Download Part 1 of 2: Undertaking Seismic Risk Assessments for Buildings

Part 1 of 2:
Undertaking Seismic Risk
Assessments for Buildings
Occupied by Government agencies
Government Property Management Centre of Expertise
in consultation with
The Ministry of Business, Innovation and Employment
Updated August 2013
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Contents
1. Objective
2. Scope of guidance
3. Risk management framework
4. Sufficient information to make decisions
5. Choosing a course of action
6. Landlord obligations
7. Advice for building owners regarding earthquake safety of buildings
from the Ministry of Business, Innovation and Employment
8. Tolerable risk
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1. Objective
To provide agencies with guidance in utilising information from the Initial Evaluation
Process (IEP) and detailed structural assessments and to assist Government
agencies (agencies) to make informed decisions and develop appropriate responses
to identified risks.
2. Scope of this guidance
The Government Property Management Centre of Expertise (PMCoE) has developed
this document to encourage consistency in approach and outcomes where agencies
have obtained an IEP or detailed structural assessment by a registered structural
engineer.
PMCoE acknowledges that a “one size fits all” approach is not appropriate for all
agencies when developing appropriate responses to buildings with identified seismic
risk. This document highlights key considerations that agencies should take into
consideration during the decision making process.
3. Risk management framework
In considering the response to seismic assessment reports it is useful to recognise
that what is being undertaken is the management of risk. Using a recognised risk
management framework to work through the issues, risks and options will ensure that
a systemic approach is taken when making decisions.
A suggested framework is:
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Define the issues and put them in context;
assess the risks (immediate and longer term) associated with the issues
identified and the benefits;
identify and analyse options for addressing the risks;
select an appropriate response to address the risks identified;
implement response; and
monitor and evaluate results.
It is recommended that the framework is undertaken:
• In collaboration with stakeholders; and
• consideration is given to any new information that may become available that
impacts on the initial risks identified.
It is important to identify the issues and fully understand the potential consequences.
To achieve this, agencies need to ensure that information obtained is correct.
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4. Sufficient information to make informed decisions
Agencies should ensure that they have all the information and understand the
potential issues before decisions are made. Much of the recent publicity around
structural risk has focused on the percentage of new building standard (% NBS).
This however, is only one element within detailed reporting on structural risk.
The calculation of the % NBS is not an exact science and is based on each
engineer’s judgement. Therefore, there may be significant variations in the % NBS
calculation of a building assessment. Furthermore, the % NBS that is provided for in
a detailed assessment reflects the lowest NBS part of a building, for example, if an
engineer concludes that a building has an NBS of 33% or less, it does not
necessarily mean that the entire building is earthquake prone. It could be that only
one specific element of it is (i.e. the outer building surface, the “façade”).
If a landlord is not intending on obtaining a detailed assessment where the IEP
suggests seismic risks could exist, agencies should engage a registered structural
engineer to obtain a detailed assessment. Detailed assessments provide more
specific structural information. Therefore, if an IEP has identified the possibility of
seismic risks, it is advisable to obtain a detailed structural assessment.
If it is identified that a specific part of the building could present a risk (for example,
stairs, floor seating’s and column ties) refer to the publication from the Ministry of
Business, Innovation and Employment called ‘Practice Advisories’.
These
publications highlight areas of a building that require assessment for earthquake risk
and provide guidance. Refer to (http://www.dbh.govt.nz/practice-advisories-index)
for the ‘Practice Advisories’.
It is important for agencies to analyse the seismic assessment reports to fully
understand the structural issues and risks that are the foundation of the % NBS
rating.
Agencies should review the engineer’s reports and be satisfied that they:
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Clearly describe any structural weaknesses within the building.
structural weaknesses should be highlighted.
Critical
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Explain the potential consequences, risks and impacts of the weaknesses
identified on the buildings performance in a moderate earthquake. In
particular what aspects pose a risk to life safety of building occupants and
users.
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Provide clear recommendations on options to address the identified structural
weaknesses with cost estimates.
Agencies should consider other occupants within their buildings, in particular other
Government agencies. Assessments and information should be shared and a coordinated response undertaken. Any associated costs should also be shared
amongst building occupants.
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5. Choosing a course of action
Each building assessed is unique in character, age, construction, location and use.
Agencies need to be cautious about adopting a generic course of action for buildings
in their property portfolio.
Agencies need to exercise judgement based on the information obtained and
evaluate the risks posed from engineers and their assessments.
In choosing a course of action in response to seismic assessments agencies should:
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Prioritise the safety of staff and the public – the appropriate response will
be determined by the identified structural weaknesses and their immediate
potential risk to life safety or of injury. The safety of staff and the public must
be a primary focus in choosing a course of action.
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Address statutory and policy requirements – these would include relevant
policies put in place by a local territorial authority and all health and safety
requirements as set out in relevant legislation. The Ministry of Business
Innovation and Employment has published guidance for building owners
(refer to section 7 for a summary of this guidance).
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Minimise impact on staff and public – business continuity, maintenance of
services and consideration of the personal impact on staff should be factored
into response options developed.
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Consider potential impact of response on other stakeholders – agencies
need to have regard to possible perceptions and precedence that their
response might generate and develop appropriate mitigating strategies where
risks are identified.
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Consider heritage requirements – Cabinet approved a policy in 2004 called
the Policy for Government Departments’ Management of Historic
Heritage.
This Policy provides useful guidance on the management of heritage
properties owned by Government departments. The Government developed
the policy for Government departments only but agencies in the wider state
sector may also find it helpful.
