Fatigue Life Analysis for Structures

Fatigue Life Analysis for Structures

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.

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.

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 analysed the load-effect versus number of cycles for a number of key load effects for the steel roof structure.

Case Study: Steel Frame for Forsyth Barr Stadium, Dunedin, New Zealand

This stadium, located in Dunedin, New Zealand was used as part of the 2011 Rugby World Cup. A wind tunnel study was undertaken to determine the design pressures on the structure and cladding for this stadium. The structural loads 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 framing structure. The structural consultant engaged WINDTECH Consultants to undertake a load-cycle analysis in the form of load-effect versus number of cycles for a number of key load effects. This in turn was used to undertake a detailed stress-cycle modelling for the connection details associated with these members.

A design was presented to ensure the fatigue life of the various joints was satisfactory.