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A coupled biomechanical/discrete element crowd model of crowd-bridge dynamic interaction & application to the Clifton Suspension Bridge

A coupled biomechanical/discrete element crowd model of crowd-bridge dynamic interaction & application to the Clifton Suspension Bridge
A coupled biomechanical/discrete element crowd model of crowd-bridge dynamic interaction & application to the Clifton Suspension Bridge
Much of the guidance available to engineers regarding human-induced bridge vibration and the lateral instability phenomenon that can occur has resulted from experience of ‘one-off’ bridge loading events such as the London Millennium and Paris Solférino bridges. This has resulted in restrictive design criteria for pedestrian numbers and acceleration limits. However, this area has been the subject of extensive research over more than a decade. As a consequence, improved understanding of the problem has enabled the development of better modelling and simulation tools. In this paper, human-induced vibration is considered from two viewpoints, (i) the interaction that takes place between individual walking pedestrians and the vibrating bridge, and (ii) the wider crowd behaviour that results from the interactions between pedestrians. The current state of the art is identified in each area and a modelling framework is presented that couples both. A discrete element crowd model is coupled with a dynamical system. The dynamical system models interaction between multiple inverted pendulum (IP) biomechanical models and a SDoF system representing a bridge vibration mode. Both the crowd model and dynamical system are coupled in a time-stepping framework with crowd model output used to update the dynamical system at each time-step. The model is then used to simulate the multi-modal response of the Clifton Suspension Bridge (CSB), previously documented in the literature. Model predictions show good agreement with observations from the CSB. Most notably, lateral instability develops in a mode at 0.52 Hz followed by instability in a second at 0.75 Hz, without step frequency tuning among the crowd, in line with observations. Furthermore, the model suggests that instability in mode L2 may have lead directly to development of instability in mode L3. The existence of a feedback mechanism has been confirmed and is identified as resulting from amplitude modulation of the lateral ground reaction force. This mechanism results from alteration of the lateral position of the foot in successive steps in response to base oscillations.
Footbridge, human-induced vibration, biomechanical modelling, discrete crowd modelling, lateral dynamic instability, amplitude modulation, bridge vibration
0141-0296
58-75
Carroll, S.P.
883bcf33-c37e-4d4d-b77f-468c77b5e7ee
Owen, J.S.
63c08cad-d6cd-45ce-8313-d1d27a448f8c
Hussein, M.F.M.
3535c131-1710-4edc-a4a1-8fe67dee3f67
Carroll, S.P.
883bcf33-c37e-4d4d-b77f-468c77b5e7ee
Owen, J.S.
63c08cad-d6cd-45ce-8313-d1d27a448f8c
Hussein, M.F.M.
3535c131-1710-4edc-a4a1-8fe67dee3f67

Carroll, S.P., Owen, J.S. and Hussein, M.F.M. (2013) A coupled biomechanical/discrete element crowd model of crowd-bridge dynamic interaction & application to the Clifton Suspension Bridge. Engineering Structures, 49, 58-75. (doi:10.1016/j.engstruct.2012.10.020).

Record type: Article

Abstract

Much of the guidance available to engineers regarding human-induced bridge vibration and the lateral instability phenomenon that can occur has resulted from experience of ‘one-off’ bridge loading events such as the London Millennium and Paris Solférino bridges. This has resulted in restrictive design criteria for pedestrian numbers and acceleration limits. However, this area has been the subject of extensive research over more than a decade. As a consequence, improved understanding of the problem has enabled the development of better modelling and simulation tools. In this paper, human-induced vibration is considered from two viewpoints, (i) the interaction that takes place between individual walking pedestrians and the vibrating bridge, and (ii) the wider crowd behaviour that results from the interactions between pedestrians. The current state of the art is identified in each area and a modelling framework is presented that couples both. A discrete element crowd model is coupled with a dynamical system. The dynamical system models interaction between multiple inverted pendulum (IP) biomechanical models and a SDoF system representing a bridge vibration mode. Both the crowd model and dynamical system are coupled in a time-stepping framework with crowd model output used to update the dynamical system at each time-step. The model is then used to simulate the multi-modal response of the Clifton Suspension Bridge (CSB), previously documented in the literature. Model predictions show good agreement with observations from the CSB. Most notably, lateral instability develops in a mode at 0.52 Hz followed by instability in a second at 0.75 Hz, without step frequency tuning among the crowd, in line with observations. Furthermore, the model suggests that instability in mode L2 may have lead directly to development of instability in mode L3. The existence of a feedback mechanism has been confirmed and is identified as resulting from amplitude modulation of the lateral ground reaction force. This mechanism results from alteration of the lateral position of the foot in successive steps in response to base oscillations.

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More information

e-pub ahead of print date: 25 December 2012
Published date: April 2013
Keywords: Footbridge, human-induced vibration, biomechanical modelling, discrete crowd modelling, lateral dynamic instability, amplitude modulation, bridge vibration
Organisations: Dynamics Group

Identifiers

Local EPrints ID: 354626
URI: https://eprints.soton.ac.uk/id/eprint/354626
ISSN: 0141-0296
PURE UUID: 23a34344-7a15-4ccc-9a3b-31b1dc77431a

Catalogue record

Date deposited: 16 Jul 2013 15:35
Last modified: 16 Jul 2019 21:28

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Contributors

Author: S.P. Carroll
Author: J.S. Owen
Author: M.F.M. Hussein

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