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UBC Theses and Dissertations

A simplified methodology for seismic design and assessment of nonstructural elements Kumar, Awanish

Abstract

Seismic safety of the nonstructural elements has drawn considerable attention of design and research community over past three decades. It is widely recognized that damage to these elements account for a significant portion of total economic loss after an earthquake. Different building codes put guidelines for assessment of these elements, however, need of a simplified and rational method for their seismic design is still felt by practicing engineers. The existing analysis procedures of floor response spectrum method and modal synthesis method are very detailed and cumbersome to be efficiently used in a design office. Expressions recommended by building codes predict a response which, in many cases, is significantly different from observed behaviour of the components. This thesis proposes a simplified and time-efficient methodology for seismic assessment of these elements which will enable engineers to take rational and consistent design decisions. This methodology is based on the concept of floor response spectrum where the acceleration demand corresponding to a component can be read from obtained floor spectrum. The procedure makes use of a simplified continuous model proposed by an earlier researcher to denote structures. An important feature of this methodology is the way of inputting seismic excitation to structures. The seismic excitation is input in form of ‘Design Ground Response Spectrum’ provided in building codes rather than commonly expected way of using groundmotion time-histories. Some results for floor acceleration demands for two sites in Canada are also presented. The methodology is extended to include base-isolated structures also. An independent procedure is proposed for assessment of components placed in the irregular structures. It is based on scaling of the ‘Reference Floor Response Spectrum’. The methodology presented in this thesis can be developed into an ‘Analyzer’ package to be used by practicing engineers for components’ design and assessment for all places in Canada. A useful guiding line for nonstructural element’s assessment to engineer is to decide whether to retrofit, relocate or replace it. This methodology based on the floor spectrum concept should enable designer in taking this decision rationally.

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Attribution-NonCommercial-NoDerivs 2.5 Canada

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