Experimental investigation on local stability enhancement of steel tubular profile introducing hybrid metal-polymer sections

During a year tubular sections successfully gained a leading positions in various structural applications. This type of the profile is approved by the architects and structural engineers. The first favor the aesthetics and integrity the shapes can provide, the second are attracted by the ease of manufacture, lightweight and structural features such as high resistance to torsional effects. Despite the years of design practice and application the strengthening under concentrated loads still raises structural challenges and highly increases the weight of the tubular sections. This study provides a new approach to increase the bearing capacity of the hollow sections under concentrated load by means of forming a hybrid metal-polymer section. The experimental program embeds slender rectangular steel hollow sections with adhesively bonded lightweight polymer infills. The additive manufacturing is utilized to create low density polymer stiffeners which increase the weight of the section only 28%. The tailored topology of the stiffeners prevents deformations of the flange whereas composite effect enhance resistance of the web to premature buckling. The polymer infill by itself increases the bearing capacity of the steel profile 35%, adhesive engagement enhance it to 85%. Local deformations caused the failure of the reference specimens without reinforcement. On the contrary, the failure of the hybrid metalpolymer ection grounds the possibility to increase the bearing capacity and deformation energy absorption of the slender sections by preventing premature buckling of the web as well as reinforcing the flange and ensuring efficient use of materials.

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