title: Web Crippling Behaviour and Design of Roll-formed Aluminium Lipped Channel Sections
Creators: name: Alsanat, Husam R
Publisher: name: Griffith University
Year: 2019
Subjects: subject: aluminium alloy members
subject: bearing failure
subject: web crippling
subject: aluminium lipped channel sections

description: The use of aluminium alloy members in building construction has increased worldwide in recent years, especially in areas with adverse conditions such as severe industrial and marine environments. Aluminium members can be used in the structural systems of residential, industrial and commercial buildings as purlins, floor joists, rafters, decks and wall studs. corrosion resistance, lightweight nature and high strength-to-weight ratio are some of the important advantages of aluminium members. Despite of these advantages, the elastic modulus of aluminium is only one-third that of steel, making aluminium members highly susceptible to various failure modes including bearing failure. This bearing failure, commonly known as web crippling, is one of the critical failure modes of thin-walled members including lipped channel sections that are unstiffened against flexural loads. To date, only a limited amount of research studies has been conducted to investigate the web crippling failure phenomenon for aluminium structural members, and no research has been carried out on the web crippling behaviour of roll-formed aluminium lipped channel sections. Hence, this research aims to conduct an experimental study using the new American Iron and Steel Institute (AISI) S909 test procedures and associated numerical studies for lipped channel sections under four loading conditions: End-Two- Flange (ETF), Interior-Two-Flange (ITF), End-One-Flange (EOF) and Interior-One- Flange (IOF). This research also considers both unfastened (flanges not connected to the support) and fastened (flanges connected to the support) conditions to cover all possible restrain scenarios in the real-world applications. Following extensive experimental tests, a series of finite element analyses (FEA) were performed to develop precise numerical models of all the tested aluminium lipped channel sections. The general-purpose software ABAQUS, with quasi-static explicit solver, was employed for this study since contact and large deformations were involved. The models were validated using the experimental results and a good agreement was achieved in terms of ultimate failure strengths, load-deflection responses and failure modes. Subsequently, the validated models were used as a basis to conduct a detailed parametric study to investigate a range of commonly used aluminium lipped channel sections with varying thicknesses, heights, inside bent radii, bearing lengths and aluminium alloy grades. The results acquired from this research were compared with the nominal web crippling strengths predicted by the currently available design rules recommended by the Australian, European and American Standards. As a result of the comparisons, weaknesses in the current design standards were identified and suitable modifications were made based on the experimental and numerical results to accurately predict the web crippling capacities of aluminium lipped channel sections. Further, a suitable Direct Strength Method (DSM)-based design approach was developed in this study and associated equations were established to accurately predict the elastic bucking and plastic loads of aluminium lipped channel sections under web crippling action.