STEEL REINFORCEMENT 



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twisted bars. An added advantage is assumed to exist in 

 the elimination of all the sharp corners that occur in the 

 square bar. 



Kahn Cup Bar. One of the latest types of reinforcing bars 

 to be commercially used is the Kahn cup bar illustrated in 

 Fig. 2 (c). The ribs are connected by cross-ribs, forming 

 cups, or depressions, of such a shape as to allow the concrete 

 to flow into them readily. In this way, a positive mechanical 

 bond in the concrete is provided. The properties of the 

 Kahn cup bar are given in the accompanying table. 



PROPERTIES OF THE KAHN CUP BAR 



Square-Twisted Lug Bars. The twisted lug bar shown in 

 Fig. 2 (d) is a development of the square-twisted bar. The 

 square bar in this case is rolled with rounded corners, and 

 with projections, or lugs, a at intervals, thus providing 

 additional mechanical bond in the concrete. The rounded 

 corners of this bar eliminate the sharp angles of the ordinary 

 square-twisted bar. These bars have a high elastic limit. 

 Their safe working strength is based on a safe unit stress 

 of 20,000 Ib. The properties of twisted lug bars are given 

 in the accompanying table. 



Corrugated Bar. In Fig. 2 (e) and (f) are shown two styles 

 of deformed bar of the corrugated type known as the Johnson 



