Earthquake Issues for Commercial Buildings

[eri]

^

i don't think so

but it probably should

if these world wide quakes

start to settle down over the next 20?

that may be the next step

[John the builder]

The standards have a Zfactor that Nick Smith has used to evaluate low risk areas

z factor is measure of Peak Ground Acceleration which I understand to mean the leval of shaking. Movement from EQ occurs at faultlines and as you are distant from them the PGA reduces. Auckland doesnt have proximity to faults hence affects of central Nth Island faults is limited

The Z factor for Auckland and northland and dunedin is set at .13 but this is artificilial high and reflects the minimum EQ strength desired in a new build. GNS who set the factors increased Chch after the EQ's to .3 but at the same time recognised Auckland could be lowered to .08 which puts it in the never going to happen category. (They should be building for tsunamis and volcanoes in Auckland)

The Standards allow for local areas to have special studies to understand the risk and then remove EQ consideration all together. A friend of mine has been advocating to allow this assessment to be done on a regional basis to save cost for individual owners but hitting a brick wall.

The bureaucrats dont know how to deal with this issue and imposing a standard on the whole country is their solution

[Wayne]

So even though it is recognised that the risk is different in different areas all areas have to build to the same standard?

[John the builder]

the z factor recognizes that is one area the forces that are expected will be lower than in an area with a higher z factor.

When an assessment is done for NBS the local Z factor will be used

They are built to the same standard but this standard allows for different loads from EQ. The same applies to Wind loads a building is a high wind zone has to be stronger than one in a low wind zone. (with EQ loads building in high z factor area are stronger than low z factor area)

A 34% NBS building in wellington will be stronger that a 34% NBS in Auckland but this reflects that it needs to be to withstand likely EQ loads.

If the true GNS Z factor (0.08 instead of .13 minimum) could be used in Auckland then the 34% NBS could be a 44% NBS or a 24%NBS (considered EQ prone) could in fact be 34% and not actually EQ prone at all?

If a study allowed for EQ to be ignored the affect could be to lift all buildings (or at least 90% of them as some may already be falling down without the need for a shake) immediately to perhaps100%NBS. (because the standard no longer required EQ to be considered and the building now complied with 100% of the standard

[Wayne]

All sounds reasonable to me.
Though buildings need to be upgraded to 34% or 70% or any other % the 100% is relative to the risk
so is fair to all areas.
In low risk areas little work would need to be done you's expect.

[John the builder]

but in fact the low risk areas are given an artificially high factor and this does create a lot of work and cost

[eri]

thanks John

good explanations

[Wayne]

so the issue is the risk assesment not the % to aim for.
Fair enough - I understand now.

[John the builder]

the issue should be will the building fall down in a moderate EQ and injure and kill. If it would then it is EQ prone

Govt sets the moderate EQ as at 33% of what might be expected and this has been taken to mean 33% of NBS (new build standards)

The first part of that is; what is the liklehood of a mod EQ in a reasonable period of time and regs say 500 year return period.

If you strengthen a building to greater than 34% it will be less likely to collapse in a more than moderate EQ but it will still anyway likely need demolishing after the event as uneconomic to repair.

That is the sillyness in this issue when banks and the like ask for greater than 34% as the bldg will need replacement anyway. This is what happened in Chch and why there was a razed earth response it was driven by insurers settling for replacement so they could avoid cost of repair issues.

[eri]

1 of the smart + positive spin-offs of this decision

is builders and construction companies will now be available

for addressing ak's housing shortage

otherwise lefty policy wonks

would have set the scene

for large commercial farms

to pointlessly strengthen hay sheds

[Davo36]

The council doing it's best to put people out of business once again:

Franz Josef on edge following Alpine Fault ruling

Franz Josef residents are asking themselves "what next?"

Independent commissioners this week accepted a plan for a fault avoidance zone through the town. Franz Josef straddles the Alpine Fault and would be seriously at risk in a major earthquake.


Though businesses located within the 200-metre wide zone could stay put, there would be tight regulations on future developments.

Link

[artemis]

Good article in the NBR by Chris Gudgeon, CEO of Kiwi Property - Equitable tax treatment of earthquake strengthening costs needed

Brief extract -

"... property owners unable to strengthen their buildings will have no choice but to relinquish them, creating the prospect of cities and provincial towns peppered with unsafe, derelict and abandoned buildings. This scenario, as a consequence, will undermine local authorities’ rating bases, and the burden of dealing with earthquake-prone or structurally obsolete buildings will increasingly fall on central and local government as the private sector is discouraged from meeting these costs. The government has made a positive start by introducing a more targeted approach for earthquake-prone buildings, as recently announced by Building and Housing minister Nick Smith. However, this must be followed by a review of the tax laws covering earthquake strengthening."

http://www.nbr.co.nz/article/equitable-tax-treatment-earthquake-strengthening-costs-needed-176493

[speights boy]

Government halves timeframe to fix most dangerous buildings

The Government has halved the timeframe to make the country's most earthquake-prone buildings safer after pressure from a Christchurch earthquake survivor.

Building and Housing Minister Nick Smith said the changes were direct result of advocacy from Ann Brower – the sole survivor of a bus crashed by falling masonry in the February 2011 earthquake – and would be known as the "Brower Amendment".

He said the changes to the Earthquake-Prone Buildings Amendment Act would focus on the 2000 most dangerous buildings across the country, which had unsecured or unreinforced masonry, requiring them to be assessed within 2.5 years and fixed within 7.5 years.

http://www.stuff.co.nz/national/71679073/government-halves-timeframe-to-fix-most-dangerous-buildings

[John the builder]

i wonder If Nick smith even read Ann Bowers submission?

http://www.parliament.nz/en-nz/pb/sc/documents/evidence/51SCLGE_EVI_00DBHOH_BILL12960_1_A438211/ann-brower-supp-1

Bower didnt say the buildings should be strengthened as a priority she said the bits that fall off should be........

again a group of buildings is being condemned when the focus should be on risk, and the bits that fall on people.

This is the second change That smith has made while the select committee are still considering the issue. What happened to democracy?

[Davo36]

Well we're supposed to believe that the government is jumping there and saving us all. When in fact they've done nothing at all really.