What’s the problem?
Post-EQ damage observations:
Performance of Non-Structural Elements (NSEs) in September 2010 and February 2011 earthquakes raised a concern. Considerable repair and replacement costs were incurred as well as great financial loss due to downtime. Mw 6.5 Seddon earthquake in August 2013 was only a confirmation of the issue.
How do NSEs work?: Improving our understanding of the behavior of the systems, their capacity, demands and interactions with other NSEs and structure through experimental work seems to be the first step into the prevention of loss incurred by NSEs.
Inconsistency in recommendations: Having had the opportunity to interact with ceiling industry, manufacturers and contractors, it was noticed that there are concerns about the consistency of the presented work and enforcement of the minimum requirements.
A more profound understanding of the performance of the system and the transfer of demands can be beneficial in designing for the right limit state to minimise damage. It can also be used to facilitate a better estimation of loss incurred by NSEs.
Having a clear and comprehensive design and installation checklist leads to an easier and more consistent design procedure.
Providing consistency in design and installation based on the capacity of the system makes it easier to evaluate the job delivered. It also facilitates fair and equal competition among various manufacturers and tenderers.
Providing a system that addresses needs of common practice as well as special cases.
1) Providing analytical fragility input for estimation of loss incurred by NSEs
Schematic of load path on perimeter-fixed ceiling
Analytical fragility curve for perimeter-fixed ceiling
Allowable main tee side length vs. ceiling acceleration with 16% failure probability for various ceiling weights
2) Simplified estimate of demand and capacity in suspended ceilings backed up with experimental results from shake table tests
Shake table and test frame in UC Structures Lab
Comparison between predicted and measured force in ceiling grid members in perimeter-fixed ceiling
3) Testing a proposed low-damage system: Isolating ceiling from the structure
Isolation foam placed in and filling the perimeter gap
Relationship between frequency and amplitude of input acceleration and the peak displacement in fully-floating ceiling.
4) Integration and compatibility with other NSEs: Shake table tests on suspended ceiling & low-damage drywall partitions
Exterior and interior views of the ceiling and drywall specimen
5) Design and installation recommendation leading to a consistent practice
Ceiling & wall industry – Designers – Tenderers – Clients
Other researchers working in related areas
The research project is funded by the Natural Hazard Research Platform and experiments were conducted in the University of Canterbury Structures lab. The interactions and collaboration with UCQC has provided a great opportunity in terms of supervision and experimental insight. The authors would also like to acknowledge the collaborations with USG Boral and GIB for providing technical support as well as installation assistance.