Force Performance And Optimization Analysis Of Cast-In-Situ Supports For Wide Concrete Pipes

As the concrete cast-in-place bracket has the advantages of low requirements on the use of implements and mechanical lifting equipment,high practicability,convenient construction,short set-up time,easy disassembly,and the advantages of repeated use,it can cover a large area and use various small and medium spans.Trail bridge design construction.As the span of the bridge increases,the erection of the bracket becomes more and more complicated.The number of statically definite times of the bracket structure is larger,and only the full-span bracket system cannot meet the requirements for cast-in-place construction of long-span bridges,so the berels beam column Assembled brackets came into being,and the composite system brackets are better suited to a variety of complex terrain and support height requirements.In this paper,based on the in-situ cast-in-place section of the entire north span of the Jiayu Yangtze River Bridge,a finite element model of the steel shell beleline beam-type bracket system was established based on Midas civil,and the stress characteristics of the steel pipe bezel-beam column bracket system were studied.The system research,using the calculation of the software and the calculation of the calculation of the pile foundation bearing capacity.The main research results are as follows:(1)Classification of cast-in-place concrete scaffolds,brief introduction of various construction methods and development status at home and abroad,expounding various methods for calculating scaffolds and theories related to the relative strength and stability of scaffolds,and The calculation theory of base bearing capacity is elaborated.(2)Detailed analysis of the vertical and horizontal layout of the north span of the entire Jiayu Yangtse River Bridge.The horizontal layout was established through the large-scale finite element analysis software Midas civil 2015.Three lateral single row finite element models were established for comparative optimization analysis,and the horizontal orientation of the support was determined.The optimized layout of the layout is that the eight lateral piles meet the requirements of force and meet the requirements of the most economical province.Based on the vertical layout,the vertical layout is mainly affected by the topography and geological conditions.As a result of the final optimization,a 12.75m+17m + 12.75m longitudinal deployment span is adopted across the embankment bridge,and the Bailey beam is double-layered,with the other three spans adopting standard spans of 8.5m and 9m,and the Bailey beam adopts a single-story layout..(3)Based on the optimization of vertical and horizontal layouts,the finite element software Midas civil was used to model the first span steel shell bezel and beam support on the north side of the Jiayu Yangtze River Bridge,and the loading system was used to load the support system at one time.After detailed calculation and analysis,the strength,stiffness,and overall stability of each component of the bracket meet the requirements.(4)Based on the optimization of vertical and horizontal layouts,the finite element software Midas civil is used to perform the timing process on the pier top and the in-situ cast in-situ section between the third and fourth spans of the Jiayou Yangtze River Bridge in the north of the support cast-in-situ section of the Jiayu Yangtze River Bridge.Based on the analysis of operating conditions,the stress and deformation of the steel shell beret beam column support under various working conditions were repeatedly corrected and checked,and the strength,stiffness and overall stability of the various components of the support were met.Through the two different loading methods(3)and(4),the steel shell bezel supports can meet the force requirements,and the method of one-time loading of the load partition is convenient and quick to model,but the method and construction of the partial loading are analyzed according to the time schedule.The specific process is consistent and meets the process control requirements in the engineering quality control.Both modeling loading methods can provide reference value for the future in-situ concrete support checking.(5)Using Midas civil to model 21#to 24#of the third span of the Jiayu River Bridge,use the Midas FEA to build a 2x9m box-girder solid model to analyze the impact of the lateral prestress on the support,and Impacts made specific targeted recommendations.(6)Based on the calculation of the reaction force of Midas civil above,the bearing capacity of the pile foundation at the second span(span of 85m)across the bridge of the Jiayu Yangtze River Bridge was compared and calculated by hand calculation and calculation.The software calculated by Lizheng is slightly larger than the calculated value by hand.Both hand calculations and computer calculations show that the bearing capacity of each pile in each site is obviously greater than its corresponding counterforce,so the bearing capacity of the friction pile meets the specification requirements.(7)Based on the geological conditions of the northern boundary of the Jiayu Yangtse River Bridge,the data of the bearing capacity of the above pile foundation was extracted,and the data was subjected to regression analysis using the principle of least squares method.The data was fitted to the specific geological conditions at the embankment bridge.When the diameter of pile foundation is fixed,the bearing capacity of pile foundation approximates the linear relationship with the depth of pile foundation.The modified curve is obtained by correcting the fitting curve from the angle of safety.The engineering significance is that the position of the pile foundation slightly changes,and its geological condition Under the same circumstances,according to the size of the pile foundation reaction force,the depth of the pile foundation can be judged roughly,and it is hoped that it can provide reference for similar pile foundation bearing capacity calculation.