Mind the Gap: Code-Based Minimum Performance vs. Public Expectations - the New Zealand Experience

Paul Campbell
Technical Director
WSP, Auckland

Traditionally, seismic design has focused only on protecting human life and enabling evacuation, as opposed to asset protection. Recent experience from the Canterbury and Kaikōura, New Zealand earthquake sequences in 2010 and 2016, respectively, has shown there is a gap between what performance engineers consider during seismic design and what clients and the public believe engineers deliver. Why does this matter? With buildings becoming taller in areas of high seismicity, what happens to cities, communities and our urban habitat when a large earthquake strikes?

Recent research has focused on low-damage building technologies, as a way forward for building designers to implement damage-reduction measures into seismic design. Most research is concentrated on new structural systems or devices to improve building performance. However, not all the proposed systems will deliver low-damage performance, in the broadest sense. What is needed is a “Low-Damage Design” (NZ) or “Functional Recovery” (USA) philosophy that aims to reduce the extent of damage that a building suffers during an earthquake. The aim of this philosophy is to limit the economic and social impact of seismic damage by reducing the cost of repairs and reducing the length of time to repair and re-occupy. Case studies are discussed to illustrate the need to think about performance objectives that can be measured, versus following code-compliant designs by default. Consideration is given to criteria that should be part of the agreed performance conversation between designer and client, with the aim of ensuring that the credibility of the design profession is preserved.

Accompanying PowerPoint Presentation