International Earthquake Standards

International Earthquake Standards and Compliance

An important aspect of compliance is a quantifiable paper trail.
All aspects of seismic restraint and gravity support details are interdependent, and their design and attachment to the structure should not be separated.
It was interesting to read in September Insight an article “Changing International Earthquake Standards”.
The article fails to caution the reader when it comes to using new so called performance based standards for post installed concrete anchors referred to in the article as complying with European Technical Association (ETA) seismic codes.

The New Zealand Building Code requires all building elements to have a low probability of failure when exposed to loads likely to be experienced within their lifetime (Clause B1 Structure).
Within the NZBC B1/VM1 there is reference to NZS 3101 Part 1. Concrete Structures; 2006. – The Design of Concrete Structures. Clause 17.5.5 includes “Post-installed mechanical anchors intended to resist seismic actions shall have passed the simulated seismic test of ACI 355.2.”

Ceilings should be designed in accordance with two standards taken together, NZS 1170.5:2004 Structural Design Actions – Part 5: Earthquake Actions; and AS/NZS 2785:2000 Suspended Ceilings – Design and Installation, as the means for meeting Clause B1 of the NZBC.

If contractors wish to use concrete anchors or in fact any anchor that is not qualified within specific performance clauses of the New Zealand Building Code and New Zealand Standards, the anchors are deemed to be a “Departure from the Standards”. This includes concrete anchors and chemical anchors qualified exclusively to the ETA seismic codes.
The Building Control Authority (BCA) needs to be notified and their acceptance in writing should be required for the departure. The best time for notification is when the contractor submits a PS1 and within this document the contractor would list and documented seismic assessments and qualification of the items as a “Departure from the Standards”. The BCA will need to be satisfied on reasonable grounds that performance of anchors that have seismic qualifications will be adequate in contributing to a code complying design.

An exception is when proprietary anchors outside the standards are included for use within tender/contract specifications for specific projects but this would still require documentation if the PS4 only references a standard.

Contractors make consumable procurement decisions every day – the reason for this short note is to make contractors aware that a decision today has a long lasting effect on exposure to risk. Make sure your risk exposure is mitigated and if you or your seismic specialist decide to go outside the standard, make sure you get an early engagement and sign off with the Building Control Authority.

Terry Johnson
Reveal Seismics Limited.

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