Research On Human-Induced Vibration Response And Vibration Control Of Long-Span Floor In High-Speed Railway Waiting Hall

With the application of the new type of structural system and lightweight materials, more and more long-span engineering structures with flexibility and low damping have appeared in construction. Correspondingly, the crowd-induced load may lead to the excessive vibration which compromises pedestrians’vibration comfort. The crowd walking load is one of the important factors affecting large-span floor vibration comfort, studying the crowd walking load model and its effects can laying a foundation for long-span floor dynamic design and vibration control. So this dissertation focuses on human-induced vibration and it’s control of long-span floors on the high-speed waiting room which is more flexible than conventional buildings. And the analyze theory, numerical simulation and experimental methods of them are systematically investigated with respect to three aspects, i.e., analysis model of crowd walking load and analysis methods of crowd-induced vibration resonance of long-span floors, analysis methods of structural control system, optimal and practical design methods of control system under crowd-induced loads. The main contents and achievements in this dissertation are as follows:1. The dynamic characteristics and analysis model of walking load are systematically investigated based on experiments.10866 reliable records of single footfall curves are statistically analyzed. Based on the experimental results, the variation range and probability distribution of several key parameters, such as step frequency, stride length and correct time for two-foot-reclosing, are studied. A Fourier series model is then proposed to describe the single footfall load curve whose first three orders of dynamic load factors and phase angles are determined by the step frequency. According to the 11465 groups of step frequency and 3103 records of phase angles measured from the five high-speed rail stations, the characteristic parameters statistical distribution regularity of crowd walking in waiting room are deduced. Based on the single person walking load model and the statistical results of crowd walking, a new method to model stochastic crowd-induced loads is proposed considering the random distribution of the people’walking step frequency and phase angle. The results indicate that walking step frequency show a normal distribution with a mean pacing rate 1.8811 Hz and standard deviation of 0.1766 Hz in high-speed rail waiting room, phase angle meet a uniform distribution from 0 to 2k interval, the crowd walking load simulation can accurately simulate high-speed rail waiting room’crowd-induced excitation.2. The human-induced vibration responses of long-span floor structure under pedestrian load excitation are systematically studied. At first, according to the actual crowd distribution characteristics of the high-speed rail waiting room, two kinds of analysis models of ordered arrangement crowd walking load and random distribution crowd walking load are proposed. Secondly, the vibration equations of large-span floor structure under walking-crowd excitation are analyzed and the crowd-induced vibration response of long-span floor structure of the high-speed rail waiting room. And then, the 7.7 m* 4.7 m steel-concrete composite floor slab structural model is designed and human-induced vibration experiments of under different number of subjects walking excitation are conducted on this model strucuture. At last, the results are compares with experimental study and theoretical analysis. The results show that vibration acceleration response of long-span floor structure under ordered arrangement and fixed step frequency walking-crowd excitation is more prominent compared to the stochastic crowd walking load. The established human-induced vibration analysis method can accurately predict the vibration response of large-span floor structure under walking-crowd excitation.3. Human-structure dynamic interaction impacts on structural dynamic characteristics of long-span floor and the pedestrian load are systematically researched. Based on the structural modal parameter identification test on model with or without 80 different of human occupant, natural frequency and its damping ratio of equivalent model for human body is established. Then, based on the measured structural fundamental frequency and damping ratio of test model with different number of human occupants, influence regularities of human-structure dynamic interaction on dynamic properties of structure are studied. Futher more, the single footfall forces of seven different subjects respectively on test platform and the approximate rigid ground are tested. Human-structure dynamic interaction on the influence of pedestrian load is investigated. The results reveal that the problem of human-structure dynamic interaction need to be considered when the dynamic responses of structure under crowd-induced excitation are studied.4. The human-induced vibration responses of long-span floor structure under crowd walking excitation considering human-structure dynamic interaction are systematically studied. At first, human-induced vibration test of model structure under crowd walking excitation with different step frequency when there are different number of human occupants. Secondly, Human-induced vibration dynamic equations of long-span floor considering human-structure dynamic interaction are deduced based on the principle of structural dynamics and modal superposition method. And then, The human-induced vibration analysis method considering human-structure dynamic interaction of of long-span floor is proposed. The vibration acceleraton responses under walking-crowd excitation of long-span floor in South Changsha Railway Station are analyzed according to the proposed analysis method. At last, parameters analysis of human-induced vibration response of human-beam coupling system are studied and the change regularities are analyzed. The results show that human-induced vibration response of floor structure decrease in a certain degree with different number of human occupants compared to with no human occupant. The established human-induced vibration analysis method considering human-structure dynamic interaction can accurately predict the vibration response of long-span floor structure with human occupants under walking-crowd excitation.5. The design methods for human-induced vibration and it’s control of long-span floor structure are systematically studied. At first, the coupled motion equation of the human-floor-MTMD system considering human-structure dynamic interaction is deduced and the analysis method of crowd-induced vibration response is studied. Secondly, parameter analysis of coupled vibration system are researched and the control effects of TMD device for human-induced vibration response are investigated. And then, The optical design method for human-induced vibration control of long-span floor structure with MTMD system is proposed based on the principle of Genetic Algorithm and the MTMD optimum design project is investigated by making corresponding program. Furthermore, a simplified design method for human-induced vibration control of long-span floor with MTMD systems is proposed and applied to long-span floor in South Changsha Railway Station. At last, based on field measurements in high-speed rail waiting room, the vibration responses under walking-crowd excitation of long-span floor with or without MTMD are investigated. The results indicate that the proposed MTMD vibration control design method can effectively analyze and reduce the crowd-induced vibration response.