Quake simulations put walls and ceilings to the test
On January 7th 1994, the San Fernando valley region of Los Angeles, California was hit by a devastating ‘blind thrust’ earthquake, with a moment magnitude of 6.7. The ‘Northridge Earthquake’, as it became known, produced the highest ground acceleration ever recorded instrumentally in an urban area of North America. The quake killed 57 people, injured over 5,000 more and caused property damage in the vicinity of $20 billion.
Fast-forward to 2015 and a research team at the University of Canterbury are five years into an extensive programme for the development of low damage solutions for non-structural elements – typically partition walls and suspended ceilings. By using a shake table simulation, they have been able to replicate North Ridge’s earthquake sequence, harnessing the same shaking motion as the recorded ground motion at the time of the quake – and put their experimental non-load bearing partition walls up to the force.
The room-sized steel frame test setup allows the performance of ceiling systems and low damage drywalls to be put to the test against the simulated force of an earthquake. The tests have yielded excellent results, demonstrating very good seismic performance of these walls and combined suspended ceiling grids.
See the shake table in action:
The research is being carried out by PhD candidate Atefeh Pourali, under the supervision of Rajesh Shakel, Greg Macrae and Sahin Tasligedik. During the five years since the programme began, the Canterbury earthquake series occurred, further signifying the poor performance of non-structural systems. As Atefeh says, the research could have significant ramifications in the event of more earthquakes.
“The main objective of these experiments is to improve the current condition of non-structural elements designed and constructed in buildings and reduce the potential for fairly significant financial loss caused by damage in any future events.”
Several industry partners, including USG Boral NZ and Winstone Wallboards Ltd, are backing the team and have collaborated significantly, helping with the supply of ceiling materials and gypsum plasterboard respectively. Hans Gerlich of Winstone Wallboards has been involved with the project and is seeing positive results.
“I was surprised that sliding inner frame connection details and vertical relief joints between plasterboard linings can significantly limit damage and improve the seismic performance of non-structural walls.”
Quake Centre Board Member John Burden, who is also Project Director Infrastructure for The Fletcher Construction Company Ltd, says that a lot of the success of the research project has been down to the strong relationships that the Quake Centre has developed with industry partners.
“The relationship between Winstone Wallboards and the Centre allowed the research team to draw from specialist industry knowledge, and to produce meaningful test results and practical and commercially applicable solutions. It works two ways, as it has meant that Winstone Wallboards could answer questions from designers on these non-structural elements, even before the project's results were published."
John says the success of the project has already created more opportunities to partner.
“Winstone Wallboards has found the Quake Centre great to work with and are seeking out more opportunities for collaboration, including another project which is already underway.”
Watch more footage of the simulations below...