Seismic actions on acceleration sensitive non-structural components in ductile frames
Earthquake loadings standard NZS 1170.5:2004 has introduced new provisions for the design of building parts and non-structural components. The provisions include factors to define peak floor acceleration up the height of a building, and acceleration response amplifications for components that are quite different from overseas counterparts. In this study, acceleration demands on non-structural components located in ductile frame buildings are analysed under earthquake records from crustal and slab events, for design levels representing ultimate limit state and serviceability limit state.
A floor response spectra approach is used to study the demands on non-structural components. It is noted that the peak floor acceleration demands with respect to that of the ground are not amplified up the height of the building to the extent suggested in NZS provisions. The floor response spectra show peaks near the modal periods of the building indicating higher demands on the components with periods closer to the building period. However, NZS provisions fail to include this effect, since the spectral response amplification is defined independent of building period. Spectral demands exceed the NZS provisions at the fundamental periods of the buildings, more significantly at serviceability conditions, indicating potential failure of non-structural components with periods close to the building periods.
Following the analytical observations from the buildings considered in this study it is clear that the design provisions for non-structural components should be linked to the structural response for specific performance levels rather than the ‘life-safety’ performance level only that is currently adopted in the New Zealand design standard.
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