| The extradosed cable-stayed bridg has been developed rapidly at home and abroad in recent years due to its superior structural form.V-shaped extradosed cable-stayed bridge is a novel form of low tower cable-stayed bridge,which is named after its special V-shaped towers distributed along the longitudinal direction.The construction of V-shaped extradosed cable-stayed bridg adopts the form of hanging basket cantilever casting.During the whole long construction cycle,the bridge structure is very easy to be affected by various factors such as construction environment,human factors,construction technology,etc.,so that the errors accumulate during the construction process,which eventually leads to uneven bridge alignment and unsuccessful closure,and even affects the structural safety of the bridge.Especially in the form of V-shaped short towers,the structural parameter changes are more sensitive to the response of the shaped structure,which requires a higher standard of precision and safety in bridge construction.In order to guarantee the safety and reliability of the structural elements during construction,and to ensure the smooth closure of the bridge to achieve the ideal state,the construction control of V-shaped short tower cable-stayed bridges needs to be studied in depth.This paper takes the South-North Water Transfer V-shaped short tower cable-stayed bridge as the basis of the project,and studies the whole construction control work and the stress state of V-shaped cable tower,mainly completes the following work.(1)Establish the finite element rod unit model of the whole bridge,simulate each construction stage of the bridge,analyze the alignment of the main girders and the deflection of the bridge towers in each construction stage,analyze the stress changes of the important control sections in the whole construction stage,and provide theoretical data support for the field construction control work;establish the solid unit model of the bridge 0# block,analyze the stress state of the 0# block in the whole construction stage,and ensure the safety of the main girders 0# block under the shear hysteresis effect.(2)This paper proposes the setting method of the main girder elevation and the tensioning control method of the single cable of the V-shaped short tower cable-stayed bridge,and introduces in detail the field control scheme and monitoring results of the background bridge main girder alignment,stress,tower deflection and the completed bridge cable force,focusing on the analysis of the causes of the errors between the measured and theoretical values.(3)A detailed sensitivity analysis of each member of the V-shaped short tower cable-stayed bridge was carried out,and the concept of structural sensitivity factor was introduced,and the sensitivity level of each member of the V-shaped short tower cable-stayed bridge was classified accordingly.The initial tension of the cable-staying and the concrete capacity of the main girder have the most obvious influence on the structural response of the V-shaped short tower cable-stayed bridge.(4)Based on the parameter sensitivity analysis,a parameter identification model for the construction control process of the V-shaped short tower cable-stayed bridge was established based on the least squares method,and the parameter identification results were analyzed to obtain the correction method for the parameter errors.Based on the gray prediction model,the gray theory GM(1,1)model for construction control of V-shaped short tower cable-stayed bridge was established,the practical significance of the prediction results in the specific construction process was analyzed,and the active control method of construction control was derived.(5)The spatial stress distribution law of V-shaped towers under the most unfavorable load of the whole bridge is studied.The analysis shows that the overall stress state of the V-shaped tower is good,and the concrete is mainly under compression;the bottom hole of the V-shaped tower is subjected to higher transverse positive stress,and additional reinforcement network should be installed at the bottom for reinforcement;while the top hole is subjected to higher vertical positive stress,and the radius of the saddle turning area of the top hole should be increased to prevent the stress overload in the local concrete area. |
