THE DISTRIBUTION OF SHEAR STRESS 811 



F B 



a(r-**) 



and this relation will only hold for values of y between - and 0. 



m 



and when y = 0, g = x - (D 2 - d 2 ) + -^- 





It should be noticed that, in passing from the flange to the 



F 



web, the shear stress increases suddenly from -y (D 2 d 2 ) to 



81 



FB 



-=7(D 2 rf 2 ), and a consideration of the shear stress diagram 



for this section will show that the web practically takes all the 

 shear. 



Example 2. To investigate the distribution of shear stress 

 over a square section in which the diagonal is horizontal. 



FIG. no. 



Let 2d be the length of the diagonal, and let q be the shear 

 stress at AB, at distance y from the diagonal. 



Then AB = 2(d - y) 



Area of the triangle ABC = (d - t/) 2 