The Policy is available on the Ministry for Culture and Heritage website:
http://www.mch.govt.nz/research-publications/our-research-reports/policygovernment-departments-management-historic-heritage.
Policy 11 may be of particular interest as it directs agencies to the New
Zealand Historic Places Trust (NZHPT). NZHPT is the lead national heritage
agency and it can provide advice to property owners on heritage
management.
If you have general questions about the Policy, contact the Ministry for
Culture and Heritage directly.
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Ensure response is practical and achievable – challenges exist where
issues are identified in leased premises (see Section 6). Practical and
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achievable responses are also linked to the balancing of investment potential cost and risk.
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Ensure response investment corresponds with risk – agencies will be
faced with a range of options from doing nothing, undertaking a full upgrade
or seeking new accommodation. It is important that consideration be given to
the risks that have been identified and a judgement made on where the
balance between unacceptable and tolerable risk lies (see Section 8). This
will help inform decisions about the appropriate level of response and ensure
prudent investment.
6. Landlord obligations
Most agencies will be occupying buildings that are leased from third party landlords.
In relation to seismic assessments and responding to the issues identified, the lessor/
lessee relationship adds a further dimension and can bring with it some challenges.
It is important that agencies understand the boundaries within which they are
operating before they approach their landlord.
Some key points to recognise are:
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The contents of the agencies lease will determine what, if any, the landlord’s
obligations are to provide information, conduct seismic assessments and
undertake remedial work. There is no other legislative authority that directs
landlords in this area other than policies in place by local territorial authorities.
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The Building Act defines earthquake prone buildings as those having a NBS
rating of 33% or less. While some local territorial authorities have goals
contained in their policies for building upgrades (67% NBS is common),
building owners cannot be compelled to undertake more work than is required
to remove the earthquake prone status unless change of use occurs or they
are required, such as through specific lease clauses.
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Owners of buildings assessed at 34% NBS or greater cannot be compelled to
undertake earthquake strengthening work unless a change of use or
significant upgrade occurs.
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Agencies have obligations as an employer under the Health and Safety in
Employment Act 1992 (Health and Safety Act) one such obligation being the
provision of a safe working environment for employees or people in the
vicinity. The focus of the Health and Safety Act is not the meeting of
minimum standards. Rather it sets an expectation that where hazards are
identified, all practical steps are taken to remove or minimise the risk posed.
It needs to be recognised that compliance with the Building Act 2004 and any
policies put in place by a local territorial authorities may not always mean that
the requirements of the Health and Safety Act have been met. Employers
need to exercise judgement in this respect.
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7. Advice for building owners regarding earthquake safety of buildings from
the Ministry of Business, Innovation and Employment
Building owners are responsible for ensuring their building is safe. If a building
owner has concerns about their building, they should seek expert advice and act on
it.
Building owners may be legally required to structurally upgrade their building in the
following situations:
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When the building’s use is going to be changed, it must comply as nearly as
reasonably practicable with the Building Code Structural requirements, as
well as means of escape from fire (typically fire exits and alarms), sanitary
facilities and disabled access.
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If the building is dangerous, insanitary or earthquake prone.
An ‘earthquake-prone building’ is a structure that is 33% or less of the new building
standard (NBS) for earthquake strength design.
Building owners should not wait for the Council to act before dealing with any
structural concerns.
If you have concerns about your building, you should seek expert advice and fix any
identified problems to the extent practicable.
The New Zealand Society of Earthquake Engineering recommends that buildings
should be strengthened to at least 67% NBS, although owners should not rely solely
on the NBS in assessing what action to take.
Being ‘earthquake prone’ doesn’t necessarily mean that your building should not be
occupied but it does mean that you should get an expert engineering assessment as
soon as possible and work out a plan to earthquake strengthen the building.
Building owners who are concerned about their buildings should take the following
steps:
1.
Prioritise building assessments: Make an assessment sooner if the building is
used frequently by large numbers of people and is a higher-risk type (For
example, unreinforced masonry).
2.
Find out everything you need to know to assess risk by obtaining expert
engineering advice on:
The structural strength of the building. Identify any features, critical structural
weaknesses or defects that may be risky
Any strengthening work already done
Possible short term actions that may decrease risk
Other longer term strengthening measures consistent with Council policy and
the building owner’s circumstances and plans.
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Decide what action to take:
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Choose the option that provides the best fix, is practical and cost effective,
meets Council needs and provides least disruption to tenants, users
neighbours and the community
In some instances, it may be necessary to close parts or all of the building
pending repair
Building owners should talk to their tenants about how best to do any
strengthening work needed within a reasonable timeframe.
8. Tolerable risk
The tolerable risk is defined as a risk society or an individual is willing to live with so
as to secure the benefits from taking that risk (for example, the risk of flying versus
the benefits of travel) in the belief that the risk is properly being controlled, reviewed
and further reduced as and when possible.
In everyday life people face a variety of risks and make judgements on whether those
risks are broadly acceptable, tolerable or unacceptable.
In the context of considering seismic assessment of buildings it is important to have a
clear view of what is needed to minimise the risk the structural issues identified raise,
recognising it is impossible to eliminate all risk. The ultimate goal of structural work
is to provide life safety for occupants and users while acknowledging that in a future
seismic event the building could well be damaged beyond repair.
To ensure that no unnecessary cost is incurred, agencies need to form a view of
where the tolerable risk point is in relation to a particular building and balance this
against the requirement to keep staff and the public safe. In addition they should
develop strategies and communication approaches to ensure that those impacted are
fully informed and understand the rational of such decisions.
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