Study Of Vibration Response For Large-span Floors Considering Pedestrains-structure Interaction

With the use of high strength lightweight materials,many lightweight floor systems and large-span floor structures have been widely used.Because of the low vertical self-vibration frequency and relatively small mass and damping of this floor system,it is easy to have the pedestrian-induced vibration serviceability problems.The interaction between pedestrians and structures is one of the key problems to accurately predict the pedestrian-induced vibration response of structure.The study of simplified pedestrian model parameters is a key factor in understanding how this interaction works,and it provides some guidance for the the vibration control design of the structure.The main concerns and conclusions are as follows:1.Study on the parameters of simplified pedestrian model.A one-man walking test was performed on the low frequency test floor with 25 people walking on defferent step frequencies.Based on the single-degree-of-freedom Mass-Spring-Damper(MSD)model of pedestrian,the model of the two-degree-of-freedom pedestrian-structure coupling system is established.Natrual frequency and damping ratio of test floor is obtained by modal test before and after one pedestrian walking on it,then generate them into the equation to get fundamental frequency and damping ratio of the pedestrian MSD model.The results show that: when the pacing frequency is 1.5Hz,the pedestrian MSD model frequency is about 2.17 Hz,and the damping ratio is 27.77%;when the pacing frequency is 1.7Hz,the pedestrian MSD model frequency is about 2.14 Hz,and the damping ratio is 29.37%;when the pacing frequency is 1.9Hz,the pedestrian MSD model frequency is about 2.11 Hz,and the damping ratio is 30.74%;when the pacing frequency is 2.1Hz,the pedestrian MSD model frequency is about 2.08 Hz,and the damping ratio is 32.30%.2.Analysis of the influence of pedestrian-structure interaction on structure dynamic characteristics is carried out.The model of the two-degree-of-freedom pedestrian-structure coupling system is established and dynamic characteristics of the structure is analyzed in the field of pedestrian-structure mass ratio,frequency ratio.3.The influence of structure vibration on HSI effect is analyzed.The parameter identification results of pedestrian MSD model under different excitation frequencies are obtained by experiment.It is found that pedestrian is more sensitive to low frequency vibration and less to high-frequency vibration.The parameter identification results of pedestrian MSD model under different vibration level conditions are also obtained by experiment.It is found that the pedestrian frequency decreases with the increasing of the structure vibration level,while the pedestrian damping ratio increases gradually with the increasing of the structure vibration level.4.Based on the one-man walking test,the vibration response and the TMD vibration control of the test floor considering pedestrian-structure interaction are analyzed.The acceleration response data before and after the vibration control of the floor is obtained through the one-man walking test.It is found that the vibration reduction rate of the test floor is about 40% to 50%.A single walking test is carried out on the vibrating floor under different working conditions by using the exciter to apply fixed excitation to the test floor.It is found that the coupling effect of the pedestrian structure is beneficial to the floor vibration control.