Measuring human-induced vibrations of civil engineering structures via vision-based motion tracking

Feng Zheng,Ling Shao,Vitomir Racic,James Brownjohn

doi:10.1016/j.measurement.2016.01.015

Abstract

We present a novel framework for measuring the body motion of multiple individuals in a group or crowd via a vision-based tracking algorithm, thus to enable studies of human-induced vibrations of civil engineering structures, such as floors and grandstands. To overcome the difficulties typically observed in this scenario, such as illumination change and object deformation, an online ensemble learning algorithm, which is adaptive to the non-stationary environment, is adopted. Incorporated with an easily carried and installed hardware, the system can capture the characteristics of displacements or accelerations for multiple individuals in a group of various sizes and in a real-world setting. To demonstrate the efficacy of the proposed system, measured displacements and calculated accelerations are compared to the simultaneous measurements obtained by two widely used motion tracking systems. Extensive experiments illustrate that the proposed system achieves equivalent performance as popular wireless inertial sensors and a marker-based optical system, but without limitations commonly associated with such traditional systems. The comparable experiments can also be used to guide the application of our proposed system.

Highlights

IntroductionThere have been many problems related to vibrations of floors[1], footbridges [2], assembly structures (grandstands, spectator galleries, etc.), due to crowds or groups of human occupants walking, running, dancing and jumping
In civil engineering dynamics, there have been many problems related to vibrations of floors[1], footbridges [2], assembly structures, due to crowds or groups of human occupants walking, running, dancing and jumping
In 2000 during a concert event, the cantilevers of the Cardiff Millennium stadium experienced excessive vibration amplitudes caused by people jumping so that the concert had to be stopped

Summary

Introduction

There have been many problems related to vibrations of floors[1], footbridges [2], assembly structures (grandstands, spectator galleries, etc.), due to crowds or groups of human occupants walking, running, dancing and jumping. The research results were incorporated into two key design guidelines relevant to crowd loading of footbridges (France) [5] and grandstands (UK) [6] for civil engineers. Attempts to measure human induced loading [16,17,18] were based on direct force identification using force plates and instrumented treadmills. Their size places restrictions on studies of loading induced by multiple people [18]. Using the acceleration and mass of the individual, the GRF generated by a crowd can be computed by

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Conclusion