Research On Key Technology Of Design Of Cast-in-place Continuous Box Beam By Hole By Hole Construction

The hole-by-hole construction method of bridges has the characteristics of standardized construction process,periodic work,high turnover rate of support formwork,and low total cost.It is increasingly used in medium-span long and medium-span bridges.Based on the construction of Dong guan Dong ping Bridge project 5 * 40 m span continuous box girder by hole casting as the background,through the MIDAS CIVIL and other finite element software platform,the key technology of hole-by-hole construction of continuous box girder design is studied.This paper mainly studies:(1)One-way cantilever construction or two-way cantilever construction in hole-by-hole construction.Through the analysis of the total construction period and the turnover of support formwork,one-way cantilever construction is more appropriate.(2)Selection of construction joints for hole-by-hole construction.Through finite element numerical simulation analysis,the L/5 of the bridge is closer to zero bending moment.(3)Selection of girder height and web thickness for hole-by-hole construction of bridges is analyzed from the aspects of structural stress,overloading factors and structural requirements.Increasing the girder height and web thickness of equal-height girder appropriately will increase the amount of concrete and steel bundle,but will increase the structural resistance greatly,which is very beneficial to the structural safety reserve.According to the characteristics of the bridge and the construction level of the construction unit,the arrangement of the main construction process is made clear.First,the most disadvantageous position is selected for preloading,then the whole preloading method,the installation and tension of the prestress,the concrete pouring and curing process requirements.Through the study of this paper,the reasonable section size and construction process of this project are determined,which provides a scientific basis for the economic and safe construction of the bridge,and provides a certain reference value for the design and construction of similar bridges in the future.