BEAMS AND STRUCTURES 



75 



Calculate B in Eq. (2) above, with C = 1. 



Use this value of B to calculate <r in Eq. (1), from which a = 22,700 lb. per sq. in. 



From Eq. (3), 



K = 12 



/50; 

 \22, 



000\ 

 700/ 



y2 



= 17.8 



From Eq. (4), 



J = 22,700 tanh (17.8 X 0.051) 



= 22,700 X 0.72 = 16,200 lb. per sq. in. 



ANGLES IN COMPRESSION 



For angles, the following table gives the value of a for different values of L/p : 



For allowable stresses for angles, 



where t = thickness of angle 



K 



P /tY 



b ?= width of leg 

 149.1 +0.lf- - 47 j 



This equation holds only for C = 1 . 



SHEAR MEMBERS 



Shear-resisting web designed to avoid buckling 



Ktt'D 



fs = 



where fs = critical shear stress or buckling stress 



t = thickness of plate 



b = depth of the panel or the distance 



between stiffeners, whichever may 



be the lesser 



K = coefficient depending on value of the 



ratio b/a as given by the curve. Fig. 4 



bH 



(5) 



D = flexural stiffness factor 



0-i) 



12 



E = 10,500,000 lb. per sq. in. for 24 ST 



- = Poisson's ratio = 0.25 for 24 ST 



m 



Note: The accompanying Fig. 4 gives values of K, and Fig. 5 indicates tlie dimension a and b. If in a design 

 problem 6 is greater than a, the terms should be transposed. In the equation below, b is always the smaller of the two 

 dimensions. 



Substituting in Eq. (1), 



L = 



9,240,000X 



{b/ty 



(6) 



