Fatigue Damage Analysis Of Main Cable And Sling Of Suspension Bridge Based On Heavy Cargo Transportation

With the rapid development of China’s economy,industry and energy,more and more large-scale engineering facilities related to machinery,electricity,energy and chemical industry have been put into construction,and more and more high-value,heavy,large-size and non removable large objects such as transformers,wind turbine blades and reactors have been transported,which has brought great challenges to the normal use and safe operation of highway bridges in China.Based on the previous research results,this paper studies the dynamic response of self anchored suspension bridge under the load of heavy cargo transportation vehicles and the fatigue damage effect of main cable and sling.The main work and results are as follows:(1)Based on The Principle of Total Potential Energy with Stationary Value in Elastic System Dynamics and finite element method,the motion equations of three-dimensional n-axis flat car and bridge are derived,which are connected through the coordination relationship between force and displacement,and the vehicle-bridge coupling dynamic equations are formed.(2)Using the accurate balance analysis function of suspension bridge in MIDAS/Civil bridge finite element calculation software,the initial balance state of suspension bridge is determined,and the coordinates of each node of main cable and the initial stress of cable are extracted.(3)The finite element model of bridge and vehicle is established by using ANSYS software,and the displacement coupling between bridge deck and wheel contact point is realized by using the constraint equation command(CE command)in ANSYS.Based on the pavement power spectrum function defined in the national standard(GB/T 7031-2005),using the trigonometric series method and MATLAB software for programming and calculation,the grade a ～ d pavement irregularity samples are obtained.By defining the form of table array,the irregularity value of pavement samples is read into ANSYS.(4)Using the transient analysis function of ANSYS software,the dynamic response of vehicle-bridge coupling system is solved,and the effects of vehicle speed,vehicle weight and road roughness on the dynamic response of suspension bridge,such as mid span node vertical displacement,mid span node vertical acceleration,tower top longitudinal displacement,Main Cable axial force and sling axial force,are studied.(5)The fatigue damage analysis model of main cable and sling of suspension bridge is established.The rain flow counting method program is compiled with MATLAB software to count and count the stress time history curves of main cable and sling,and the stress spectrum of main cable and sling is obtained.The nominal stress method is used to analyze the fatigue damage of the main cable and sling of the suspension bridge under the load of heavy cargo transportation vehicles,and the effects of the speed and weight of heavy cargo transportation vehicles on the fatigue damage of the main cable and sling are studied.(6)By introducing the concept of standard fatigue loading vehicle,the fatigue life of main cable and sling of suspension bridge under various fatigue vehicle loads is estimated by using the nominal stress method.The effects of annual transportation frequency,vehicle speed and vehicle weight of heavy cargo transportation vehicles on the fatigue life of main cable and sling are studied.Based on this,the safety evaluation method of heavy cargo transportation vehicles passing through self anchored suspension bridge is given.