Behavior of Boxed Cold-Formed Steel as Composite Beam with Rebar as Shear Connector
The use of composite systems comprising of concrete and conventional steel is commonly used in a multi-story steel frame with hot-rolled steel section. However, the use of cold-formed steel section designed as composite beam is yet to be established. Cold-formed steel (CFS) is usually categorized as a slender section which tends to buckle and deform. The strength of this section is usually reduced significantly as the section is very thin. However, all these problems can be significantly improved by designing the section as composite construction by integrating concrete and steel with the use of rebar as a shear connector. Therefore, this paper presents experimental works on the structural performance of cold-formed steel (CFS) section with self-compacting concrete (SCC) as a composite beam by means of the shear connection mechanism of the proposed using reinforcement bar. A specimen was carried out where the behavior of encased double cold-formed steel composite beam with composite slab was tested until failure. The proposed shear connector of size 12 mm was embedded in CFS and encased in SCC with a compressive strength of 40 N/mm2. The specimen comprised of two parallel CFS attached together to form encased beam with a concrete slab. Based on the experimental results it was found that the proposed composite system using bent-up rebar as shear connector showed slightly higher results than expected with ultimate moment capacity of 358.3 kNm for experimental and 341 kNm for predicted results. The failure mode was recorded as ductile which make it suitable to be used in the seismic zone.
KeywordsCold-formed steel Composite beam Encased sections Self-compacting concrete Shear connector
The work reported in this study was graciously supported by Universiti Teknologi Malaysia – Construction Research Center (UTM-CRC) and Institute for Smart Infrastructure and Innovative Construction (ISIIC) with Grant Number 4B235 under the supervision of Prof. Mahmood Md. Tahir and the help of Dr. Shek Poi. The author remains indebted for the support and help and collaboration to all members of the team.
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