Research On Joint Effect Of Temperature And Wind Speed And Deformation Characteristics Of Coastal High-speed Railway Cable-stayed Bridge

In recent years,China’s high-speed railway sector has attained swift advancement and long-span cable-stayed bridges have emerged as a crucial component of the country’s high-speed railway system.Apart from the train load,temperature and wind loads hold paramount significance as variable loads for long-span cable-stayed bridges.With towering bridge piers and closely placed cables,they are exceedingly responsive to wind loads,whereas their ultra-long beams make them highly receptive to temperature fluctuations.Currently,research on the annual and daily periodic variations of structural temperature,numerical representation of temperature time histories for various components of cable-stayed bridges,and the temperature difference within structural systems is scarce.Furthermore,there remains inadequate calculation models,deformation characteristics,and structural safety assessments for the combined effects of wind and temperature.Hence,to guarantee the structural integrity of long-span cable-stayed bridges for high-speed railways and secure the safe operation of high-speed trains,it is crucial to establish a comprehensive model that takes into account the combined influence of wind and temperature.Furthermore,it is imperative to conduct research on the combined effects of temperature and wind under different conditions of control,and accurately predict the deformation characteristics of the bridge to ensure the long-term functionality of high-speed railways.With this objective in mind,the present paper focuses on the Quanzhou Bay Cross-Sea Bridge and conducts the following studies:Establishing a system for long-term monitoring of the structural temperature field during the construction phase,in order to collect extensive monitoring data on the structural temperature and bridge deformation at critical locations of the long-span cable-stayed bridge,is imperative.This data collection will enable one to obtain the uniform temperature variation laws on an annual and daily basis,and spatial distribution laws of each component of the cable-stayed bridge,including the bridge tower,cable,and composite beam.Furthermore,it is essential to propose a more comprehensive method for establishing the temperature distribution pattern and time-varying characteristics of the structure.By doing so,one can derive the long-term and short-term fluctuation curves of the structural temperature and obtain the representative value of the temperature load of the structure under specific recurrence periods through extreme value analysis.A meticulous examination was performed on the thermal distribution characteristics of the structural system of the bridge,and a method for computing the temperature differentials among the various components was postulated.Utilizing a comprehensive analysis of the gathered temperature information of the composite beam,cable,and tower,a two-dimensional maximum entropy model was utilized to construct a joint probability distribution model of the temperature differences between the beam and tower,and the temperature differences between the beam and cable.This constitutes a valuable reference for the temperature differential model in the planning and development of the cross-sea cable-stayed bridge.Drawing upon long-term temperature and wind speed data at the bridge site,an exhaustive analysis was undertaken to investigate the spatio-temporal properties of the wind and temperature fields in the primary structural system of the bridge.Accordingly,a mathematical model,which accurately corresponds to the measured temperature and wind data,was formulated.Moreover,a two-dimensional probability distribution function was proposed to account for the combined effect of temperature load and wind load under various probability guarantees in the offshore environment,along with the combination coefficients of various directional loads.A three-dimensional finite element model was created for the steel-concrete composite girder cable-stayed bridge at the Quanzhou Bay Cross-Sea Bridge.The deformation response of the bridge was calculated and compared to the measured deformation data,based on the component temperature difference model and the temperature-wind speed joint action model.The deformation response of the cable-stayed bridge was analyzed using the full-bridge model,and the effect of each temperature component on the bridge deformation was ranked.Additionally,a method was proposed to predict the time-varying characteristics of the cable-stayed bridge deformation under the joint action of temperature and wind speed.