256 



STEEL REINFORCEMENT 



Square-Twisted Bars. The square-twisted bar consists of 

 a square bar that is twisted by giving it a certain number of 

 turns around its axis, either while it is hot or while it is 

 cold. This bar is often known as the Ransome bar. 



By twisting the bar to the screw shape, as shown in 

 Fig. 2 (a), a form is obtained that has great resistance to 

 pulling from a mass of concrete. 



If the square bars are twisted cold, their elastic limit and 

 ultimate strength are increased from 8 to 25%. 



PHYSICAL PROPERTIES OF THE RANSOME BAR 



11 



$ 



3*3 



.0625 



.1406 



.2500 



.3906 



.5625 



.7656 



1.0000 



1 . 5625 



.213 



.478 



.850 



1.328 



1.913 



2.603 



3.400 



5.312 







62,350 

 61,800 

 60,120 

 57,890 

 56,720 

 56,150 

 55,760 

 55,450 



6 5 



' 03 



5 1 



86,700 

 86,600 

 86,850 

 85,820 

 85,240 

 84,730 

 84,275 

 83,150 



.0 JH O 

 1^ 



s 



3,897 

 8,689 

 15,030 

 22,612 

 31,905 

 42,988 

 55,760 

 86,641 



IS | 



3*8 



S5(2 



5,419 

 12,176 

 21,713 

 33,520 

 47,948 

 64,869 

 84,275 

 129,921 



The physical properties of the Ransome bar are given in 

 the accompanying table. 



Spiral Bar. In Fig. 2 (&) is shown a type of twisted bar 

 called the spiral bar. It is made by rolling steel and then 

 twisting it. The twisted bars have elastic limits of from 

 65,000 to 80,000 Ib. The section of the bar is practically 

 round, with four attached half-round beads. These beads 

 assume the spiral form on twisting the bar, and the same 

 advantage with regard to the bond is secured as with square- 



