Seismic Guidelines

Please note that compliance with University Guidelines is expected in normal circumstances, and any deviation from Guidelines – which should only be in exceptional circumstances – needs to be justifiable.

Purpose

To support Seismic Policy by providing operational and application guidance.

To ensure that the seismic performance of the University's property portfolio is managed to an acceptable risk and to ensure improvements are made at optimal cost.

These Seismic Guidelines will be used as guidance to enact the Seismic Policy and be applied by Property Services, Campus Development and its external consultants and contractors.

Organisational scope

These guidelines apply to all University-owned and leased properties covered by the Seismic Policy as managed by Property Services.

Definitions

Critical post-earthquake function

A function which will be required following an earthquake, and which cannot readily be delayed or relocated.

Critical Structural Weakness (CSW)

Any weakness in the building structure that could potentially influence its performance at any level of earthquake shaking.

Detailed Seismic Assessment (DSA)

In depth analysis of a structure's expected performance in a code level earthquake as defined by the EPB Methodology.

Earthquake Prone Building (EPB)

Any building that is determined to be earthquake prone by the relevant Territorial Authority through the application of the Earthquake Prone Building (EPB) Methodology as prescribed through the Building Act 2004 and the Guidelines for the Seismic Assessment of Existing Buildings specifically addressed in sections 133AB , 133AK and 33AB(1) in the Act.

EPB Methodology

The 2017 Guidelines for the Seismic Assessment of Existing Buildings commonly known as “the Red Book” and imposed by the Building Act 2004 and associated amendments.

Heritage Building(s)

A building of significant historic character, appearance and materials which is listed in Schedule 25.1 of the Dunedin City District Plan and/or registered by the New Zealand Historic Places Trust.

Initial Seismic Assessment (ISA)

High level analysis of a structure's expected performance in a code level earthquake as defined by the EPB Methodology.

Life Safety Hazard

A building element with a rating less than 34 per cent NBS where a building failure would lead to the collapse of the building in

New Building Standard (NBS)

The design standard required for new buildings by the New Zealand Building Code.

New Zealand Building Code (NZBC)

The Regulation underpinning the Building Act 2004. All building work in New Zealand must comply with the Building Code, even if it doesn't require a building consent. This ensures buildings are safe, healthy, and durable for everyone who may use them. The Code's earthquake design loadings are set by the New Zealand Loadings Standard NZS 1170.5 (Standards New Zealand, 2004).

Seismic Assessment

An assessment of the structural integrity of a building under earthquake shaking in accordance with the University seismic guidelines.

Seismic Programme Steering Group

The Committee consisting of Property Services, Campus Development and Academic staff responsible to help prioritise seismic strengthening projects and assessments in accordance with these Seismic Guidelines and in accordance with the Seismic Policy.

Serviceability Limit State (SLS)

Building performance where beyond which damage is expected to non-structural elements.

Severe Structural Weakness (SSW)

A defined structural weakness that is potentially associated with a catastrophic collapse and for which the capacity may not be reliably assessed based on current knowledge.

Territorial Authority

Territorial Authorities are local councils that play a key role in the system for managing earthquake prone buildings within there jurisdiction.

Ultimate Limit State (ULS)

Building performance associated with structural failure.

University Seismic Guidelines

Guidance document on building assessment and design of strengthening, alterations, and new builds. To be maintained by the University's Seismic Committee.

Yellow Book

The revised C5 section of the EPB Methodology that provides recommended revisions in undertaking seismic assessments to concrete buildings. This section has not been formally adopted into the EPB Methodology.

