Sunday, March 22, 2015
Mike Butler: Opera House safer than drivingLabels: Cynthia Bowers, Earthquake, EQ Struc, Hastings District Council, Holmes Consulting, Lawrence Yule, Mike Butler
The drama involves two buildings, the Hawke’s Bay Opera House and the Municipal Building which was the council assembly room and offices, both built in 1916. Both buildings withstood the devastating 7.8 (Richter scale) February 3, 1931, Hawke’s Bay earthquake that killed 256 people. Both buildings have been strengthened.
A $13.6-million upgrade transformed the Hastings Municipal Theatre into the Hawke’s Bay Opera House in a bid to attract class acts from around the world. The born-again buildings lose at least $200,000 a year and are propped up by ratepayers.
Earthquakes in Christchurch four years ago brought another transformation.
A 6.3 (Richter scale) earthquake struck Christchurch on February 22, 2011, killing 185 people, with 115 deaths occurring in the six-storey Canterbury Television Building, which collapsed and caught fire.
Central government redefined earthquake proneness and set in motion a national requirement to have steel plates bolted on to sections of buildings to have them declared, not safe, but at a certain percentage of new building standard.
Note, the CTV Building that collapsed was built in 1986 by engineers who had considerable understanding of how buildings behave in earthquakes. Most un-reinforced masonry buildings survived the 2011 earthquake.
The story of how the Hawke's Bay Opera House suddenly switched from being the jewel in the Hastings District Council’s crown to a dangerous no-go zone surrounded by safety barriers is detailed in Quake hysteria hits Opera House.
A report done by Holmes Consulting that was released last month includes the results of computer modelling of how the Hawke’s Bay Opera House and the Municipal Building would behave in a 100-year earthquake, costs of three strengthening options to 35 percent of new building standard, to 70 percent, and to 100 percent, illustrations of strengthening, and some nice colour photos of the buildings.
Holmes Consulting used computer modeling to “test” the Opera House and Municipal Building and used data from 100-year return earthquakes including the 2007 Gisborne earthquake, a California earthquake in 1940, and another in Hokkaido, Japan in 2003.
If 1931 Hawke’s Bay earthquake data were used, wouldn’t it be interesting to see whether the computer model results matched those of the actual earthquake. That would immediately show if the computer model was accurate.
The Hastings District Council set its sights on strengthening the buildings to 100 percent of new building standard, an option that would cost $21.7-million.
The announcement came from Hastings mayor Lawrence Yule, a trained engineer, staunchly supported by deputy mayor Cynthia Bowers, who believes the buildings to have iconic status and must be preserved at any cost.
The alleged earthquake proneness of the two fenced-off buildings is a health and safety issue yet, in a cart-before-the-horse approach, the Hastings District Council is rushing ahead to get costs for the $21.7-million strengthening option before identifying safety levels.
A clue to the sort of safety level the new building standard would achieve is included in the Holmes Consulting report that is posted on the Hastings District Council website.
That report cites building standard AS/NZS1170:2002 without any indication that it was loosely linked by those who created the Building Act 2004, to ISO 3000, an international standard of one death in one million years, a safety level that is near enough to being risk-free.
In everyday terms, a standard with a safety level of one death in one million years is 2000 times safer than traveling in a car.
Therefore, the Hastings District Council is considering spending $21.7-million to achieve a safety level that is 2000 times greater than the level of risk we are accustomed to take every day while driving.
Any building owner faced with such an onerous compliance requirement would be keen to settle for a much lower level of safety for a lower compliance cost. But a district council with unlimited access to ratepayer money can behave as if money is no object.
So, how safe are the Hawke’s Bay Opera House and Municipal Building at present?
In March last year, Strata Group and EQ Struc declared the Opera House and Municipal Building earthquake prone, with ratings of between 11 percent and 20 percent of new building standard.
Therefore, assuming the new building standard is 2000 times safer than driving, it is quite likely the buildings in their current state are 220 to 400 times safer than driving your car.
I’m sure that if that level of risk were posted on the doors of the buildings in their current condition, most people would decide quite freely to continue to use the buildings.
The risk of having a big earthquake in Hawke’s Bay has not changed. Buildings have come and gone, with many of those that survived the 1931 quake strengthened – including both the Hawke’s Bay Opera House and Municipal building as already mentioned.
What has changed is Government-driven earthquake paranoia after the 2011 Christchurch earthquakes, something older Hawke’s Bay residents would have watched with amusement, especially those who lived through the 1931 Hawke’s Bay earthquake.
As a result of this knee-jerk reaction, the Ministry of Business Innovation and Employment has claimed that up to 25,000 reasonably sound New Zealand buildings, many of which have been strengthened, are earthquake prone.
This created an opportunity for earthquake engineers to write a lot of business by way of reports on the alleged earthquake-proneness of buildings and by creating designs to bolt steel plates on masonry structures and declare them at a certain percent of new building standard.
A proposal to spend $21.7-million to make the Hawke’s Bay Opera House and Hastings Municipal Building 2000 times safer than driving a car is absurd. Thankfully, ratepayers will be consulted later this year.
Hopefully, as time creates a bit more distance from the Christchurch earthquakes, perhaps a little common sense may be allowed to enter the debate about earthquakes and building safety.
at 1:11 PM