hi UN I. -1.0 AD STRESSES 



not given, but the value is Jl . Two-thirds of tln> com- 

 pression, or 14*, Nvill \>c ron-idei-ed HYeetive in counirrlial- 

 ancing the live-load tension in JK. Tin live load must be 

 advanced beyond the position of maximum live-load ten- 

 sion in JK (i.e., to* at panel point 5) until S t , or the stress 

 in JK, equals 14*. This must be done by trial, S being 

 figured each time by formula (25). It is found that \\lu-u 

 111' of loading has advanced upon the bridge, tin- condi- 

 tion is approximately -atMied. For this position of loading 



3/4 22201 



M e = M*--M = (2565 - 175) == 2390 



46.04 



Therefore, 



& = .00580(22201) - .0466(2390) = 10*. 

 This value of & = 10* balances % D = -- 14*, nearly 

 enough for practical purposes. Therefore, compute T for 



this position of the live load. 



K - 1x55 



M = fg (22261) -- 2f>r,:, 1 1340 

 T = .00203(11340) = 23* 



300 

 Impact factor = jr = .725 



Impact stress for T = .725 X 23 = 17*. 



PROBLEM 2. 

 Live-load Stresses in a Pn\i\ 7V?/.v* ?///// 7V//v//// / 



The complete data for this problem are given in Fig, 

 14. Formulas (21), (29), and (30) give the values of the 



