Abstract

Predicting the effect of walking traffic on structural vibrations is a great challenge to designers of pedestrian structures, such as footbridges and floors. This is mainly due to the lack of adequate design guidelines, which in turn can be blamed on poor research findings. Even the fundamental data are very rare and limited. This study proposes a new and more reliable method for serviceability assessment of the vertical vibrations induced by multi-pedestrian walking traffic. Key novelties include modelling the natural variability of the walking forces and the human bodies, as well as their individual interaction with the supporting structure at their moving location. Moreover, a novel approach to vibration serviceability assessment (VSA) is proposed based on the actual level of vibration experienced by each pedestrian, rather than the typical maximum vibration response at a fixed point. Application of this method on two full-scale footbridge structures have shown that, with a suitable calibration of human model parameters, the proposed method can predict the occupied structure modal frequency with less than 0.1% error and - more importantly - modal damping ratio with less than 1% error. The new method also estimated the structural responses with considerably less error (5–10%) compared to a selection of current design guidelines (200–500%). The proposed VSA method is not suitable for hand-based calculations. However, if coded and materialised as a user-friendly software, it can be incorporated into design guidelines and used by consultants in everyday engineering practice.

Highlights

  • Models of pedestrian dynamic loading used in contemporary vibration serviceability assessment typically describe the vertical walking excitation as a vertical force that does not depend on structural vibrations [1]

  • The performance of the interaction-based vibration serviceability assessment (VSA) method was further compared with a number of the relevant design guidelines: ISO 10137 standard [3], French road authorities standard [4], UK National Annex to Eurocode 1 [5] and a method proposed by Butz [35]

  • The interaction-based VSA method proposed in this paper addresses the most important shortcoming of the current vibration serviceability assessment guidelines for pedestrian structures: neglecting the human-structure interaction (HSI) and inter- and intra-subject variability of the walking load and human body parameters

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Summary

Introduction

Models of pedestrian dynamic loading used in contemporary vibration serviceability assessment typically describe the vertical walking excitation as a vertical force that does not depend on structural vibrations [1]. A significant move towards a more realistic estimation of the vibration response was made only recently, by taking into account inter- and intra- subject variability of the pedestrians in statistical models of their walking force [6,7,8,9,10,11,12]. This has increased considerably the fidelity of the walking force models.

Description of assessment method
Input parameters
Step 1
Step 2
Step 3
Step 4
Sensitivity analysis
Experimental verification
Vibration monitoring
Vibration serviceability assessment
Comparison with design guidelines
Findings
Conclusions
Full Text
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