LIVE-LOAD STRESSES 



mr - - .1094(30) +.309(103) +.0027(302) = + .7 

 -.1094(50) + .309(103) +.0027(302) = - .7 



Therefore w* at (7i gives a maximum tension in 

 and its value is 



S = SCAT = -.1094(230)+.309(1846)+.0027(19001)=83*. 



ICr 



By use of the formula -7- = sCWand Rule 2 of Ait.:; 



the position of loading for maximum eompn im in UJ^ 

 is now determined. Try wheel J at r ; , with the loading 

 advancing toward the right. Note that the signs of the 

 coefficients remain unchanged. Tak< tin values of the load 

 sums and moment sums for J40 from Table 2. 



^ = Z.CW = -.0105(192) + .0863(10) = - 1.3 

 2L = zCW = -.0105(192) + .0863(30) = + 0.6 



Therefore w t at U* gives a maximum negative stress, or 

 compression, in /L 4 , and its value is 



S = 2CM = -.0105(7092) + .0863(80) = - 67*. 



The above values of 83* and 67* for maximum tension 

 and compression in U^L 4 may be checked by use of formula 

 S = qA g (2), the values of q being taken from Table 16. 



Tension UJL* by Equivalent Uniform Load. 

 The area of the tension part of the influence line equals 

 A z = 27.2 



The influence line ohkm is not triangular, but a tri- 

 angular influence line with intervals h = 10 ft. and h = 

 45 ft. approximates its shape closely enough for the selec- 

 tion of an equivalent uniform load. For li = 10' and k = 

 fable 16 gives 3.080* as the equivalent uniform load. 



