CUED Publications database

Vibration modes and equivalent models for flexible rocking structures

Acikgoz, S and DeJong, MJ (2017) Vibration modes and equivalent models for flexible rocking structures. Bulletin of Earthquake Engineering, 15. pp. 4427-4452. ISSN 1570-761X

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Predicting the displacement and force response of flexible rocking structures to ground motion is important for their assessment and design. Insofar as practical, it is desirable to use simple mechanical models to make these predictions. However, the complex coupling between rocking and vibration makes accurate predictions with simple models difficult. In this paper, the use of semi-coupled equivalent models to approximate the dynamic response of multi-mass structures rocking on rigid ground is evaluated. These equivalent models feature a two-degree of freedom coupled rocking oscillator to describe the interaction of rocking and the first mode of vibration, and uncoupled linear elastic oscillators to describe higher mode vibration response. To evaluate these equivalent models, the modal components of the dynamic response of multi-mass structures are first determined. These components highlight the critical influence of the excitation of vibration modes at impact. Then, further investigations are carried out by comparing equivalent model simulations to recent shake table tests and multi-mass analytical model simulations. These comparisons reveal that the equivalent models can capture the rocking response accurately for a realistic range of displacements, if a new ground acceleration scaling term is adopted. However, the uncoupled linear elastic oscillators do not consider excitation at impact and consequently, the equivalent models do not capture the acceleration response adequately. Therefore, on the basis of the analytically identified modal components, a further modification that improves the equivalent model acceleration predictions is proposed and validated.

Item Type: Article
Uncontrolled Keywords: modal analysis equivalent model rocking uplift shake table
Divisions: Div D > Structures
Div D > Construction Engineering
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:26
Last Modified: 10 Apr 2021 00:42
DOI: 10.1007/s10518-017-0128-4