262 STEEL REINFORCEMENT 



section and has notched shoulders for holding washers. 



FIG. 6 

 at a, may be inserted. 



FIG. 5 



The washers are punched so that they will slip over the 

 projections, and, then by turning, they are locked with the 

 bar. The trus-con bar is made in 

 I-, I-, 1, 11-. and l-in. sizes. 



Monolith Steel Bars. In Fig. 6 

 is shown the monolith steel bar. 

 This type of bar has no sharp cor- 

 ners, and is not reduced in area or 

 strength by deformations. It 

 also has large surface area. The 

 bar is grooved on the sides so 

 that round iron stirrups, as shown 

 These stirrups are held in place in 

 the bar by swedging the flanges of the bar together. The 

 monolith steel bars are made in sections equivalent to -, 

 f-, 1-, and 1^-in. square bars, and are 

 rolled for stirrups of &-, &-, f-, and -in. 

 diameter. 



Columbian Bar. A rolled shape known 

 as the Columbian bar is extensively used 

 in the construction of the Columbian fire- 

 proof floor systems and reinforced-con- 

 crete structures. The typical forms of 

 this type of bar are shown in Fig. 7. 

 Mild steel is used for rolling the Colum- 

 bian bar. This kind of steel has an ul- 

 timate strength of from 60,000 to 70,000 Ib. 

 per sq. in. and an elastic limit of one- 

 half the ultimate strength. The smallest 

 bar, shown in (a), is known as the 1-in. bar, while the type 

 of bar shown in (b), is made in 2-, 2^-, 3 j-, and 4J-in. sizes. 

 The 5-in. bar carries a double rib at the bottom. 



FIG. 7 



