New damping devices help create more resilient buildings

QuakeCoRE Seminar – 20 April 2018: Kaley Crawford-Flett
March 25, 2018
QuakeCoRE Seminar – 18 May 2018: Joanne Stevenson
April 19, 2018

Associate Professor Geoff Rodgers and his team have developed two new innovative damping devices that absorb energy and help protect buildings from major damage during earthquakes. The devices will be attractive to building owners, because they are less likely than other devices to need to be replaced or reset after an earthquake, resulting in both time and cost savings.

Current designs for earthquake-safe buildings feature “sacrificial structures” that will absorb energy and prevent building collapse. This type of engineering is designed to save lives, but it usually results in significant structural damage that is expensive and time-consuming to fix or replace, often leading to widespread demolition as seen after the 2010-2011 Canterbury Earthquake Sequence.

The two damping devices are uniquely designed to handle different building structures and types of ground shaking. The first design, an extrusion damper, pushes lead through a chamber to absorb and dissipate energy. Importantly, the process is completely reversible so after ground shaking, the device does not need to be reset.

The Forte Health building in Christchurch has already incorporated this device, and an ongoing project will use them in a community housing project in San Francisco. Geoff is also currently involved in a project to test the devices in a two-storey reinforced concrete rocking-wall structure. This project is a collaboration between QuakeCoRE and the International Joint Research Laboratory for Earthquake Engineering (ILEE) at Tongji University in Shanghai, funded by the Ministry of Business, Innovation and Employment (MBIE).

The second device, called Displacement and Direction Dependent Viscous Dampers (or D3 Dampers for short), uses a design with two pistons, one-way valves and a stepped cylinder wall to create different flow paths depending on which direction the building is being displaced. This response is better than previous similar devices because this D3 Damper responds automatically based on the rules of physics, rather than requiring external computation and sensors. The complex computation required with other devices and corresponding concerns about robustness has created a major barrier to their use in construction projects in the past.

Geoff and his team are also investigating how an existing high stiffness Ring-Spring technology could be used within the D3 Damper. These springs use a different type of energy dissipation to the damper, so used in combination, they could create a device that would be effective regardless of the type of ground shaking that occurs.

The team’s focus is now on refining the D3 Damper design, based on the results of shake-table testing. They are also doing structural modelling to create guidelines to help practitioners use both technologies in the field.

Showcasing the importance of this work, in 2017 Geoff was awarded the Kiwi Innovation Network (KiwiNet) Norman FB Barry Foundation’s Emerging Innovator Award, as well as the Royal Society Te Apārangi Early Career Research Excellence Award for Technology, Applied Science and Engineering. These awards recognise the significant impact of Geoff’s work in the field of earthquake engineering, especially in the design and engineering of earthquake-resilient structures.

Read more about research highlights in the 2017 QuakeCoRE Annual Report.

 

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