Construction Monitoring And Research Of The New Built Zhijiabao PC Extradosed Cable-stayed Bridge

Extradosed cable-stayed bridge is a new bridge between continuous girder and cable-stayed bridge.In the range of 100-300 m span,extradosed cable-stayed bridge has superior technical and economic advantages.Coupled with the aesthetic characteristics which combine vigor and suppleness,it has been favored by the a lot of bridge builders since the first extradosed cable-stayed bridge was built.In this paper,based on the Zhi jiabao prestressed concrete extradosed cable-stayed bridge,the large finite element calculation software Midas/Civil is used for modeling and analysing.For this extradosed cable-stayed bridge,the cables are tensioned two times before put into use.In order to achieve a reasonable bridge state,influence matrix method and the difference method are used to calculate cable force of the secondary cable-adjustment.The advantages and disadvantages of the two methods are compared and analyzed.And the level that the secondary cable-adjustment influences on the alignment and stress of the main beam is also analyzed.There are some geometric nonlinear problems such as sag effect,the beam column effect and the large displacement effect in the process of construction.This paper focuses on the degree that geometric nonlinearity affects on the alignment and stress of the main beam in the two typical construction stages.In the cantilever construction stage,the equal stress control technology is adopted for cable stretching.The magnetic flux method is used to measure the force of the cable.In the aspect of alignment monitoring,the elevation of formwork and the theoretical elevation of the current construction stage are emphatically introducted.The measured elevation and the theoretical elevation of the girder are compared and analyzed for the current construction stage.In the aspect of stress monitoring,the stress monitoring facilities and the layout of the stress measurement points of the main beam are introduced.The measured stress and the theoretical stress of the main beam are compared and analyzed for all construction stages.