SEISMIC PERFORMANCE OF REINFORCED CONCRETE BUILDINGS IN THE 22 FEBRUARY CHRISTCHURCH

[TAFATNEB]

SEISMIC PERFORMANCE OF REINFORCED CONCRETE BUILDINGS IN THE 22 FEBRUARY CHRISTCHURCH (LYTTELTON) EARTHQUAKE

Author: Weng Y. Kam , Stefano Pampanin , Ken Elwood3 | Size: 5.9 MB | Format: PDF | Quality: Unspecified | pages: 40

Six months after the 4 September 2010 Mw 7.1 Darfield (Canterbury) earthquake, a Mw 6.2 Christchurch
(Lyttelton) aftershock struck Christchurch on the 22 February 2011. This earthquake was centred approximately 10km south-east of the Christchurch CBD at a shallow depth of 5km, resulting in intense seismic shaking within the Christchurch central business district (CBD). Unlike the 4 Sept earthquake
when limited-to-moderate damage was observed in engineered reinforced concrete (RC) buildings [35], in the 22 February event a high number of RC Buildings in the Christchurch CBD (16.2 % out of 833) were severely damaged. There were 182 fatalities, 135 of which were the unfortunate consequences of
the complete collapse of two mid-rise RC buildings.
This paper describes immediate observations of damage to RC buildings in the 22 February 2011 Christchurch earthquake. Some preliminary lessons are highlighted and discussed in light of the observed performance of the RC building stock. Damage statistics and typical damage patterns are
presented for various configurations and lateral resisting systems. Data was collated predominantly from
first-hand post-earthquake reconnaissance observations by the authors, complemented with detailed assessment of the structural drawings of critical buildings and the observed behaviour. Overall, the 22 February 2011 Mw 6.2 Christchurch earthquake was a particularly severe test for both
modern seismically-designed and existing non-ductile RC buildings. The sequence of earthquakes since
the 4 Sept 2010, particularly the 22 Feb event has confirmed old lessons and brought to life new critical
ones, highlighting some urgent action required to remedy structural deficiencies in both existing and
“modern” buildings. Given the major social and economic impact of the earthquakes to a country with
strong seismic engineering tradition, no doubt some aspects of the seismic design will be improved based
on the lessons from Christchurch. The bar needs to and can be raised, starting with a strong endorsement
of new damage-resisting, whilst cost-efficient, technologies as well as the strict enforcement, including
financial incentives, of active policies for the seismic retrofit of existing buildings at a national scale.

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