Research on the Long-wave Irregularities Limit of Long-span Cable-stayed Bridge under Temperature
Research purposes:In order to study the deformation of long-span cable-stayed bridge under the action of temperature and the influence of long-wave irregularities on train response,Quanzhou Bay steel-concrete composite beam cable-stayed bridge which crosses sea was taken as the research object,the temperature sensors were arranged on the beam section to monitor the temperature changes of the beam,then the ANSYS software was used to analyze the vertical deformation of the beam when the cable-stayed bridge was under the action of measured temperature,which was added to the original irregularities.The vehicle-bridge coupled model considering the long-wave irregularities was established based on the principle of constant total potential energy of elastic system dynamics to study the influence of long-wave irregularities on train dynamic response,the adaptability evaluation by chord measurement method,and the corresponding limit value under the limit condition of temperature deformation.Research conclusions:(1)The temperature monitoring system collects the temperature data for one year.After decomposing it into uniform temperature and linear temperature difference,the corresponding temperature variation ranges are[5.82 ℃,37.51 ℃]and[2.36 ℃,29.94 ℃]respectively.The maximum vertical displacement in the middle of the main span of the beam is 28.6 mm and the minimum vertical displacement is 14.1 mm.(2)Compared with the vehicle-bridge coupled vibration model without considering the temperature effect,the wheel load reduction rate,vertical acceleration and vertical comfort index of the train calculated by the model considering the long-wave irregularities caused by the temperature effect increase to a certain extent,and the increase of vertical acceleration is the most obvious.(3)After considering the influence of bridge dynamic displacement caused by train operation,the 60 m chord midpoint chord measurement method can still well reflect the train vibration response,and has the best correlation with the vertical acceleration response of the vehicle body.(4)Through the analysis and verification of the calculation results of the irregularities of 60 m chord,it is obvious that the dangerous position of passing vehicles when driving on double lines is near the bridge tower.(5)Under the limit condition of temperature deformation,the vertical acceleration of the train reaches the specification limit,and the corresponding 60 m chord vector limit is 7.22 mm.(6)The research results can provide reference for the determination of the limit and the selection of evaluation methods about long-wave irregularities for long-span cable-stayed bridges.
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