Construction Control Theoretical Analysis Of Long Span Fully Prefabricated Composite Girder Cable-Stayed Bridge

With the continuous improvement of bridge construction level and the emergence of new technology and new materials,in order to improve the construction quality of the side-span concrete beam of the long-span hybrid beam cable-stayed bridge,the prefabricated hybrid beam cable-stayed bridge began to enter people's field of vision.At the same time,it also brought new challenges to the construction control of the bridge type.Based on the Shishou Changjiang Highway Bridge as the engineering background,the finite element calculation method is used to study the application of the stress-free configuration control theory in the construction control of fully prefabricated composite girder cable-stayed bridges.The corresponding construction control methods are proposed for the key construction procedures.The main research contents and related conclusions are as follows:Based on the construction characteristics of the fully prefabricated cable-stayed bridge,the construction control theory of the cable-stayed bridge based on the stress-free configuration control method is introduced.The calculation method of the stress-free configuration of the hybrid beam cable-stayed bridge is discussed in detail,including the unstressed linear shape of the main beam,the unstressed manufacturing dimension and the determination of the unstressed cable length of the stayed cable.For the prefabricated concrete main beam with short span,the calculation method of unstressed linear coordinate transformation based on Bursa-Wolf theory is adopted,and the longitudinal prefabricated linear correction method and lateral force safety control method for super wide short precast box girder are proposed.Based on the adaptive stress-free configuration control method,the construction control calculation analysis of the prefabricated composite beam cable-stayed bridge was carried out.The model of the Shishou Changjiang Highway Bridge was modeled and calculated by the planar bar system finite element software BDCMS.The structural stress-free control parameters were obtained,and the initial control tension was obtained through the unstressed cable length iteration.The obtained control parameters and tension were obtained.The calculation of the cable-stayed bridge is obtained by the force-fitted analysis.The calculation results show that the force and the line shape of the main beam and the main tower are good at the bridge stage,and the deviation between the calculated cable force and the design value is within 5%.The applicability of the stress-free configuration control theory in the prefabricated composite beam cable-stayed bridge can be verified.Based on the solution results of the stress-free control parameters,the structural response under key conditions during the whole construction process is calculated and analyzed,and the sensitivity analysis of the key parameters affecting the construction control accuracy is carried out.In the construction stage of the bare tower,the application scheme of the active cross bracing of the middle tower column and the anchor point coordinates of the modified tower end stay cable are given.The whole process of the main beam construction includes the structural safety of the maximum cantilever assembly stage and the bending stress is small.It is further verified that the stress-free configuration control theory has a good application effect in the full prefabricated assembled hybrid cable-stayed bridge.The calculation and analysis of the safety problems in the whole process of prefabrication and assembly of side-span concrete main girder are carried out.By analyzing the causes of the most unfavorable state of the concrete main beam assembling process,the corresponding control measures and suggestions are given.The lateral prestressing three-tensioning control scheme is proposed for the lateral safety problem of the concrete section short-line prefabrication process.The safety and shape of the concrete box girder segment are effectively controlled during the prefabrication process.