The 4th of September 2010 Mw 7.1 Darfield (Canterbury) earthquake had generated significant ground shaking within the Christchurch Central Business District (CBD). Despite the apparently significant shaking, the observed structural damage for pre-1970s reinforced concrete (RC) buildings was indeed limited and lower than what was expected for such typology of buildings. This paper explores analytically and qualitatively the different aspects of the "apparent‟ good seismic performance of the pre-1970s RC buildings in the Christchurch CBD, following the earthquake reconnaissance survey by the authors. Damage and building parameters survey result, based on a previously established inventory of building stock of these non-ductile RC buildings, is briefly reported. From an inventory of 75 buildings, one building was selected as a numerical case-study to correlate the observed damage with the non-linear analyses. The result shows that the pre-1970s RC frame buildings performed as expected given the intensity of the ground motion shaking during the Canterbury earthquake. Given the brittle nature of this type of structure, it was demonstrated that more significant structural damage and higher probability of collapse could occur when the buildings were subjected to alternative input signals with different frequency content and duration characteristics and still compatible to the seismicity hazard for Christchurch CBD.
An extensive research program is on-going at the University of Canterbury, New Zealand to develop new technologies to permit the construction of multi-storey timber buildings in earthquake prone areas. The system combines engineered timber beams, columns and walls with ductile moment resisting connections using post-tensioned tendons and eventually energy dissipaters. The extensive experimental testing on post-tensioned timber building systems has proved a remarkable lateral response of the proposed solutions. A wide number of post-tensioned timber subassemblies, including beam-column connections, single or coupled walls and column-foundation connections, have been analysed in static or quasi-static tests. This contribution presents the results of the first dynamic tests carried out with a shake-table. Model frame buildings (3-storey and 5-storey) on one-quarter scale were tested on the shake-table to quantify the response of post-tensioned timber frames during real-time earthquake loading. Equivalent viscous damping values were computed for post-tensioned timber frames in order to properly predict their response using numerical models. The dynamic tests were then complemented with quasi-static push and pull tests performed to a 3-storey post-tensioned timber frame. Numerical models were included to compare empirical estimations versus dynamic and quasi-static experimental results. Different techniques to model the dynamic behaviour of post-tensioned timber frames were explored. A sensitivity analysis of alternative damping models and an examination of the influence of designer choices for the post-tensioning force and utilization of column armouring were made. The design procedure for post-tensioned timber frames was summarized and it was applied to two examples. Inter-storey drift, base shear and overturning moments were compared between numerical modelling and predicted/targeted design values.
Questions to Ministers
1. PESETA SAM LOTU-IIGA to the Minister of Finance: What progress has the Government made in building a more competitive economy and getting on top of New Zealand's longstanding reliance on foreign debt?
2. Hon PHIL GOFF to the Prime Minister: Does he have confidence in his Minister of Finance?
3. KEVIN HAGUE to the Prime Minister: Does he stand by all his statements regarding the safety of mining in New Zealand; and does he consider his Government has met all its responsibilities arising out of the Pike River mine disaster?
4. Hon DAVID CUNLIFFE to the Minister of Finance: What are the latest official forecasts for the current account balance and the net international investment position over the next four years under his Government's policies?
5. JONATHAN YOUNG to the Minister of Justice: What progress has been made on the development of alternative court processes for child witnesses?
6. Hon CLAYTON COSGROVE to the Minister of Finance: In light of his statement yesterday regarding foreign-owned assets that "we need to generate the kind of savings that will help New Zealand buy back those assets", is it still the Government's policy to sell State assets if it is re-elected, given that up to 30 percent of the shares he proposes selling could go to overseas buyers?
7. Hon JOHN BOSCAWEN to the Minister of Finance: Does he think that implementing the 2025 Taskforce's recommendations in November 2009 would have avoided New Zealand's double credit downgrade; if not, why not?
8. GRANT ROBERTSON to the Minister of Health: Has he been advised of a reduction in funding for home-based health support services in the Wellington region?
9. TIM MACINDOE to the Minister of Corrections: Has she received any progress reports on the implementation of the Government's Prisoner Skills and Employment Strategy?
10. STUART NASH to the Minister of Finance: By how many percent has the GDP per capita gap between Australia and New Zealand widened since his Government took office?
11. NIKKI KAYE to the Minister for Communications and Information Technology: How many schools will benefit from ultra-fast broadband in the first year of the roll-out?
12. BRENDON BURNS to the Minister for Canterbury Earthquake Recovery: Does he stand by all of his statements on Canterbury's earthquake recovery?
Questions to Members
1. SU'A WILLIAM SIO to the Chairperson of the Social Services Committee: Will she call a meeting to consider the Inquiry into the identification, rehabilitation, and care and protection of child offenders; if not, why not?
