Experimental Investigations on Web Crippling Failure Modes of Aluminum Hollow and Composite Tubes

In order to study the web-crippling behavior of aluminum hollow section subjected to concentrated load, sixteen aluminum hollow tubes with different loading conditions, bearing length and web slenderness ratios were tested. This paper also discussed a method to improve the web crippling strength of the aluminum hollow sections by infilling the mortar as composite section, and four aluminum composite sections were tested. The literature has reported lots of web crippling tests, but there is few reports on web crippling behavior of aluminum composite sections. Interior-Ground (IG) and End-Ground (EG) loading conditions were adopted, with the specimens placed on the ground to simulate the load of floor joists. Specimens were also placed on a bearing plate with end (ETF) or interior (ITF) bearing load. The influence of supporting conditions, loading positions, bearing length and web slenderness ratios on web crippling ultimate bearing capacity and ductility of aluminum hollow sections was studied. The enhancements of infilling mortar were also evaluated. The results obtained from the experiments show that infilling the mortar in aluminum hollow tubes is an effective method for enhancing the ultimate capacity of the web, especially for specimens under Interior-Ground (IG) condition. Based on the results of parameter research, this paper proposes a series of design formulas for well predicting web crippling ultimate capacity of aluminum hollow and composite tubes under four different loading and boundary conditions.