Published works

Tropical Cyclone Debbie (TC Debbie) was classified by the Bureau of Meteorology (BoM) as a Category 4 cyclone and crossed the Queensland coast north east of Airlie Beach around midday on Tuesday 28 March 2017.

Before the event, the Cyclone Testing Station (CTS) deployed six mobile anemometers (SWIRLnet) in the area between Ayr and Proserpine. After the event, CTS teams investigated the performance of houses; larger residential structures such as apartments, strata properties and resort accommodation; commercial and public buildings; and sheds. The study area included the communities of Bowen, Proserpine, Airlie Beach, Hamilton Island, Dingo Beach, Wilson’s Beach and Conway Beach. A wind field was developed using CTS and BoM anemometer data and showed that buildings within the study area experienced wind speeds lower than their relevant design wind speed.

CTS teams assessed the causes of damage to buildings from wind, wind-driven rainwater and storm surge. Inadequate tie-down details between battens and rafters or trusses, and between the roof structure and walls caused many of the structural failures in buildings constructed before the 1980s. Tie-down connections between roof structure and walls that had been inappropriately detailed also failed on some recently constructed buildings. Connections between verandah beams and posts on some buildings with larger verandahs also failed.  

This study confirmed the findings of previous damage investigations concerning the vulnerability of: windows with inadequate fixings, window and door furniture; poorly fixed flashings, gutters and soffit linings; large access doors that had not been strengthened so that they complied with AS/NZS4505; lightweight sheds; and fences.

Many occupants of newer buildings reported significant damage from wind-driven rain entering through windows and doors or under flashings even though there was no structural damage to the building. Many people reported that they mopped up water in front of windward wall windows during periods of maximum winds, which exposed them to risk of injury. Further research is required to improve performance of building elements that leak during high winds.

The storm tide generated during TC Debbie was lower than predicted because the cyclone crossed the coast after high tide. Lower-lying buildings in Wilson Beach were inundated to a height of up to 1.1 m causing damage to wall linings, built-in cupboards, floor coverings and contents. In some cases, wave action broke cladding elements and windows. Wave action and scour undercut footings in some buildings on Hamilton Island and Wilson Beach. 

The report provides recommendations to improve the performance of building structure and cladding systems including: adequate detailing for roof to wall connections; improved fixing of flashings, retrofitting options for older buildings; improvements in windows and door furniture under repeated wind loads; and revision of storm surge guidelines.