CORRUGATED BAR COMPANY, INC. 



Axial Compression. For concentric compression on a plain concrete pier, 

 the length of which does not exceed four diameters, or on a column reinforced with 

 longitudinal bars only, the length of which does not exceed 12 diameters, 22.5 per 

 cent of the compressive strength may be allowed. 



For other forms of columns the stresses obtained from the ratios given in the pre- 

 ceding section on "Design" may govern. 



Compression in Extreme Fiber. The extreme fiber stress of a beam, calculated 

 on the assumption of a constant modulus of elasticity for concrete under working 

 stresses may be allowed to reach 32.5 per cent of the compressive strength. Adjacent 

 to the support of continuous beams stresses 15 per cent higher may be used. 



Sheer and Diag^onal Tension. In calculations on beams in which the maximum 

 shearing stress in a section is used as the means of measuring the resistance to diagonal 

 tension stress, the following allowable values for the maximum vertical shearing stress 

 in concrete, calculated by the method given in Formula 22 (see page 8) are recom- 

 mended : 



(a) — For beams with horizontal bars only and without web reinforcement, 2 per 

 cent of the compressive strength. 



(b) — For beams with web reinforcement consisting of vertical stirrups looped about 

 the longitudinal reinforcing bars in the tension side of the beam and spaced hori- 

 zontally not more than one-half the depth of the beam; or for beams in which longi- 

 tudinal bars are bent up at an angle of not more than 45 degrees or less than 20 degrees 

 with the axis of the beam, and the points of bending are spaced horizontally not more 

 than three-quarters of the depth of the beam apart, not to exceed 43^ per cent of the 

 compressive strength. 



(c) — For a combination of bent bars and vertical stirrups looped about the rein- 

 forcing bars in the tension side of the beam and spaced horizontally not more than 

 one-half of the depth of the beam, 5 per cent of the compressive strength. 



(<3?) — For beams with web reinforcement (either vertical or inclined) securely at- 

 tached to the longitudinal bars in the tension side of the beam in such a way as to 

 prevent slipping of bar past the stirrup, and spaced horizontally not more than one- 

 half of the depth of the beam in case of vertical stirrups and not more than three- 

 fourths of the depth of the beam in the case of inclined members, either with longi- 

 tudinal bars bent up or not, 6 per cent of the compressive strength. 



The web reinforcement in case any is used should be proportioned by using two- 

 thirds of the external vertical shear in Formula 24 or 25 (see page 9). The effect of 

 longitudinal bars bent up at an angle of from 20 to 45 degrees with the axis of the 

 beam may be taken at sections of the beam in which the bent up bars contribute to 

 diagonal tension resistance (see "Diagonal Tension and Shear," page 198) as reducing 

 the shearing stresses to be otherwise provided for. The amount of reduction of the 

 shearing stress by means of bent up bars will depend upon their capacity, but in no 

 case should be taken as greater than 4)^ per cent of the compressive strength of 

 the concrete over the effective cross-section of the beam (Formula 22). The limit of 

 tensile stress in the bent up portion of the bar calculated by Formula 25, using in this 

 formula an amount of total shear corresponding to the reduction in shearing stress 

 assumed for the bent up bars, may be taken as specified for the working stress of 

 steel, but in the calculations the stress in the bar due to its part as longitudinal 



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