrings the bridge the stability problems, which has become increasingly prominent. Toensure the safety and structural stability during the construction phase, it’s necessaryto analysis the stability of high piers during the construction phase. Meanwhile, duringthe closure of the multi-span continuous rigid frame bridge, it usually involves severalsystem transformations, and different system transformations make different impactson the stress and alignments of structures.In the paper, based on the Chengchuan River Bridge project, Midas/Civil finiteelement software was used to analyze the structure. The research content and someconclusions are presented as follows:（1）The5th Pier’s stability under-construction state (autologous state andmaximum cantilever state) and the bridge completion state stability are analyzed.Results show that the bridge is of enough stability under both under-construction stateand completion state.（2）Three different closure sequences are presented for the multi-spancontinuous rigid frame bridge. The effects of given closure sequences on the alignment,stress, internal force are analyzed. Finally, through comparison and analysis the secondclosure scheme, that’s mid-span first, then side span, finally the left span, is selectedas the closure sequence.（3）Based on the closure sequence, considering the deformation effect of the closuretemperature, shrinkage and creep on the bridge structure. To reduce their adverse effect,we used to exerting forces on the closure segment to make the pie r produce certaindisplacement in advance. In this paper, three jacking schemes are put forward, andjacking displacement and jacking forces are discussed. Meanwhile, the expression ofthe closure temperature and jacking force were deduced. Then based on t he actualclosure temperature, the effect of three different schemes on the bridge structure areanalyzed.