Study On Vibration Control Of Pedestrian Suspension Bridge

With the rapid development of social economy and tourism,3D pedestrian glass bridges have been built in various scenic spots in China to attract tourists and promote the rapid development of local tourism.Footbridges often have the characteristics of long span and softness,especially the suspension bridge with the largest crossing capacity,its natural frequency and damping are becoming smaller and smaller.When the natural vibration frequency of footbridge is between 1.25～2.3Hz,it is easy to cause resonance of footbridge,which may cause panic to pedestrians or structural safety problems.Therefore,it is of great practical significance to carry out the research on Vibration Comfort Evaluation and vibration reduction control of pedestrian suspension bridge under pedestrian load in this paper.In this paper,by establishing the finite element model of a pedestrian suspension bridge in a scenic spot,the advantages and disadvantages of pedestrian load modes under different codes are compared and studied,so as to provide reference for the dynamic response calculation of pedestrian bridge;Then,in order to meet the comfort requirements of the code,TMD(tuned mass damper)vibration control method is introduced to analyze the vibration control of pedestrian suspension bridge.Based on the sensitivity analysis method,the parameters of MTMD(multiple tuned mass damper)are optimized.The main research work and conclusions are as follows:(1)The finite element model of a pedestrian glass suspension footbridge in a scenic spot is established.Through the analysis of natural vibration characteristics,it is found that the multi-level natural vibration frequencies are within the pedestrian walking range,which is prone to pedestrian bridge resonance.Therefore,it is verified that the long-span suspension bridge is prone to affect the comfort of pedestrians.(2)The pedestrian load models and comfort standards under the four specifications are summarized and compared,and the vibration response with peak acceleration as the control index is obtained through simulation.It is found that the overall structural response under ISO specification is larger than that of other specifications,and there are many cases of dissatisfaction with comfort requirements.Therefore,ISO specification is more stringent,It is suggested that the code should be selected for study when considering the vibration control of the bridge.(3)Aiming at the vibration acceleration overrun problem of footbridge,MTMD parameters are optimized based on sensitivity analysis method.On the basis of summarizing the principle of TMD and MTMD,through the finite element simulation research,it is verified that TMD is more effective for structural vibration control.However,due to the detuning effect of TMD,"negative effect" will appear in some parts of the structure.In order to improve the robustness of MTMD,a method based on sensitivity analysis is proposed to optimize MTMD parameters,including total mass ratio,bandwidth,center frequency ratio and TMD number.The results show that the optimal total mass ratio is 3%,the optimal bandwidth is 0.15,the optimal center frequency ratio is 1,and the optimal TMD number is 6.By comparing with the traditional MTMD parameter optimization model,it is verified that the MTMD optimization under parameter sensitivity method is feasible.