U\ l.-l.n \l> -II 



c-^ -" 



Counter-trn-ion in vertical post; usual case. 



Formulas (21), (2,V. and (24) are of the general fnrm 



S = GM< - HM> (27) 



where the coefficients (; and // may he tabulated thus: 



TI/JK f tut ////>< / H 



i/i 1 



Horizontal chord ... 



nr V 



Vertical pn-t TT 



Inclined wel. member. . .-rj- /; 



The rate of variation of S in formula (27) is 



= GW< - HW 3 = H(^W 4 - TF,) . . (28) 

 When S in formulas (21), (23), or (24) is a maximum 

 \JrWt IT j pa>-e< through zero. 



Through Pratt Truss Parallel Chords. 

 Stress in hanger, use formulas (14a) and (15a) 



Stress in horizontal chord = S, = (}M< - C-) M 21 



\ // y/ \ j}/ 



"vertical post = ,S f , - (M-W, (^)lf, 



x I j 1 \j// 



t, = -S, f3(D 



