Multi-objective Construction Control System For Long-span Prestressed Concrete Box Girder Bridge

The construction method is in high coupling of the design in long-span prestressed concrete box girder, the construction method and order is relevant to the configuration and internal force status of the finished bridge. In order to ensure the safety of continuous beam force and deformation during the construction process and operation period, to ensure the main beam linear in the bridge that fits the design requirements, and structure constantly stress state closes to the design expectations, strict construction control is needed in the continuous beam bridge construction.At present, the construction control of long-span prestressed concrete box girder bridge only adopts double control of configuration and internal force, and especially the configuration control. Generally,the box girder cracking and long-term deformation control are not included. However, box girder cracking and long-term midspan deflection are the defects which commonly exist in the long-span prestressed concrete box girder bridge. According to the project of the beach bridge of Jingyue Yangtze River Highway Bridge, this paper puts the box girder cracking control and long-term deformation control into construction control. The author proposes the multi-objective construction control system in the long span prestressed concrete continuous box girder bridge and introduces how to carry out the multi-objective construction control system in prestressed concrete continuous box girder bridge.(1) Introduce the main test contents of the multi-objective construction control system in the long span and long unit prestressed concrete continuous box girder bridge:the test contents not only include main girder deflection, the section stress and the temperature, but also add a series of test content and protective measures to prevent box girder cracking and long-term deformation.(2) Analyze the main reason of box girder cracking. Put forward a set of effective measures on controlling box girder cracking through material selection, concrete mix proportions, hydration heat test, mechanical properties of concrete at early ages, and prestress loss test, etc. Besides, put the measures into the background work and obtain good results to avoid the box girder cracking in the construction process of background work.(3) Obtain the main and the minor factors effected long-term deformation, basing on sensitivity analysis about box girder cracking and prestress loss. And propose some main measures on controlling long-term deformation.(4) In the system transformation process, displacement calculation is quite different from the actual project. Analyze the effects on system transformation from elastic modulus, prestress loss, and bridge pier by adjusting the parameters to modify calculation model.