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Swimmer bars are a new type of shear reinforcement. They are short inclined steel bars welded to both top and bottom flexural reinforcement. Punching shear takes the form of a truncated pyramid or a truncated cone. A counteract truncated pyramid or a truncated cone of reinforcement formed by swimmer bars will be employed to generate four inclined planes (in the case of truncated pyramid) crossing the four inclined planes of the cracks and a conical surface (for the case of truncated conical shape of failure). The results obtained from plates provided with these plane-crack interceptors, proved the effectiveness of this new system. The number of truncated pyramid-crack interceptors may be increased for heavy punching shear forces. The provision of these swimmer bars has the potential to eliminate the need of drop panels in flat slabs and raft foundation in the vicinity of columns, leading to savings and ease of construction. The results of this study are particularly useful to the design and construction engineering professionals.

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Dr. Moayyad Al-Nasra, PhD, P.E. is the chair of the Engineering Technology Department at West Virginia University Institute of Technology. Dr. Al-Nasra has over 26 years of teaching, research and engineering practice experience. He has several publications in the area of civil engineering.

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