Construction Monitoring Research Of Auxiliary Line Bridge Of The South-to-North Water Diversion Bridge Of Zheng Shao Connecting Line Project

The construction of rigid frame-continuous combination beam bridge has greatdifficulty, in order to ensure the bridge is in a safe state during the constructionprocess, the smooth closure of the girder, the bridge deformation and structureinternal force to meeting the design requirements, the bridge construction monitoringis very necessary. Based on Long-span prestressed concrete rigid frame-continuouscombination beam bridge of the south-to-north water of zheng zhou to shao linhighway road connecting line project, this paper mainly formulate the constructionmonitoring scheme, implement the construction monitoring, and do the research onthe main girder closure of key technologies. The main work completed and researchconclusion are showed as follow:1．The whole construction process is simulated by auxiliary line bridge finiteelement model which established by the finite element software Midas/Civil. Throughthe sensitivity analysis of main structural parameters, the results show that thedeadweight affect the main girder deformation most, and the elastic modulus ofconcrete secondary, then the prestressed channel deviation and effect coefficient least.Construction should control the parameters with more effect on structure strictly andcorrect theoretical calculation model parameters based on the actual situation.2．The bridge construction monitoring scheme is formulated according to theStructural features of auxiliary line bridge. Based on the adaptive control theory, themonitoring work is developed with the principle of taking deformation controldominated and stress control assisted. Site monitoring include the aspects of stress,deformation and temperature. In that way, the stress and deformation of main girderare investigated in time through the real-time monitoring of main girder at everyconstruction stage, which provide evidence for correction model and predict the stressand deformation for next girder.3．During the site monitoring of bridge, Least square method is used to identifyand adjust the structure parameter based on the actual situation. By correcting calculation model parameters constantly and predicting and adjusting the formworkerection elevation of next girder accurately can guide the construction site, make thebridge closure smoothly and keep safety in the whole construction process. Bycomparing the practical values and theory values, it shows that the stress anddeformation measured values can better approach the theoretical values, and that themonitoring effect is good.4．Taking the influence of the temperature difference of bridge closure to jackingforce of middle span into account, the designing jacking force can be optimized.Having concluded the linear relationship of jacking force and horizontal displacementalong the bridge and the temperature change and horizontal displacement along thebridge, then the relationship between the temperature change and the jacking forcecan be turned out. Using the jacking force having been optimized into the incrementallaunching construction of auxiliary line bridge get better results.5．The closure sequence for bridge of auxiliary line is analyzed, considering theinfluence of different closure sequence to the force of girder and bridge deformation.the results show that the most reasonable closure sequence of auxiliary line bridge isto close the side span first and then close the middle span, which can reserve morestress for the structure to improve structure stress and reduce more vertical deflectionthan other programs. Although the vertical deflection of main span will increase overtime, the problem can be resolved by setting camber.6．Taking account of the influence of the removal time of full space supports ofthe cast-in-place beam of the side span to bridge deformation and structural force, theremoval time of full space support are analyzed. The results show that: comparedwith the removal time after the middle span close, the removal time after the sidespan close and before the middle span close can reserve more stress for the bridgestructure, at the same time, the upward deflection of main span is more than anotherprogram, it is more beneficial to the later deformation of main girder and structurestress.