Content

These guidelines support the Seismic Policy to enable risk-based decisions to be made in respect of the built environment. This document is intended for use by the University of Otago (University), Property Services Division (PSD), and Campus Development Division (CDD) staff and consultants

The guidelines cover:

• Procuring new buildings for acquisition
• Seeking a seismic assessment of an existing building as instructed by the relevant Territorial Authority under the EPB Methodology
• Undertaking due diligence of a building for business case purposes i.e., plans to undertake a capital project, improvement, demolition, or upgrade
• Seeking a seismic assessment to occupy a building
• Target strengthening requirements of existing buildings, or parts of buildings, where required

1. General

   The University owns, occupies, and operates a large property portfolio in New Zealand and accordingly has a risk based, strategic asset management approach to its portfolio. As the University is a long-term owner-occupier for a significant portion of its property portfolio, the University adopts a holistic approach to achieving the appropriate balance regarding the level of design specification, maintenance requirements, refurbishment and upgrading within the overarching framework of the New Zealand Building Code (NZBC). This applies to resilience, costs, and speed of repair in response to a seismic event.

   These guidelines advise:

   • The level of seismic resilience to be achieved in new builds
   • How to quantify and ensure sufficient seismic resilience in any property acquisition (owned or leased)
   • How to quantify and increase the seismic resilience of existing properties

2. New buildings

   Early decisions in the design of new buildings can greatly improve or detract from the building's seismic performance Well-conceived, well-designed and well-constructed buildings will perform better than other code compliant buildings.

   The University requires the design of all new buildings to consider whole of building seismic performance. This includes structural, non-structural, and seismic restraint considerations. The whole design team must agree and adopt a 'whole of building' seismic performance approach and agree on appropriate design parameters. The project specific approach adopted is to be agreed with the Seismic Assessment Steering Group. Once agreed, these design parameters become performance requirements in addition to those of the NZBC.

   1. Site Specific Seismic Hazard Assessment
      The University requires design teams to consult with the NZBC and/or NZ Standards and to consider undertaking a Site-Specific Seismic Hazard Assessment for all major projects. This is to ensure the design incorporates the latest seismic hazard information, and an appropriate amount of future proofing. The New Zealand National Seismic Hazard Model (NSHM) is subject to major updates, so specific seismic hazard assessments will need to capture and apply the key components of the latest NSHM at the time the Site-Specific Seismic Hazard Assessment is completed.
   2. Importance level
      The minimum requirements for Importance Level (IL) of the Building Act are to be met. The importance level is to be agreed with the Seismic Assessment Steering Group at concept design stage.
   3. Regularity
      At concept stage the architect is required to work with the structural engineer to conceive a structurally 'regular' building to improve seismic performance. The University requires building configurations with a continuous lateral load-resisting path with little or no irregularities and seeks buildings with regular distribution of mass and stiffness in plan and elevation. Where irregularities are unavoidable, during the concept design phase the design team must present to the University the reasons why such irregularities are unavoidable and the mitigations for review and approval.
   4. Limit states, ductility and displacements
      It is recognised that NZBC compliant buildings are designed to deliver life safety and basic amenity but not necessarily asset protection. At concept stage the design team is to agree Limit state performance, global ductility and building flexibility. When considering these parameters, secondary structure, façade, seismic restraint, and ceiling/partition performance and costs are to be considered.
      Generally, the University prefers low ductility systems that are detailed for ductility for capacity design principles, and low displacement designs.
   5. Low damage design
      Low damage design concepts and philosophy are to be considered by design teams and the University at briefing stage. Guidance on low damage design can be found in the MBIE low damage design project or the Ministry of Education requirement for Service Limit State 2 (SLS 2) load cases in the structural and geotechnical requirements document.
   6. Peer review
      All significant capital works projects require an independent peer review. The peer reviewer should be engaged early to agree the concept/preliminary design. The scope of the peer review is to include both a regulatory review to support building consent and conformance with the University's performance requirements.
   7. Non-structural elements including building services
      In addition to meeting mandatory requirements, a holistic approach to the restraint of services and non-structural elements is required from the design team. This is to ensure that efficient restraint provisions and seismic clearances are included from the onset and that for the completed building, damage and remedial work requirements following a seismic event, are reduced to a practicable minimum. To this end design teams shall, during the briefing and concept design stages, consider the following:
      • The location of main services routes/corridors, both horizontal and vertical and their coordination with structure and architecture to facilitate efficient (potentially common) restraint provisions and to ensure adequate spatial allowance including necessary seismic clearances.
      • How and from what structural elements, services and other non-structural elements will be supported and restrained.
      • How differential movement between services and penetrated elements can be reduced, especially where services penetrate fire separations, to reduce damage and remedial work requirements following a seismic event.
      • Ensuring that restraint provisions do not prevent the operation of antivibration measures and allow for necessary thermal expansion and contraction (of heating pipework for example).
      Restraint of building services and other key equipment shall meet the University's business continuity and asset protection requirements. Some University facilities will be “mission-critical” or have a post-disaster function dependent on the avoidance of serious damage, or the ability for timely return to service, of key building services plant and systems. For other facilities with high-value central plant or scientific/healthcare equipment, the consequence of serious equipment damage in a relatively minor seismic event will far outweigh the additional cost of restraints with enhanced seismic performance. The types of systems and equipment, and the appropriate serviceability limit states, shall be identified in the adopted project specific approach the Seismic Assessment Steering Group.

