This study was initiated to quantify the effect of different degrees of irregularity on
structures designed for earthquake using simplified analysis. The types of irregularity
considered were:
(a) Vertical Irregularity
• Mass
• Stiffness -Strength
(b) Horizontal (Plan) Irregularity
• Diaphragm Flexibility
Simple models were used to allow many analyses to be conducted in a relatively short
time. For vertical irregularity studies, simple shear-type structures were designed
according to the New Zealand design Standard, NZS1170.5, firstly as regular
structures, and then they were redesigned as irregular structures to the same target
drift. Both regular and irregular structures were then subjected to a suite of records,
and vertical irregularity effects evaluated from the difference in response. For the
flexible diaphragm effect study, simple models of structures were developed with: (a)
a rigid diaphragm assumption; and (b) a flexible diaphragm assumption. Flexible
diaphragm effects were evaluated by conducting time-history analyses and comparing
the responses of structures with rigid and flexible diaphragms. A mechanics based
approach was developed to quantify flexible diaphragm effects, which was shown to
produce consistent results with those from time-history analyses.
Relationships between the degree of irregularity and the change in behaviour were
developed. This information facilitates designers and plan checkers to rapidly
evaluate the likely effect of irregularity on structures. It provides guidance as to: (a)
when the effect of structural irregularity can be ignored, and (b) the change in
demands for different degrees of structural irregularity. The relations developed also
provide a rigorous technical basis for future regularity provisions in the NZS1170.5
and other world-wide seismic design codes.
| Identifer | oai:union.ndltd.org:canterbury.ac.nz/oai:ir.canterbury.ac.nz:10092/5309 |
| Date | January 2010 |
| Creators | Sadashiva, Vinod Kota |
| Publisher | University of Canterbury. Civil and Natural Resources Engineering |
| Source Sets | University of Canterbury |
| Language | English |
| Detected Language | English |
| Type | Electronic thesis or dissertation, Text |
| Rights | Copyright Vinod Kota Sadashiva, http://library.canterbury.ac.nz/thesis/etheses_copyright.shtml |
| Relation | NZCU |
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