Shear Behaviour and Design of Roll-Formed Aluminium Lipped Channel Sections With and Without Web Openings

Abstract

Recently, the use of aluminium sections as primary load bearing members has increased significantly in the building industry. Aluminium as a new constructional material has several advantages in building structures including corrosion resistance, durability, high strength-to-weight ratio, reduced cost of transportation and ease of erection and fabrication. The popularity of aluminium structures has attracted the attention regarding the efficiency and design of many sections, and roll-formed aluminium lipped channel beam (LCB) is one of these commonly used sections. However, aluminium LCBs are inclined to shear buckling failure due to its increased web slenderness and low elastic modulus compared to steel which has raised the issue about the failure of these sections. Hence detailed experimental and numerical studies were conducted to investigate the shear behaviour of roll-formed aluminium LCBs, and to verify the current design rules to accurately predict the shear capacities. A total of 28 shear tests has been carried out using commonly available ten different aluminium lipped channel beams with varying heights and thicknesses to investigate the shear behaviour of roll-formed aluminium LCBs. The test specimens were loaded at mid-span at the shear centre until failure. Comparative study was also required between the obtained results from this investigation in order to propose improved design rules. Finite element models of aluminium LCBs were then developed and validated with test results. A detailed parametric study including 120 models was also undertaken with different sections, web slenderness, aluminium grades and aspect ratios to obtain the shear strengths and shear buckling characteristics of aluminium LCBs. The ultimate shear capacities of aluminium LCBs obtained from the tests and finite element analyses (FEA) were compared with the current shear design rules of Australian/New Zealand Standard and Eurocode for both aluminium structures and cold-formed structures as well as direct strength method (DSM). The comparison showed that these current shear design rules are not suitable to predict the shear strengths of roll-formed aluminium LCBs. Hence new design rules were proposed in this study to accurately predict the shear capacities of roll-formed aluminium LCBs. Web openings are incorporated in these sections to accommodate building services when they are used as beams. Hence, experimental and numerical studies were also conducted in this research to investigate the shear behaviour of these roll-formed aluminium LCBs with web openings. An aspect ratio of one was considered in this study. A total of 17 tests were conducted to investigate the shear behaviour of aluminium LCBs with circular web openings using three-point loading arrangement. Finite element models were also developed with appropriate loading and boundary conditions and validated using the experimental results. A detailed parametric study including 204 models was then undertaken using the currently available roll-formed aluminium LCBs with different thicknesses, grades and web opening sizes. The ultimate shear capacities and the shear capacity reduction factors obtained from the tests and finite element analyses were compared with the currently available design rules.