Citation

Al Abadi H, Lam N, Gad E. J. Earthq. Eng. 2006; 10(6): 775-814.

Affiliation

Department of Civil and Environmental Engineering, University of Melbourne, Parkville, Vic. 3010, Australia

Copyright

(Copyright © 2006, Informa - Taylor and Francis Group)

DOI

unavailable

PMID

unavailable

Abstract

The displacement-based modelling methodology which has been applied extensively to buildings and bridges is extended herein to model the over-turning behaviour of rigid free-standing objects. The acceleration- displacement relationship associated with the overturning motion is linearised in order that the maximum displacement experienced by the object can be estimated using the elastic displacement response spectrum of the building floor. Whilst overturning motion is characterised by highly nonlinear acceleration-displacement properties, it was observed that modelling errors arising from nonlinear behaviour can be effectively controlled through limiting the maximum displacement of the object to some 50% of the ultimate displacement for overturning. The 50% safety margin is one of the key features in the proposed model. Three rigid rectangular objects with depths of 100mm, 300mm and 500mm were used initially to illustrate the use of the model. The height of these objects was 0.5m, 1.5m and 2.5m respectively in order that every object has a common aspect ratio of 1:5. Despite that the aspect ratios of the objects were the same, they have very different levels of vulnerability to overturning. The proposed model was evaluated by nonlinear time-history analyses involving pulse-type excitations, recorded earthquake excitations and computer simulated earthquake excitations. Linear elastic models of buildings have also been used to simulate floor motions at the upper levels in the building. Predictions using the proposed linearised model based on the use of elastic response spectrum of the building floor was found to be very consistent with results obtained from nonlinear time-history analyses. Sufficient verification analyses have been carried out to provide the initial indications that the proposed linearised model seems to work well despite its simplicity.