Experimental investigation of aluminum square and rectangular beams with circular perforations

Both three-point and four-point bending tests were conducted on aluminum square and rectangular beams with circular perforations. Test specimens consist of 9 perforated and 4 imperforated beams subjected to gradient and constant bending moment. The extrusion of 6061-T6 and 6063-T5 heat-treated aluminum alloys were used to manufacture square and rectangular hollow sections (SHS and RHS), respectively. The evaluation of the strength and behavior of aluminum square and rectangular beams focuses on the effects of the aspect ratio, the ratio of plate width, the ratio of plate slenderness, the ratio of perforation dimension and the number of perforations. Test results including the ultimate strengths, failure modes of local and flexural buckling failure, bending moment versus curvature curves and strain distributions along the circular perforations are all reported, which were employed to assess the suitability of the current design specifications. The comparison of test strengths with design strengths shows that the modified DSM for aluminum structural members is somewhat conservative with the lowest value of COV, whereas other design specifications for cold-formed steel and aluminum structural members are quite conservative with comparatively high value of COV. It is also demonstrated from the comparison that the perforated sections close to the mid-span of the beams are the critical section under gradient and constant bending moment. In addition, the comparison of test strengths with design strengths also reveals that the current design rules for perforated cold-formed steel and aluminum structural members are all conservative, in which North American Specifications (NAS) for perforated cold-formed steel structural members are generally appropriate with the lowest value of COV.