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Walking crowd-induced lateral vibrations on slender structures have attracted considerable attention. The improper vibration of a structure adversely affects human comfort. To explore the effects of crowds on lateral structural properties, a pedestrian from a crowd is simulated by a walking bipedal robot. A simplified theory for structural vibration is proposed based on the assumptions of uniform distribution and synchronized walking of pedestrians. This theory can be used to describe the effect of the change in crowd size on lateral structural damping and the frequency of the structure. The method can estimate the variations in structural properties in the case of a certain crowd for engineering design. The results show that the increase in crowd size results in decrease in structural natural frequency in the lateral direction, but increases structural damping. The influence of the crowd on structural properties agrees well with the non-simplified model. Change in walking frequency has little influence on the structural properties. However, the continuous increase in crowd size on structure top causes a non-convergent amplification of dynamic response under a resonant walking excitation. This research provides a quantitative assessment on the effect of crowd size on the change in structural properties for structural design or serviceability evaluation.

A kind of design of 6-DOF transportation vibration platform was introduced. Based on the principle of Space Mechanism, the kinematics model of 6-DOF transportation vibration platform was described and the design of position servo-control system was presented. With a motion simulation experimental, the comparison results of Output/Input data in different directions were obtained. The results show that the vibration data are reproduced very well on the platform within the main frequency range in six directions.

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This study explores the dynamic behavior of beam induced by bipedal pedestrian traffic and corresponding vibration reducing method by tuned mass damper. Each pedestrian from motion crowd simplifies as a bipedal robot comprised of a lump mass and two massless spring-damping legs. In addition, the tuned mass dampers are installed on the bottom of structure to relieving the vibration of structure. The interactions among pedestrians, tuned mass dampers and structure are considered to establish a governing equation. Research indicates that both the tuned mass damper and pedestrian evidently alter the structural properties of the structure by affecting its frequency and damping capacity. The structure tends to be gently flexible at a lower frequency as pedestrian walk across its surface, but the corresponding damping capacity of the structure is improved. The tuned mass damper always improves both the vibration response and dynamic properties of structure. However, its self-dynamic characteristics of the tuned mass damper tend to deteriorate. The tuned mass damper relieves effectively the lateral vibration in a slender structure than the rigid structure. The change in the mass ratio of tuned mass damper to structure affects significantly the dynamic behaviors of structure. In addition, the layouts of the tuned mass dampers on structure also have remarkable influences on the behaviors. The results of this study provide potential pathways for understanding the vibratory mechanisms of slender structures such as footbridges, grandstands, or stations under crowd excitations.