The Dynamic Response And Fatigue Effect Of The Ancient Timber Structure Under Traffic Excitation

Chinese ancient architecture has a unique historical and artistic value,in recent years,with a large number of infrastructure construction,the harm of ground vibration caused by traffic excitation to the building structure is becoming more and more serious,this kind of micro vibration is not as strong as earthquakes,but it is long-time and repeated action,when the structure’s dynamic stress is large,it may cause fatigue damage to the building structure.Therefore,it is of great significance to research the dynamic response law and the effect of vibration fatigue of ancient buildings on the isolation vibration and safety assessment of existing ancient buildings.Based on the domestic and foreign current research about the impact of traffic incentives and vibration fatigue on the building structure,this paper takes Xi’an bell tower as an example,firstly,the dynamic response model and response law of bell tower structure under micro vibration are studied.Secondly,the dynamic response of road traffic to Xi’an bell tower is discussed and the safety assessment is carried out.Finally,the fatigue life of the bell tower structure under random vibration excitation is estimated and analyzed by amplitude probability density method.Through the shaking table test and finite element analysis,the response of the layers of the ancient wooden structure is gradually increasing under the action of micro vibration,this means that the vibration from the ground is amplified.The structural deformation is an inverted triangular shape on the whole.Established the Xi’an bell tower finite element model of wood structure-high platform-ring foundation,the vibration response of the ring lane load to the structure is analyzed,the law of propagation and attenuation of ground vibration is obtained,the most unfavorable conditions of single and double line driving,different speed and different vehicle arrangement are got,finally,use the relevant code to assess the dynamic response of the most unfavorable conditions.In this paper,a period of acceleration history curve is transformed into an acceleration power density spectrum,and the stress response cloud image of the structure is obtained by inputting the excitation at the column bottom of the finite element model.It is found that the stress response of the lower part of the bell tower is larger than that of the second layer,and the stress at the beam and column joints is larger than that in the middle of beam,The maximum stress appears at the beam end of the corner beam-column joint.Finally,according to the fatigue properties of the material,the vibration fatigue life at the dangerous point is estimated by the amplitude probability density method and the linear damage cumulative theory.