Study On The Influence Of Mean Wind And Temperature On The Suspension Bridge Frequency

With the development of bridge technology,more and more large-span bridges have been built,especially large-span suspension bridges.However,as a large-span flexible structure,the suspension bridge is more and more obvious by the influence of environmental factors.Analysis of the dynamic characteristics of a bridge is an essential step in the wind resistance,anti-seismic,and other dynamic loads of bridges and the detection of structural damage.This paper relies on a certain mountain area of steel truss suspension bridge as the object,using the ANSYS finite element software to study the mean wind and temperature influence on the suspension bridges frequency,and provide reference for the design and construction of similar long-span suspension bridges.The research work of this paper mainly includes the following contents:1.The model of the suspension bridge was established by finite element software and numerical analysis was carried out.According to the finite element software analysis of the suspension bridge's dynamic characteristics,as well as the use of Computational Fluid Dynamics(CFD)technology,the aerodynamic parameters of this bridge section is determined.The static wind load and aerodynamic stiffness of different wind speeds are applied to the suspension bridge.Study the variation of its modal frequency.It is found that the static wind load and the aerodynamic stiffness have a greater influence on the modal frequency of the suspension bridge with the increase of wind speed.2.As a large-span flexible structural system,the suspension bridge studies the influence of the static wind on the frequency of the suspension bridge.The variation law of the influence of static wind load on the frequency of suspension bridges under different wind speeds is analyzed.The research shows that the frequency of the suspension bridge under different static wind loads are small.The aerodynamic stiffness matrix is added to the main beam of the suspension bridge to study the influence of aerodynamic stiffness on the frequency of the suspension bridge.The research shows that the frequency of the suspension bridge is reduced after increasing the aerodynamic stiffness.The static wind load and aerodynamic stiffness of different wind speeds are applied to the suspension bridge to study the variation law of the frequency.At higher wind speeds,the influence of aerodynamic stiffness on the natural vibration frequency of the suspension bridge cannot be ignored.3.Study the effect of ambient temperature on the frequency of bridge structures.The effect of temperature,the elastic modulus of the material,temperature change structure internal force and elastic modulus work together,and the influence of the temperature gradient on the frequency of the suspension bridge are studied.With the change of elastic modulus,the frequency of suspension bridge decreases with the decrease of elastic modulus,but the rate of change is larger.Under the joint action of temperature and elastic modulus,the frequency of the suspension bridge decreases with the increase of temperature,and the interaction of the two has a great influence on the modal frequency variation of the suspension bridge.Finally,different temperature effects are applied to the equivalent main beam of the suspension bridge to simulate the influence of temperature gradient on the frequency of the suspension bridge.The research shows that the temperature gradient has little effect on the frequency of the suspension bridge.