Research On Key Technical Problems In Construction Control Of Extradosed Cable-stayed Bridge And Analysis Of Dynamic Characteristics

With the continuous development of China’s transportation industry,more and more bridge structures have emerged.The extradosed cable-stayed bridges,as a representative,not only improve the utilization efficiency and spanning ability of the main girder,but also increase the allowable stress of the stay cable,so it have been widely used in bridge engineering fields at home and abroad.The on-site construction of an extradosed cable-stayed bridge is often accompanied by a long process.In this process,due to the organizational structure,technical conditions and internal and external factors of the construction site,the construction error will continue to accumulate during the construction process,affecting the construction process and affecting the structural stress characteristics.In order to reduce or eliminate these construction errors as much as possible,and ensure that the line shape and stress state of the structure after the completion of the bridge are in line with the design status,an in-depth study of the construction control work is required.This paper takes the Yuxi River Bridge as the foundation of the project,and studies the construction control work and seismic performance in the construction process,mainly completing the following aspects of work.1.Establish a full-bridge finite element model to simulate all the construction stages of the full-bridge,calculate and analyze the stress state and displacement deformation of each component of the bridge under various conditions of construction,and provide a theoretical basis for on-site monitoring;bridge structure in the completed state Check the force state under each sub-item loading;establish a solid model and perform detailed analysis of the 0# block of the bridge structure under each construction phase condition.2.According to the construction control plan for the Yuxi River Bridge,this paper describes in detail the control methods and control results of the alignment,stress,tower deviation and cable force of the Yuxi River Bridge.Through the construction control work,the structural line shape meets the requirements,and the stress variation test result conforms to the change rule,and the bridge structure meets the force requirement.3.The detailed sensitivity analysis of the members of the extradosed cable-stayed bridge is carried out.For the cable-stayed bridge with low tower,the influence of the bulk density of the girder is the most significant;the influence of the temperature load on the structural stress is the most significant.4.This paper studies the application of least square method and BP neural network method in construction control parameter identification.The least square method can meet the single parameter and double parameter identification in the construction control process.The BP neural network method is used for single parameter.The two parameters can be accurately identified.However,due to the limitations of data acquisition in construction control work,the training sample is insufficient.The BP neural network is not ideal for recognizing three different parameters.5.This paper studies the application of GM(1,1),SCGM(1,1),and BP neural networks in the construction control work.The GM(1,1)gray prediction model can use fewer Group data makes a more accurate prediction of the subsequent state of the structure.However,the accuracy of the GM(1,1)model gradually decreases as the structure state changes continuously with time.The accuracy of the SCGM(1,1)metabolic model prediction is higher and the applicability is stronger.BP neural network prediction model It also has a higher prediction accuracy,but it requires a large number of learning samples,and its applicability is not strong.6.In this paper,a series of analysis of the seismic performance of the Yuxi River Bridge is carried out,and the analysis shows that the extradosed cable-stayed bridge exhibits good seismic performance under the action of seismic load,and meets the specific requirements under the E1,E2 earthquake effect.The most unfavorable position of the cable-stayed bridge under the earthquake load is the main pier bottom and the bottom of the main tower.The compressible and shear bearing capacity of the main pier bottom under E2 earthquake load are all close to the limit.