Improving local stability of aluminium profile with low-modulus stiffeners: Experimental and numerical web buckling analysis

Abstract

Facades of modern buildings are the frequent objects of application of aluminium profiles. Reduction of the self-weight governs the development of those structures—a decrease of the web thickness and an increase of the profile height ensure the required flexural resistance of the building components. However, such an optimisation process makes these structural elements vulnerable to web crippling. The findings reported in the literature linked the solution of the buckling problem to the application of low-modulus filler material to stabilise the web’s deformations and increase the load-bearing capacity and the deformation energy absorption of thin-walled composite elements. This study experimentally illustrates the above solution, developing an efficient hybrid cross-section. A hollow section aluminium profile (mullion) available on the market was the subject of the three-point bending and compression tests. Low-modulus polymer stiffeners produced using a 3D printing technique strengthened the composite samples developed in this study. The infill density of the printed polymer was the variable of the research. A 10% printing density was the minimum value used in the tests. The adhesively bonded stiffeners, even of the minimum infill density, doubled the flexural resistance of the profiles. A local buckling caused the failure of the reference specimens, having no internal infill. On the contrary, the aluminium breakage resulting from the strengthened samples’ tests indicates an efficient use of materials. A simplified numerical linear buckling analysis helps to explain the stiffeners’ effect.