3. Seismic assessments

   Seismic assessments are to be of appropriate complexity and accuracy to fulfil the purpose. Seismic assessments must only be carried out by suitably qualified and trained CPEng structural engineers. When considering the type of assessment required figure 1 below should be used.

   The University would rather invest in appropriate building upgrade costs (including necessary design analysis) rather than sophisticated assessments that give a degree of accuracy not necessarily warranted at assessment stage.

   Figure 1.

   

   1. Assessment methodology
      Where assessments are in response to a territorial authority request for earthquake prone building status then the MBIE's chief executive methodology must be used (Red Book). In other situations, the University may require other methodologies to be used. Generally, this will be the NZSEE – Seismic Assessment of Existing Buildings (yellow book) but could be other recognised systems such as FEMA P58. Where a methodology outside of the MBIE guidelines is used this should be agreed in advance with the University.
   2. Initial Seismic Assessment (ISA)
      Where the consultant is confident that an ISA will pick up the issues/potential issues with a building and that the score is sufficiently accurate, ISA s maybe carried out. Noting figure 1 above the effort, cost and reliability of an ISA is a continuum. The consultant is to make efforts to access drawings when completing an ISA .
   3. Detailed Seismic Assessment (DSA)
      Where the building warrants a more thorough analysis, a DSA is to be undertaken.
   4. Peer review
      Seismic assessments that give unexpected results, indicate a score that triggers a significant occupancy review or indicate a significant re-strengthening project are to be considered to have preliminary status until they have been independently peer reviewed. An independent peer review shall be determined by the Director Campus Development or Director Property Services on a case-by-case basis.

4. Occupation assessment

   It is policy to act responsibly with respect to safety of life for students, staff, and visitors to the University. The University Seismic Policy requires buildings with a rating less than 20 per cent to have a risk assessment carried out. This risk assessment will inform decisions on occupancy. The occupancy/risk assessment is to include:

   1. Importance Level
      If the activities that occur within the building are driving the Importance Level (IL), then the IL can be reduced when undertaking an occupancy assessment. This is in order to undertake an occupancy assessment on life safety risk rather than post-disaster operations. This will be determined by the Seismic Programme Steering Group.
   2. Hazard description/collapse description
      The Occupation Assessment is to provide more commentary on the Assessment Outcome information required in both the ISA and DSA Assessment Summary Report Template obtained from the EQ-Assess website:
      • Templates – EQ-Assess
      Specifically identified structural weaknesses and locations are to be identified. The mode of failure and physical consequences statement is to describe how the weakness will fail, which areas will be affected by failure/falling objects and any likely subsequent failures/vulnerabilities as a result of this failure. This commentary is to be presented to the Seismic Assessment Steering Group in writing and also presented orally to ensure it is fully understood and allow questions so informed decisions to be made.
   3. Hazard management options
      In addition to hazard identification, the Occupation Assessment is to give options to control the hazard. The University wants to understand the options to ultimately eliminate the hazard but pragmatic short-term options that allow reduced or limited occupancy via engineering controls must be considered. Options may include staging of strengthening works to deal with issues that can be readily and quickly rectified, barricading off an area, limiting use of the building if that lowers the importance level or providing temporary propping/restraint to elements.
      The University requires this information to be presented in a table similar to below:
      
