Experimental study on shear performance of composite beam using lipped channels

Abstract

This study presents an experimental investigation of a composite beam with a U-shaped steel section and concrete, produced using a new cold-forming method. The shear strength of the composite beams was evaluated with lipped channels of two different thicknesses (2.3 mm and 3.2 mm) and three different shear span-to-depth ratios (1.5, 2.0, and 2.5). The experiments were conducted with the aim of enhancing the flexural and shear performance by installing trapezoid side plates on the lower side of the beams. A total of six specimens were fabricated and subjected to shear testing using a three-point loading method. The results showed that all specimens exhibited typical shear failure, with a tendency for the experimental shear strength to decrease as the shear span-to-depth ratio increased, with a maximum reduction of 15 %. Conversely, when the shear span-to-depth ratio remained constant, an increase in the thickness of the lipped channels from 2.3 mm to 3.2 mm resulted in an average increase in shear strength of 8 %. Additionally, the applicability of the design formulas prescribed in the building steel structure design codes was reviewed to evaluate the shear performance of composite beams using lipped channels. The ratio of experimental shear strength to design shear strength, considering the steel section with lipped channels and trapezoid side plates, ranged from 1.48 to 1.94 (average 1.68), indicating relatively accurate predictions of design shear strength. However, the ratio of experimental shear strength to design shear strength, considering only the reinforced concrete section, averaged 9.93, which underestimated the shear strength.