Research On Static And Dynamic Performance Of CFRP Suspender Arch Bridge And Optimization Of Suspender Force

Suspender was an important force transmission component of arch bridge.Due to the sudden fracture of suspender the deck of many arch bridges at home and abroad has partially or completely collapsed,causing great loss of life and property.Carbon fiber composite reinforced polymer(CFRP)has the advantages of corrosion resistance,fatigue resistance,high strength and non-magnetic properties.Therefore,the application of CFRP material in arch bridge provides a new method to solve the suspender problem of arch bridge.This paper takes a 104m arch bridge as the engineering background,the steel suspender of the arch bridge is replaced by CFRP suspender with finite element software ANSYS.The static characteristics,dynamic characteristics,dynamic response of the suspender and suspender force optimization of the CFRP arch bridge are studied.The main contents of this paper are as follows:(1)The steel suspender of the arch bridge is replaced with CFRP suspender by three replacement principles of equal strength,equal stiffness and equal area The static characteristics of the arch bridge after replacement all meet the engineering needs.At the principle of equal strength replacement,the CFRP material is the least.Compared with the original steel suspender,the area of CFRP suspender is reduced by 20.5%,but the stiffness of CFRP suspender is only 55.9%of the original steel suspender.At the principle of equal area replacement,the stiffness of CFRP suspender is 72.3%of that of the original steel suspender.At the principle of equal stiffness replacement,the CFRP material is the most,and the area is increased by 42.3%compared with the original steel suspender.Considering the characteristics of CFRP material,the safety of structure after replacement and the economy of replacement,it is best to adopt the principle of equal strength replacement.(2)The dynamic characteristics and dynamic response of suspender of an arch bridge replaced by CFRP suspender with equal strength are analyzed by ANSYS.CFRP suspender arch bridge and steel suspender arch bridge have the same first-order natural vibration modes,and the different of the first-order natural vibration frequencies was only 0.07%.At the same load condition,the stress amplitude of the right suspender that near the position where vehicle load was applied was more than 3 times that of the corresponding left suspender.Compared with single vehicle load,the maximum increase of stress peak of CFRP suspender and steel suspender is 18.4MPa under transverse two vehicle load.Compared with transverse two vehicle load,the maximum increase of stress peak of CFRP suspender and steel suspender is 15.6MPa under transverse three vehicle load.At the same vehicle load condition,the stress peak of CFRP suspender is about 10%larger than that of steel suspender,and the maximum stress peak is not more than 20%.(3)Response surface method was used to optimize the forces of suspender of arch bridge.The response surface function between the static response of the arch bridge structure and the force of the suspender was fitted.The response values of key sections of the arch bridge optimized by response surface method are Compared with the initial value at dead load,the strain energy of the arch rib and beam was reduced by 4.88%,the bending moment of the middle span of the beam was reduced by 31.56%,and the bending moment at the top of the arch rib was increased by 57.12%,but the moment at the end of the arch rib with the most complex stress was reduced by 21.8%.The deflection of the beam at each cable position was much smaller than the initial value at the dead load,and the deflection at the mid-span position was reduced by 24.51%.