Research On Closure Construction Control Technology Of Long-span Hybrid Beam Cable-stayed Bridge

The main span of hybrid girder cable-stayed bridge adopts steel box girder and the side span adopts concrete girder,which has the characteristics of large span capacity and low construction cost.Since its inception,it has been widely used.With the increasing span of hybrid girder cable-stayed bridge,construction control plays a more and more important role in the construction of cable-stayed bridge.For super-long-span hybrid girder cable-stayed bridges,mid-span closure is particularly important.Taking the Shishou Yangtze River Highway Bridge as the engineering background,this paper studies the construction control of the closure process of the Shishou Yangtze River Highway Bridge.the research contents are as follows:(1)The closure construction method,construction technology and construction control monitoring system of Shishou Yangtze River Highway Bridge are introduced in detail.In the maximum cantilever state,the measured main beam alignment and structural stress data are compared with the corresponding theoretical calculation values,which shows that the actual state of the structure before closure is in good agreement with the theoretical expected state.(2)Under the maximum cantilever state,the width of the closure mouth is continuously monitored for 48 hours,the embedding time of the closure section is determined,and the temperature effect of the cable,beam and tower structure is theoretically analyzed.combined with the measured data,the absolute temperature limit and temperature difference limit of cable,beam and tower are put forward.(3)When avoiding the influence of gradient temperature,the influence of the inconsistency between the actual closure temperature and the reference temperature on the bridge state of the structure is theoretically analyzed,and the method of reducing the influence on the bridge state by unilateral pushing and the calculation method of pushing stroke are introduced.The effect of unilateral pushing is verified by finite element theoretical calculation and analysis,and the relationship between unilateral pushing stroke and traction is determined.(4)The force of the temporary fittings under the possible temperature load before the welding is completed after the closure section is locked is theoretically calculated and analyzed.the calculation results show that the temporary consolidation under the south tower should be released in time after the closure section is locked in order to reduce the temperature stress safety risk of the temporary fittings.