Chapter 21 Evaluation of Mass-Spring-Damper Models for Dynamic Interaction Between Walking Humans and Civil Structures Ahmed S. Mohammed and Aleksandar Pavic Abstract Dynamic interaction between walking humans and vibrating flexible structures is one of the main challenges when simulating human-induced vibrations. To account for this interaction, several mass-spring-damper (MSD) models featuring different parameters have recently been proposed. This paper compares the performance of six experimentally-based MSD models of walking humans available in the literature. The simulated vibration responses of these models were compared with experimental measurements of four human test subjects walking on a full-scale flexible footbridge. Numerical simulations were carried out for two cases: non-interactive and interactive models using the above mentioned MSD models. Moreover, for each case two models of walking forces were used: previously measured continuous walking forces (from a treadmill test) for the corresponding test subjects and a deterministic walking force function from design guidelines. It is demonstrated that neglecting human-structure interaction in the simulations can result in a significant overestimation of the vibration responses. By utilising any of the interactive models of walking people, the accuracy of the vibration response predictions can be improved. The best performance was obtained when both the measured walking forces and the interactive model were used. Keywords Human-structure interaction • Human-induced vibrations • Walking forces • Mass-spring-damper • Footbridge 21.1 Introduction The advancements of structural materials and design techniques have enabled engineers to design more slender and longer span civil structures such as footbridges, floors and grandstands. While the strength requirements are usually assured, the structural design of such structures has been increasingly governed by vibration serviceability criteria related to human dynamic excitation including walking and running [1]. There is a growing number of cases of structures which are either over- or under-designed for vibration serviceability according to current design methods. This indicates a lack of reliable methods for prediction and assessment of humaninduced vibration [2]. For lightweight slender structures, one of the main challenges in developing such methods is the complexity of the dynamic interaction between walking people and their accommodating structure [3, 4]. To consider using this interaction in a design method, recently, there has been proliferation of walking-related human-structure interaction (HSI) models [5]. The performance of these models have not been compared with each other, and therefore, there is a need to evaluate their performance using experimental measurements. This paper compares the performance of six experimentally-developed HSI models for walking humans [6–11]. Experimental measurements pertinent to four people walking on a full-scale slender footbridge were used for this purpose. Furthermore, two models of walking forces were utilised in the analysis: measured walking forces (from nominally identical treadmill walking test for corresponding test subjects) and the traditional walking force model based on Fourier series representation. A.S. Mohammed ( ) •A. Pavic Vibration Engineering Section, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Kay Building, North Park Road, Exeter, EX4 4QF, UK e-mail: asm221@exeter.ac.uk © The Society for Experimental Mechanics, Inc. 2017 J. Caicedo, S. Pakzad (eds.), Dynamics of Civil Structures, Volume 2, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-3-319-54777-0_21 169
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