Gordon Campbell | Parliament TV | Parliament Today | News Video | Crime | Employers | Housing | Immigration | Legal | Local Govt. | Maori | Welfare | Unions | Youth | Search

 


Research Launched To Help Homes Better Withstand Earthquakes

Research Launched To Help Homes Better Withstand Earthquakes

A key research project, to help improve the resilience of the types of homes that performed poorly in the Christchurch earthquakes, has been launched.


Engineering experts from BRANZ, with research support from EQC, will use computer modelling to assess the impact of simulated seismic action on modern homes with more complex configurations.


The research has been prompted by findings that less complex homes in Christchurch performed better in the quakes than those built beyond the limits of New Zealand Standard 3604.


Variation in the stiffness of the bracing systems in a house is a common occurrence in such homes, especially hillside houses or older houses, which have been altered to make them more open plan.


The experts will examine how the bracing systems of different stiffness interact during a seismic event.


BRANZ and EQC expect the learnings from the research will be used to develop new guidelines for houses built outside the scope of NZS 3604 in order to mitigate the potential damage in earthquake events.


Project leader Angela Liu, a member of the BRANZ team which inspected residential properties for damage in Christchurch, said that one common phenomenon observed during the Canterbury earthquake sequence was the damage at the junctions where bracing systems changed or where the layout of the building changed.


“We found that many older buildings, pre-NZS 3604 Standard light timber framed houses with small windows and smaller rooms, had performed better than many modern buildings with complex seismic resisting systems,” said Ms Liu.


“The team observed more severe earthquake damage in homes which often had a mixture of different seismic resisting systems, either because of the presence of bigger rooms at one end of the dwelling or larger windows included on one side for a better view.


“According to the current regulations, seismic design of buildings mainly focuses on preserving life and our residential houses performed very well in this regard, as observed in Canterbury earthquake sequence.


“Builders and designers are guided by the prescriptive standard, NZ 3604 Timber Framed Buildings unless architectural and structural designers are employed. Bracing elements as per NZS 3604: 2011 are often sheathed timber walls.”


Ms Liu said that nowadays many people want bigger spacing between bracing lines so they can have bigger rooms or windows and, quite commonly, the spacing of bracing lines becomes too large to comply with NZS 3604.


“The designer will bring in an engineer to design just that part of the house and often the engineer will design a specific bracing system, which is almost definitely not sheathed light timber walls as introduced in NZS 3604.


“Or an owner may want to take out supporting walls in an older house to make larger rooms or an open plan living area and the engineer may, for instance, recommend installing a steel portal to brace that wider space.


“Currently, it appears there is often a mismatch between the mixed stiffness bracing elements resulting in some parts of the house moving more than others in an earthquake. We repeatedly found that cracking had appeared at the points where the stiffer and the more flexible bracing met. We also found that the more flexible bracing associated with the desire to take advantage of the view resulted in significant cladding and window damage to the extent that the dwelling was uninhabitable.”


The team also observed cracking in extensions, at the junctions between pre-1978 suspended timber piles and modern concrete slab floors and noted similar problems with houses which had been built on different levels down hillsides.


“We are aiming to find better ways to improve the performance of these more complex houses,” said Ms Liu.


”We will be looking at what the action is in individual areas and the computer model will allow us to adapt the bracing elements to ensure all the elements of bracing work together.


“That will enable us to provide guidance around areas where engineers need to pay more attention in future designs in order to mitigate problems associated with the potential differences in stiffness between the specifically designed bracing elements and NZ 3604 bracing elements.”


Ends

© Scoop Media

 
 
 
 
 
Parliament Headlines | Politics Headlines | Regional Headlines

Greek Riddles:
Gordon Campbell On The Recent Smackdown Over Greece

There had been a fortnight of fevered buildup. Yet here we are in the aftermath of the February 28 showdown between the new Syriza government in Greece and the European Union “troika” and… no-one seems entirely sure what happened. Did the asteroid miss Earth?

It seems to have. The EU still exists. Syriza is now claiming a victory of sorts. It doesn’t help that the only people who do appear to be sure (the Greeks buckled) are claiming the exact opposite to what the other group (the Greeks won!) are saying. Plus, there are bets either way e.g. Bloomberg News: “Its too early to say who caved in to whom.” More>>

 

PARLIAMENT TODAY:

Iraq: Ex-Hostage Says Government Not Putting NZers, Iraqis First

Harmeet Singh Sooden is travelling to Iraq in the coming weeks to work with Christian Peacemaker Teams (CPT) on a short-term assignment. More>>

ALSO:

Joint Statement: Australia-New Zealand Leaders’ Meeting

Prime Minister Key warmly welcomed Prime Minister Abbott and Mrs Abbott to New Zealand. The visit has enabled wide-ranging and substantive discussion that has underlined the strength, value, diversity and warmth of our trans-Tasman relationship. More>>

ALSO:

Press Conference: Peters To Stand In Northland By-Election

New Zealand First Leader Winston Peters has announced his intention to stand in the Northland by-election, citing his own links to the electorate and ongoing neglect of the region by central government. More>>

ALSO:

Gordon Campbell: On The Wage Hike For MPs (and Paul Robeson)

Hard to tell what is more infuriating. Is it the 5.3% increase on the already bloated salaries of MPs, or their pantomime of outrage at being gifted with such a wonderful back-dated bonanza? More>>

ALSO:

No Designers Or Visual Artists: Flag Panel Members Announced

The Government has appointed 12 New Zealanders as members of the Flag Consideration Panel which will engage with the public about a possible new New Zealand flag, Deputy Prime Minister Bill English says. More>>

ALSO:

Labour MP Stands Down From Portfolio: Comment From Carmel Sepuloni

The first I knew of my mother’s charges was when I was called by a reporter yesterday. I spoke to Andrew and we agreed there is a conflict of interest at the present time which means I will temporarily stand aside from the Social Development portfolio. It’s the right thing to do… . More>>

ALSO:

Gordon Campbell: On Whether NZ Troops Are The Least Of Islamic State’s Problems

Given that it has been politically packaged and sold as a training mission, the Iraq deployment announced yesterday by Prime Minister John Key seemed to be mysteriously short of actual trainers... The other wing of the argument is whether a troop deployment is (a) the only effective way and (b) the appropriate time to combat Islamic State. More>>

ALSO:

Get More From Scoop

 

LATEST HEADLINES

 
 
 
 
 
 
 
 
Politics
Search Scoop  
 
 
Powered by Vodafone
NZ independent news