Study On The Dynamic Control And Management Techniques Of Large Complex Bridge Construction Process

As the pace of the state infrastructure construction speed up,the construction quantities and scales of large complex bridges grow with each passing day,which is followed by problems exsiting in construction.The internal force and line shape of structure change in each construction stage.Construction control is not only a key link between design and construction but also a hard work in the construction of large complex bridges.The quality of construction control plays a decisive role in the quality of the finished state of bridge.In thispaper,the longest prestressed concrete Short-Pylon Cable-Stayed Br idge——ShangDeng Highway Bridge cross the South-to-North Water Diversion(which is referred to as Bridge of South-North Water Transfer)is taken as e ngineering background.In order to guide the construction of bridge,the whol e construction process of bridge was tracked to research on the construction q uality of the main pier bearing platform,main girder,cables and cable-towers.The main research content is as follows:(1)The important significance of the large complex bridge construction process control was expanded,the development status and representative bridge of cable-stayed bridge and short pylon cable-stayed bridge were summarized to provide reference for the construction of Bridge of South-North Water Transfer.(2)The research status of construction control theory on the mass concrete construction quality control,especially the superstructure of the Bridge,is analyzed and summarized.The finite element models of hydration heat analysis was built based on the size of main pier cap,concrete mix proportion,proposed construction method and cooling pipe position to analysis the temperature fields and stress fields in different construction stages.Reprehensive nodes were selected to observe and study the difference in internal and external temperature,development trend of the stress and allowable stress in special parts and crack development.The sensitivity of temperature field and stress field in mass concrete to casting temperature,convective boundary condition and the flow rate of cooling water is researched.(3)According to the construction management plan,the FEM model of Bridge of South-North Water Transfer was built to conduct simulation analysis.The simulation result on the internal force,stress and displacement of girder,the displacement of cable-tower and the cable force was emphatically analyzed.According to the simulation result,the formwork elevation of each girder segment was provided,which provided the theoretical basis and guidance for the construction control.(4)Adaptive Control Theory was applied to the construction control of Superstructure.Concrete monitoring scheme for the Bridge of South-North Water Transfer was formulated and implemented,including line shape monitoring,stress monitoring and temperature monitoring.Implementation methods and means for every monitoring item are supplied.(5)For the parameters identification of adaptive construction control theory,different parameters identification method and their principles are introduced and compared.At last,neural network theory was selected as the parameters Identification method for the construction control of the Bridge of South-North Water Transfer.Three layers BP Neural Network model was established,which was trained and validated through training simple data and identification simple data.The result showed that the parameter identification error by BP Neural Network model in the construction control of the Bridge of South-North Water Transfer is in the in the acceptable range,which means the established BP Neural Network model is feasible for parameters identification.