Who is Responsible for Ensuring Interior Seismic Design Complies with Code?
Matt Bishop
Engineering the Future AEC Firm | Strategy & Systems for Smarter Interiors | PRENGUIN + Brevity
Why seismic responsibility is difficult to pin-point:
Where the responsibility lies for seismic design is not very clear. At a high level, the responsibilities naturally lie with the person who will suffer loss in a disaster, which is ultimately the client, asset owner or tenant.
However, the quality of construction, and therefore the seismic design, is regulated through federal, state and local governments. As the regulators take on the responsibility for certifying designs that meet the regulations, they are also liable if the design they certify isn't compliant.
To confuse the matter further, in a Design and Construct contract the builder or subcontractor may become contractually liable for designing and building compliant interiors.
Where does the main confusion lie?
The main confusion lies around the motivations for seismic design as they are separated from the responsibilities. The building code requirements are set at a level where seismically compliant interiors will be able to withstand an earthquake that has a 10% chance of happening over 50 years. 50 years is a time period that is aligned with the life of the asset. The asset owner therefore has a strong motivation to prevent loss due to this 1/10 risk.
However, the builder or subcontractor will be very unlucky if an earthquake occurs during the construction schedule. The motivation of the builder is contractual rather than loss driven and it is their primary responsibility, driven by the inclusion of the earthquake standards (AS 1170.4) in the building codes.
What is the contractual obligation for seismic design?
Seismic design responsibilities will typically transfer to the contractor through the inclusion of a requirement like, "All construction to comply with current building code", or maybe more specifically "All interior building elements to comply with AS 1170.4".
A broad contractual obligation like this leaves room for interpretation. But ultimately, what the regulator accepts as a compliant design will be good enough for the contract. However yet again, we have conflicting motivations. The motivation of the contractor is to optimise the seismic design to achieve best value, and the motivation of the regulator is to ensure that the seismic design is carried out by competent persons with adequate insurance. This ensures the regulator will not be liable for any design failures.
At the end of the day, the asset owner still owns the risk
The seismic regulations are based on scientific observations of past events. We will get a design level earthquake every 50 years with a 10% probability. But until we get that event, the seismic systems will remain dormant and do practically nothing. It is the asset owner that is in the best position to understand this long-tail risk and plan accordingly.
If you'd like to ask me any questions about the above, or would like to discuss an existing project, feel free to get in touch.
Matt Bishop.
Efficient Seismic Bracing and Suspension for Building Services
5yIn Australia the responsibility has to come all the way from the top, ie the person paying for the project needs to be onboard and willing to pay for protecting the interior against earthquake loading. And since “there are no earthquakes in Australia” the building owner would not have a clue so it is the responsibility of the consulting engineer on the client’s side to advise them of the BCA requirements in order for them to make sufficient allowances in their budget to pay people like us. If there is no money to pay for it up front then everyone will try to wiggle out of it!
Building(v) resilient facilities for the rigours of BAU & UNUSUAL (disruption). Topics: Importance Levels, b. services & arch. - Seismic, passive & IL4 post-disaster functional recovery (Special Study)
5yWow, look at this for exciting times of open discussion... better to have this discussion now than post-event when the blame game begins and a Royal Commission called... here's my take on applying Section 8 in AU: The NCC 2019 Volume 1 calls up 'AS1170.4 as appropriate' (but in total) under Part B1 Stuctural Provisions B1.2 Deternination of individual actions (c) (iii). There is no risk assessment here, you follow the standard. AS1170.4 is an amazing read when you start getting into this stuff, but cutting it short, read: 2.1 General - 'shall be appropriate for the type of structure or element, it's intended use, design working life and exposure to earthquake shaking'... hinting here that we have a design (maybe risk assessment) approach coming, similar to the new NCC2019 Amendment 1 'Building Complexity Decision Process' approach. 2.2 Design Procedure - lots and lots of stuff, even times when the NZS1170.5 should apply on AU soil and considerations for soil Ee... but I digress: Grab all of your project data listed and see Figure 2.2 and follow the flow diagram in Figure 2.2... Domestic structure up to 8.5, go direct to Appendix A, otherwise start adventure again as IL2. IL2, 3 & 4, follow the adventure and see which Earthquake Design Category (EDC) you end up at... EDC 1 - minimal acceleration calculation requirements for parts and components under Section 5.3... but Section 5.2 still applies the structure and non-structural connection and there's still a few specially worded sections; this is the work of some brilliant minds actually, and others. EDC 2 - some folks mistake this to be an advantage over EDC 3 for Parts and Components, but Section 8 still applies with one minor reduction: 'parts and components of non-brittle construction'. This usually doesn't change much (to my limited experience), unless an engineering opinion comes along with a rubber stamp, limited Specific Engineering Design knowledge (insert joke about experience versus knowledge here), and you've got yourself a Defects Liability period. EDC 3... go directly to Section 8, Do not pass-out and Collect yourself as it's going to be fine. Section 8, the oasis at the end of this desert journey... 'Non-structural parts and components and their fastenings, as listed in Clause 8.1.4, shall be design for horizontal and verfical earthquake forces as defined in Clauses 8.1.2 and 8.1.3, and accommodate the design inter-story drift.' (Insert drink break here). Okay... now the work of a Seismic Design Engineer starts, such as: BVT, KCL, Eurofast, Kusch Group, and others I can't rattle off the top of my head right now. Words of warning... Cheap or free design - 2 possible outcomes 1. Non-compliant design due to cherry picking of standards and calculations failing scrutiny. 2. Over specification of building materials and therefore cost of product/labour/time. IL4 buildings - 'require a special study to demonstrate IL4 structures shall remain serviceable for immediate use following the design event for IL2 structures (1in500 year event) Exemptions under 8.1.4 (xviii) - do not apply to IL4 without SPECIAL STUDY do not apply to the systems listed above (so read the entire 8.1.4 (b) carefully, I know the Certifiers/Surveyors will be. Okay... time for another beer.... Need to talk seismic, give me a call... especially product development, project documentation preparation, specification sections and avoiding seismic requirements for special circumstances (retrofits, older structures), etc.
retired from providing APFS services - but still publisher & editor technical publications and advisor re building services & compliance
5yIn Australia NCC 2019 BCA vol.1 BP1.1 Structural reliability. (b)(iv) earthquake action MUST be considered. Engineering Associations (Engineers Australia, AMCA, AIRAH, etc) in Australia endorse the view that a risk assessment should be conducted and that utilisation of the earthquake hazard map can be used to clarify IF Seismic restraints / cross bracing is necessary. Our view is that in NSW, Seismic Restraint would be a requirement in the Newcastle Zone, and Crookwell Zone as detailed in the Seismic Hazard map from AS1170.4, whilst where no earthquake risk is indicated such as within the Sydney basin: No seismic restraints would be a necessary requirement. Whilst it is up to the Principal Certifier to determine if seismic restraints are required and they should always seek clarification from the project structural consultant, if they do so for a nil-risk hazard area, then they are opening themselves to litigation and cost recovery by the owner/ developer.
Director at Eurofast Global Making you "Safer with Seismic"
5yDavid Chandler OAM
Director at: Passive Fire Consulting CFSP: F054929A
5yI expect theirs an element of due diligence to understand what is contractted & built is compliant by builders & certifiers. It's the lack of understanding & knowledge by builders writing scopes & issuing contracts & further lack of contractors as the fundamental issue. This is then exasperated when the view is as noted in this post which results in a focus to write clauses in contracts to simply mitigate any liability. All focus on washing their hands then understanding and doing the job write. The mentality is rife throughout many facets of the construction industry. The question is how do you fix it?