Who is Responsible for Ensuring Interior Seismic Design Complies with Code?

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 have any questions about the above, or would like to discuss an existing project, feel free to get in touch by leaving your information below, or by calling us. - Matt Bishop, Managing Director, BVT.

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