Analysis Of Dynamic Characteristics And Seismic Response Of A Railway Extradosed Cable-stayed Bridge During Construction

In recent years,with the development of China's economy and advances in technology,the construction and development of bridge projects has been greatly promoted,because of the strong spanning ability of extradosed cable-stayed bridge,the mature construction technology,stable and reliable structure,has been widely used in our country's bridge construction.Our country is in the area of frequent earthquakes,along with the application of new materials and the advancement of computers,bridges are developing towards large spans,this makes the construction period of the bridges longer,and earthquakes may also be encountered during the construction period of the bridges,such as Akashi-kaikyo Bridge in the Hanshin Earthquake in Japan,the Jilu Bridge in the Chichi earthquake in Taiwan,and the Ai zhai Suspension Bridge in Jishou City,Hunan Province.In the construction stage,the degree of freedom of the structure is relatively high,the structural stability is poor,and it may be more unfavorable than in the bridging phase when subjected to an earthquake,however,the current scholars mainly study the dynamic characteristics and seismic response during the bridging phase,and few Someone studies the seismic response during the construction phase.Therefore,this paper takes the actual construction of a railway extradosed cable-stayed bridge as the engineering background,systematically studies the main construction stage and the finished bridge,the main work of this paper is as follows:1.Firstly,the paper collects the relevant data,summarizes the theory and method of anti-seismic analysis,clarify the applicable conditions and advantages and disadvantages of various theoretical methods,and makes a solid theoretical foundation for the analysis of the structure behind.2.Based on the actual construction drawings,the model of the bridge stage and the construction stage is established by Midas,the dynamic characteristics of the completed phase and each phase of the construction were analyzed to obtain the structural vibration mode and frequency variation.The effects of unbalanced loads and the height of the pier on the natural vibration characteristics of the maximum cantilever stage were studied.3.The response spectrum analysis of each construction stage and the finished bridge is carried out to study the variation law of internal force and displacement of each control section with the construction progress,and the seismic response of the construction phase is contrasted with the seismic response of the bridge stage,to find out the most unfavorable construction stage of the Control Section earthquake response.The direction of action and combination of the earthquakes taken into account in the analysis shows that the direction of action of the earthquake has a great influence on the seismic response of the structure.4.Three seismic waves are artificially fitted according to site conditions,analyzing the time-history of each construction stage and the status of the bridge,selecting the maximum value of the internal force and displacement response at the control section of each of the three waves in the construction phase and comparing the results of the response spectrum analysis,and the most unfavorable construction stage of earthquake response is found.5.The measures of installing TMD system in the most unfavorable construction stage show that the displacement and internal force of the structure can be effectively controlled after the TMD system is installed.