Construction Control Of Three-tower Hybrid Cable-stayed Bridge And Research On Mechanical Property Of The Steel-concrete Composite Segment

Hybrid girder cable-stayed Bridges are widely used in long-span bridge engineering because of their good structural performance,reasonable stress,strong span ability and beautiful appearance.Hybrid girder cable-stayed bridge structure has complex stress,complex construction procedures,and many factors that affect the state of the structure,so the construction control has become an indispensable part of the process of bridge construction,and it is particularly necessary to carry out parameter sensitivity analysis on the bridge structure.As the key section of the transition between steel box girder and concrete box girder,the steel-concrete composite segment is responsible for ensuring the transition of force,transfer stiffness between the main girder and the smooth continuous transition of the main girder.Its structure and force are very complex,the stress is directly related to the safety performance of the structure,so it is necessary to analyze the force of the steel-concrete composite segment.This paper takes Linyu Yangtze River Bridge No.6 as the research background.The main research contents and results are as follows:(1)This paper introduces the development of steel-concrete cable-stayed bridge,and expounds the related basic theory of construction control of cable-stayed bridge,including control target,work content,control method,influence factors and so on;(2)Based on the finite element model of the whole bridge,the stress of the steel-concrete joint section in the construction stage and the operation stage of the completed bridge is analyzed from the perspective of the whole force,and the internal force data of the maximum axial force,maximum positive bending moment and maximum negative bending moment are extracted.The boundary load is provided for the fine model of local steel-concrete joint section,and according to the calculation results of the whole bridge,to design the monitoring scheme;(3)Midas Civil was used to build the whole bridge model of Linyu Yangtze River No.6 Bridge.There are many factors influencing the structure into the state of the bridge,this paper selects girder self-respect,the stay cables of the tension,temporary load.girder stiffness,suspension stiffness and temperature,analysis the change of these factors on the structural conditions of linear,girder cable-stayed cable force,girder stress and displacement of cable tower.Through analysis and research.When the parameter changes separately,for bridged lines,the sensitive factor is the modulus of elasticity of cable,the self-weight and cable force;For bridge cable force,the sensitive factor is the self-weight and the modulus of elasticity of cable;For the deflection of the bridge tower,the sensitive factor is the self-weight,the modulus of elasticity of cable and cable tension force;When the parameter combination changes,bridge response of the combination of main beam weight and system temperature,weight and stiffness of main beam,initial tension and elastic modulus of cable has a large bridge response;(4)The finite element calculation model of steel-concrete joint section was established by Midas/FEA.The detailed simulation analysis of the structure is carried out,and the most unfavorable load condition extracted is added.The stress distribution and mechanical characteristics of steel-concrete joint section under different load conditions are discussed:For the stress variation of the whole steel-concrete joint section,the stress under the maximum positive moment condition is larger than that under the maximum longitudinal axial force condition and the maximum negative moment condition.The slab stress of steel box girder gradually decreases from the side of steel box girder to the side of concrete girder,The variation range of stress in the transition from the pressure plate to the steel-concrete joint section is relatively large,The reason is that the stress redistribution of the pressure plate.the internal force from the side of the steel box girder through the pressure plate part of the internal force is transferred to the concrete in the steel-concrete joint section.The other part is transferred to the concrete beam through the stiffening ribs of the top and bottom of the steel lattice cell web.