Construction Optimization Of Simple-Made-Continuous Bridge Based On Support Reaction Forces

Simple-made-continuous bridge possessing both advantage of simply supported bridge and continuous girder ones has been widely used in the highways. Support reaction is a very important machanics indicator of simple-made-continuous bridge. Drastic change of it during construction process is extremely likely to cause partial failure, support sepration and even the dangerous circumstance of girder falling.The circumstance of uneven support forces during working will significantly shorten service life of supports.However, the current studies about support reaction of simple-made-continuous bridge is not sufficient.The current research results of construction sequence have serious problems in terms of support reactions, such as drastic change of support reaction and uneven support reaction.The main contents and contributions of present thesis are listed as follows:l)The present thesis states the deficiency of research in simple-made-continuous bridge and clarifies the significance on the basis of elaborating development process, common problems and research status of simple-made-continuous bridge.2)Employing the software, finite element models is established to analyse the mechanical properties during construction process of five-span, four-span bridge with prestressed steels in cast-in-place segments. Choosing the support reactions during the system conversion of simple-made-continuous bridge as the optimization objectives for optimization of construction program. The optimization results proposes an innovative three-stage program,namely,"concreting and prestressing the same cast-in-place segments,removing the temporary bearings of the same ones, repeat the steps with the others"("cast-in-place-segment-left") construction program.By comparing the analysis data with the measured ones, it vestifies the validity of the numerical simulation.In-depth study shows that the effect caused by optimization program to internal forces,deflections and stress is negligible, which implies the sensitivity of support reaction to construction process is higher than internal forces,deflection and stress.3)Employing the software, finite element models of five-span bridge without prestressed steels is established, following of which the support reactions is selected as optimization objectives for the optimization of different construction schemes. Analysing the impact on uniformity of final support reactions by controling the support settlement during the removal of temporary supports. Optimization results shows that the innovative program has obvious superiority in ability to keep support reactions even.4)From studying the impact of support reactions during construction process of simple-made-continuous bridge due to secondary internal forces effect of both prestress and support displacement, the formulas of support reaction influenced by secondary internal forces of prestress and support displacement is deduced. By comparing the MIDAS Civil simulation results with the formula calculation ones, the validity of formulas are demonstrated. These results conclude that the effect of secondary internal force of both prestress and support displacement is the dominant factor to influence the support reaction during construction.5)Based on the MIDAS software, three-span bridge model is established by the beam grillage method for analysing the impact coefficient of moving vehicle load and dynamic response of seismic action.