Shake-Ups and Wake-Ups: Surprise Learnings from the 2010-11 Earthquakes
27 June 2022
Research into the earthquake performance of buildings at the University of Canterbury has led the field in an unexpected new direction. Dr Rajesh Dhakal, Professor of Structural and Earthquake Engineering at UC, reveals the new angle on building resilience and explains why it matters.
Professor Rajesh Dhakal
The 2010-11 Canterbury Earthquake Sequence took the whole country by surprise. As leading structural and earthquake engineering experts flooded to the region to study what had happened, UC’s Civil and Natural Resource Engineering (CNRE) department became the powerhouse for leading research.
The overarching focus of research at CNRE was on understanding, and learning from, the way land, infrastructure and buildings performed in earthquakes. Given the tragic and extensive failure of Christchurch’s buildings, there was a particular emphasis put on assessing buildings’ resilience. This examination went beyond the expected contribution of a building skeleton in providing strength and stiffness, to the surprisingly significant role played by non-structural elements.
“If I am asked to identify a positive from the Canterbury earthquakes, I will put forward the widespread realisation of how important the non-structural elements – such as fit outs, partitioning walls, cladding panels, ceilings, sprinklers, glazing, plumbing, electrical, HVAC systems and building contents – are for ensuring the continuous functionality of buildings,” says Professor Rajesh Dhakal.
$40 billion in insurance claims resulted from the Canterbury earthquakes, a substantial percentage of which were for damages to non-structural elements. Suddenly, the earthquake performance of fit-outs, dry wall and sprinkler systems were thrown into the spotlight, forming a new area focus for the structural and earthquake engineering community. “80% of a building’s value comes from its non-structural elements” says Dr Dhakal.
Another surprise factor was how seismic losses actually accrue. In most non-residential buildings, business interruption costs due to a building’s ‘downtime’ far exceeded the cost of repairs. The financial penalties caused by buildings becoming non-functional due to non-structural damage is massive.
In an example of this phenomenon, the BNZ building in Wellington was closed for multiple weeks after the 2013 Seddon earthquake, which was not a severe earthquake by any measure. The primary reason for the closure? Damage to ceilings and sprinkler systems.
So while damaged non-structural elements may not cause a building to fall to the ground, the financial cost is hugely significant. Furthermore, it’s a cost which, until now, has been largely ignored.
This revelation, spurred by research undertaken at UC’s Civil and Natural Resource Engineering department, has made waves worldwide. The International Association of SPONSE (www.sponse.eu) provides a platform for knowledge-sharing and thought leadership around the Seismic Performance Of Non-Structural Elements (SPONSE). This global organisation of engineers, architects, manufacturers, insurers, builders, planners, public officials and social scientists is currently led by none other than UC’s Dr Dhakal, as President.
“All stakeholders now realise that the performance of non-structural elements is a priority for the earthquake engineering community to solve. We are leading the world with the research we’re doing at the University of Canterbury,” says Dr Dhakal.
Professors Rajesh Dhakal and Tim Sullivan and their team at CNRE are involved in a wide range of research projects which aim to understand the limitations of, and improve on, the current design and installation practices of non-structural elements.
Dr Dhakal is leading the Non-Structural Elements theme of the $12M Building Innovation Partnership (BIP) project, co-funded by MBIE and industry. One of the key priorities of the project is to understand the ways current design, fabrication and installation practices lead to poor seismic performance. It also aims to improve design methods for non-structural components and develop innovative low-damage solutions for non-structural components.
As a part of the BIP project, PhD student Mohammed Rashid is investigating seismic performance of fire sprinkler systems and looking into how different configurations alter their response in earthquakes and affect consequential damage. Another PhD student, Fransiscus Arifin, is investigating how earthquake-induced shaking affects the water-tightness of window glazing. Similarly, PhD student Jitendra Bhatta’s research has developed innovative low-damage versions of internal drywall partitions and external precast cladding panels.
The Canterbury earthquakes shook New Zealand out what can only be described as a state of complacency with regards to natural disasters and the costs they impose, both economically and socially. Research undertaken over the past 11 years has generated new and unexpected learnings, which are now setting changes into motion.
"Although we had traditionally focused on how the structural skeleton behaves in an earthquake, we’re now shifting focus to the bigger issue – the millions of dollars lost when fit outs aren’t adequately secured or appropriately designed,” says Rajesh. “Damage to non-structural components in buildings is the biggest contributor to the financial loss and business downtime following major earthquakes. Avoiding severe damage to non-structural elements in buildings is now, rightly, a priority.”
Professor Tim Sullivan
Timothy Sullivan timothy.sullivan@canterbury.ac.nz
Rajesh Dhakal rajesh.dhakal@canterbury.ac.nz
Media contact:
- Email: media@canterbury.ac.nz Ph: (03) 369 3631 or 027 503 0168
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