Tropical Cyclone Larry: Estimation of wind field and assessment of building damage

Abstract

Tropical Cyclone Larry made landfall on 20 March 2006 near Innisfail, causing signifi cant damage to buildings in the surrounding areas. This paper is based on the field survey and assessment of the performance of buildings, which experienced severe winds in the Innisfail region during Tropical Cyclone Larry. The peak gust wind speeds in the study area are estimated at 50 to 65 m/s, which is less than the region’s current design wind speed. Damage to the housing stock was estimated at about 20% (not including water ingress). Contemporary housing fared considerably better than older housing, refl ecting marked improvement of construction detailing and better structural condition, and satisfactory performance of relevant standards. Failure of roller doors, loss of roof battens when fastened to rafters with one or two nails, and loss of rafters or trusses when anchored to top plates with skew nails only, were common. Structural component failures of under-designed cold-formed steel sheds and garages were also widespread. Construction details used in houses on or near hill-tops need to refl ect the higher wind speed caused by topographic effects.