      

      Engineering statement of structural weaknesses and location	Mode of failure and physical consequence statement(s)	Hazard control options	Type of control (eliminate, substitute, engineering, etc.)
      Weakness 1
      Weakness 2

5. Seismic strengthening

   Where the seismic programme indicates strengthening is required on non-heritage buildings, the following guidance will be considered:

   1. Seismic strengthening work will be focused to provide the best overall improvements in life safety for students, staff, and visitors to the University. PSD will develop a programme to improve the seismic performance of the property portfolio. This will be endorsed by the Asset Management Committee and used to inform the Long-Term Capital Plan for the University.
   2. All strengthening work shall be considered in conjunction with the Strategic Asset Management Plan and Long-Term Capital Plan and other planned maintenance or alterations to the building.
   3. Seismic strengthening shall achieve at least 67 per cent NBS but aim for 100 per cent where practical. Exceptions to the 67 per cent NBS target can only be made in accordance with the University Seismic Policy.
   4. Strengthening shall address any severe structural weaknesses (SSW) as defined by the MBIE guidelines. Any proposed strengthening should not alter the load distribution such that other elements become critical at less than 67 per cent, or other Critical Structural Weaknesses (CSW) are introduced.
   5. Urgent strengthening work may target 34 per cent NBS as an interim strengthening step where appropriate.
   6. Where a significant capital investment is proposed, seismic strengthening shall be independently peer reviewed in accordance with the University Seismic Guidelines.
   7. Where a significant capital investment is proposed, a site-specific seismic hazard study should be undertaken to ensure future proofed outcome.
   8. Where building parts (e.g., chimneys, parapets, etc.) constitute a seismic risk, these may be strengthened or removed in isolation ahead of a comprehensive strengthening scheme. Guidance such as the MBIE “Securing parapets and facades on unreinforced masonry buildings” should be considered. Loads should be transferred to the primary lateral system in such upgrades. Where a staged upgrade is proposed, the consultant team shall ensure the University understands the short, and long-term performance.
   9. Where seismic strengthening is undertaken, a post completion DSA or “final” assessment will be provided by the Structural Engineer to the Project Manager, confirming the level to which the building was strengthened, noting this may differ from the design target.

6. Heritage buildings

   All heritage buildings are to have their heritage status considered in seismic strengthening designs.

   Strengthening designs should aim to minimise any potential heritage loss and should aim to create the least visual impact on the building. Technology or techniques yet to be developed may provide a better solution in the future.

   The durability of strengthening elements should match the likely life of the building where elements cannot be easily removed or replaced.

   Where the building is on the New Zealand Heritage List, the University shall engage a Heritage Architect to prepare a conservation report to inform the strengthening, with consideration given to likely strengthening techniques. A resource consent will likely be required in most cases.

   Where the building is identified as a “Character-Contributing Building” within the Dunedin City Council (DCC) District Plan (2GP) consultation with the DCC is required to confirm the protected building parts and approach to strengthening. A resource consent may be required.

7. References

   • FEMA P-58-1: Seismic Performance Assessment of Buildings, Volume 1 – Methodology, Second Edition
   • The Seismic Assessment of Existing Buildings – EQ-Assess
   • Dealing with earthquake-related health and safety risks: information for PCBUs and building owners – Worksafe

Related policies, procedures and forms

• Seismic Policy
• Design and Facility Standards (PDF)
• Post-Earthquake Building Assessment Guidelines

Contact for further information

If you have any queries regarding the content of these guidelines or need further clarification, contact:

Property Services Director
Email property.campusdevelopment.ea@otago.ac.nz