186 TEST OF A OAST-lllON BEAM. 



Putting in all these values 



700 x (3G) 3 



48 X 0-0650 x 0-69 

 = 15,160,000 Ib. per sq. in. 

 = 6,750 tons per sq. in. 



By again making use of the diagram on Fig. 89, p. 181,. 

 the equivalent load on a 2 in. x 1 in. section can be 

 found. 



W 



Equivalent breaking load = ^-^ 



1'Uo 



_ 3,000 

 1-03 



= 2,910 Ib. 



It has been shown that the maximum stress in bending, 



f _M 



fb - ~z. 



M being the bending moment at the section in question, 

 and Z being the " modulus of the section," which in this 

 case is 



b d - 



7 = 



6 



For a beam loaded centrally and supported at the ends, 

 the maximum bending moment 



M 



M = 



4 ' 



the symbols having the same meaning as before, so that 

 f Wl 6 

 4 ' b.d 1 



Now, in the present instance, 



W = 3,000 Ib. 

 I = 36 in. 

 b = 1-03 in. 

 d = 2-00 in. 



Putting these values in the above expression, 

 , = 3,000 . 36 . 6 

 4 1-03 . 4 

 = 694,000 Ib. per sq. in. 

 or = 17'6 tons per sq. in. 



