Modal Parameter Identification And Field Measurement Of Mountain Wind Characteristics At Taiyuan South Station

With the development of social economy and the need of urban construction,more and more buildings with complex structure and large span are built.The health status of these buildings during service has attracted wide attention.The real-time monitoring data of the structure can be obtained by field measurement,and the health status of the structure can be evaluated by analyzing the data of wind speed and acceleration response.Based on the health monitoring platform of Taiyuan South Railway Station,the wind time history data of strong wind and non-stationary wind and the acceleration response under multi-condition excitation are obtained,and the above contents are studied respectively.Based on the wind time history data collected from two measuring points in Taiyuan South Station,the average wind speed,wind direction and fluctuating wind power spectrum of strong wind in Taiyuan South Station in spring and summer are studied.The variation of turbulence intensity,turbulence integral scale and gust factor with average wind speed are investigated,and the wind characteristics in spring and summer are compared.Based on the two kinds of non-stationary wind time-history data collected by Taiyuan South Station,the measured power spectral density of fluctuating wind speed was obtained by processing the non-stationary wind time-history data with the stationary wind as the control group.Hilbert spectrum and marginal spectrum of fluctuating wind time history are obtained by HHT method,and time-frequency analysis of non-stationary wind time history is carried out by EPSD estimation method based on Priestley.Based on the health monitoring system of Taiyuan South Railway Station,the acceleration responses under environmental excitation,train working condition excitation,crowd excitation and construction excitation are analyzed.Especially,the working conditions of the first,second and third groups of trains entering and leaving the station and the train not stopping are studied in detail.The acceleration responses under deterministic excitation are mainly concentrated in several frequency points related to the frequency of train load axle load（fv1,fv2,fv3）and the natural vibration frequency of the station.The peak acceleration response under each working condition is less than the limit value specified in the specification.The equivalent peak acceleration（ESPA）curve can better reflect the comfort level of the structure of Taiyuan South Railway Station.Next,identify the modal parameters of the vibration response of the dense frequency structure,and perform modal decomposition of the acceleration response through three time domain methods: the feature realization algorithm（NEx T-ERA）,the random subspace method（SSI）and the random decrement method（RDT）And parameter identification.For the largespan structure of Taiyuan South Railway Station,the vibration mode is low-frequency and dense.Because SSI and NEx T-ERA are far superior to RDT in terms of universality,accuracy and calculation efficiency of identifying modal parameters,SSI is used.The modal parameters can be well identified with the NEx T-ERA method,and the amplitude correlation of the modal parameters can be obtained by using the RDT method.Finally,summarize the research content of this article and clarify the next research direction.