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Displacement controlled behaviour of strength degraded structures

This research study represents an important contribution towards fulfilling the long-term objective of the research program in terms of assessing and controlling seismic risks of building structures in low and moderate seismic regions such as Australia. The research outcome enables the existing building stock to be assessed in an inexpensive way. Post-disaster agencies and insurance agencies could then better assess risk exposure. The displacement controlled phenomenon associated with conditions in low and moderate seismic regions has become the basis of a new performance assessment methodology for strength degraded structures. / In low and moderate seismic regions the kinetic energy demand generated by a small or medium magnitude earthquake (M<7) (at an epicentral distance consistence with Peak Ground Velocity (PGV) of up to 80 mm/s on rock) will generally subside when the structure has been displaced to the maximum limit. Current design guidelines in seismic design and assessment of structures has been based on trading-off strength with ductility demand to accommodate large displacement without significant strength degradation to ensure that structures have sufficient energy dissipation capacity. The drift capacity recommended for strength degraded structures is quite low as per the current guidelines which are developed for high seismic regions and it is considered that a structure is deemed unsafe when the lateral strength has degraded by more than 20%. An important investigation has been undertaken to determine if such structures are actually unsafe, should the displacement controlled phenomenon be taken into account. / Therefore, the research described in this thesis is aimed at capitalizing the displacement controlled concept (not to be confused with the displacement based design methods) which is particularly relevant for low and moderate seismic regions for investigating the seismic performance of strength degraded structures. If the peak displacement demand (PDD) and the displacement capacity of the structure are known then the displacement based approach can be applied directly for assessing the performance of the structure. The seismic displacement demand is then simply compared with the displacement capacity to ensure that its gravity load carrying capacity is not compromised in the projected earthquake scenario. / A full scale testing was carried out under quasi-static conditions on a soft-storey building which was representative of existing building stock in low-moderate seismic regions to investigate the force-deformation relationship and drift capacity of soft-storey buildings. Data obtained from the full-scale experimental field studies on the force displacement behaviour of the building has been used as input into the nonlinear time history analyses to study the seismic response behavioral trends of soft-storey buildings. / A new simple methodology for estimating the peak displacement demand of inelastic nonlinear systems, which is based on the elastic displacement response spectra, was introduced. The major findings from the parametric studies shows that highest point on the elastic displacement response spectra can provide a conservative prediction of the maximum displacement demand of non-linear inelastic systems.

Identiferoai:union.ndltd.org:ADTP/280804
Date January 2010
CreatorsBhamare, Rupali S
Source SetsAustraliasian Digital Theses Program
LanguageEnglish
Detected LanguageEnglish
RightsRestricted Access: Abstract and Citation Only Available

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