The Influence Of Temperature On The Self Vibration Characteristics Of CFST Deck Arch Bridge And Seismic Response Analysis

With the construction of concrete filled steel tube arch bridge,its self-vibration performance and seismic performance have become an important research direction.The dynamic performance of the bridge built in the area with large temperature difference shows a significant correlation of temperature.For the deck type CFST arch bridge,the influence of environment temperature on its self-vibration characteristics and seismic response has its own characteristics.Based on the theory of structural dynamics and the finite element method,the dynamic performance of a main span 160 m deck type CFST arch bridge under the influence of ambient temperature is analyzed in this essay.The main conclusions are as follows:1.The influence of environment temperature on the self-vibration frequency of bridge structure is caused by the temperature-dependent properties of materials,structural geometry,bearing stiffness,the boundary types and the initial temperature force of structures.The derivation based on the theory of structural dynamics shows that the temperature-dependent properties of materials and initial internal force are the main reasons for the variation of the self-vibration frequency of the simply supported beam with temperature,and the influence of the geometric size change is very small.2.The dynamic analysis of the finite element software Midas/Civil shows that the environment temperature has a negative correlation with the self-vibration frequency of the structure.The temperature-dependent properties of the material properties and the support stiffness is the main reason for the change of the self-vibration frequency of the deck type CFST arch bridge.The effect of low temperature is greater than the effect of high temperature.Taking 15? as the reference temperature,the transverse fundamental frequency increases by 23% at-45? and the vertical fundamental frequency increases by 31% when the temperaturedependent properties of all factors are taken into consideration.3.Considering the temperature-dependent properties of materials,the natural frequency is most affected by the elastic modulus of asphalt concrete,followed by the elastic modulus of C50 concrete.The temperature-dependent properties of Q345 steel has little influence on the natural frequency.The increase of the lateral stiffness of the structure is greater than the vertical stiffness at low temperature,so the vertical vibration mode is ahead of time and the lateral vibration mode is lagging behind.4.The influence of the stiffness of the low temperature bearing on the frequency is more remarkable than high temperature.The influence of the shear stiffness on the self-vibration frequency is greater than that of the compressive stiffness.The sensitivity of the vertical fundamental frequency of the structure to the change of the support stiffness is greater than that of the lateral fundamental frequency.Whether the support stiffness is increased by ice or the failure of the expansion joint,it will have a great effect on the frequency and mode of the structure.5.The results of seismic response analysis show that the influence of environment temperature on the longitudinal and transverse seismic responses of arch rib is significant,and it has little effect on vertical seismic response and can be ignored.Both the transverse and longitudinal seismic responses of the arch ribs and the main girder of the bridge are increased at low temperatures.The axial force of the arch rib is increased by 20% in the longitudinal seismic response at-45?.The axial force of the transverse seismic response of the bridge deck is 14.83 times higher than that of the original one at-45?.Therefore,the increase in the longitudinal seismic response of the arch foot and the increase of the lateral seismic response of the bridge deck should be paid attention to by the designer.