Fatigue Life Analysis for Structures | Wind Engineering

Fatigue Life Analysis for Structures
Introduction
Large steel-framed structures are particularly prone to fatigue failure due to the ability of small fractures to quickly propagate into the structural element. Such structures can eventually fail under repetitive loads that are significantly below the ultimate strength capacity of the structure at the time of construction. WINDTECH Consultants can undertake an analysis of structures of this kind to estimate the fatigue life of the key joints within the structure. The accuracy of this estimate can be substantially enhanced if a wind tunnel study is also carried out and reliable wind climate data is available. WINDTECH Consultants can also provide load-cycle data to assist the structural consultant to undertake a study of the fatigue life.	WINDTECH Consultants analysed the fatigue life for the various key connections within the steel roof fin structure on top of this 300m tall building in the Middle East.

Case Study: 30m high fin on the roof of a 300m tall tower building
This tower building in the Middle East has a 30m high roof fin (refer to the image). The roof fin is of steel-framed construction with welded members and a bolted footing. A fatigue life analysis was carried out for various joint types in the structure. This required an analysis of the local wind climate data and inputs from the structural consultant in terms of the relationship between the applied pressure and the stress experienced at various joints. A design was presented to ensure the fatigue life of the various joints was satisfactory.
	WINDTECH Consultants determined the stress/ cycle loading for key nodes within this steel framed structure in New Zealand.
Case Study: Otago Stadium, Dunedin, New Zealand
A wind tunnel study was carried out of the design pressures on the structure and cladding for this building. The structural load study was based on the Load Response Correlation technique which has resulted in a light and efficient structure made of ETFE facade and roof cushions supported by a predominantly steel structure. The structural consultant engaged WINDTECH Consultants to undertake a form of load-cycle analysis in the form of load-effect vs number of cycles for a number of key load effects. This in turn was used to undertake detailed stress-cycle modelling for the connection details associated with those members. [ refer to supplied photo of Otago showing model in the wind tunnel]

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