Vibration Analysis And Performance Evaluation Of Floor System Under Human-induced Excitation

For some structures, which are characterized by light weight and large span, suchas floor and footbridge structures must meet the demand of strength and deformation.However, the vibration serviceability of these structures should also be accounted.Human-induced vibration analysis based on serviceability of floor structures has gotmore and more important.In some European countries, some design guidelines and criterions concernedhave promulgated many years ago such as BSI、AISC series and so on. In recent years,the UK Concrete Society (2005), the UK Concrete Centre (2006) and the UK SteelConstruction Institute (2007) have successively promulgated some new designguidelines, which are all involved in vibration analysis and prediction of structuresunder the force induced by pedestrians. Till today, there are no guidelines of this sortin china. However, the design approach in the guidelines mentioned above have someinsufficiencies, for example, vibration responses are obtained using deterministicharmonic walking force model and only the single dominant mode is taken intoaccount, which may produce inaccurate results. With the ever increasing research onhuman walking gait and the dynamical model of human body in the field ofergonomics and biomechanics, it is possible that the randomness of walking force isconsidered in human-induced vibration analysis of floor structures or footbridges.Moreover, some vibration analysis methods, design guidelines and criterions of floorstructures from other countries have an important referential value for the study of thisaspect in our country.In this paper, the main points include dynamic characteristics analysis of actualfloor system, simulation of force induced by walking persons, multi-modal responseunder walking force and performance evaluation based on serviceability. Dynamiccharacteristics and probabilistic response analysis are conducted combining numericalsimulation with in-situ dynamic measurement. First, FRF-based shaker modal testingis conducted and actual modal parameters of floor structure are identified.Probabilistic multi-harmonic walking force models, both for a single person walkingand for the crowd walking, are established, in which the variability for every walkinghuman is included. Then, for an actual floor structure, which modal characteristics areobtained by a dynamic test under artificial excitation, the multi-mode responses are calculated under probabilistic walking loading. In this process, dynamic behavior ofthis floor under different levels of the acceleration response is investigated speciallyusing free decay analysis. Finally, for a multitude of obtained response specimen,statistical analysis is used to get the response distributions and probability that thevibration level is within a certain range. These results can be used to provide areference for vibration evaluation of a specific project practice.