Art. 135. DOUBLE-INTERSECTION WARREN TRUSS. 259 



second, and R 2 for the second, the same as RI for the first. The 

 sum of the reactions is equal to the total load. 



Fig. 189 (6). Shear in panels 4-5 and 3-4= ? ?=| up 



Shear in panels 2-3 and 1-2= * .r.s down 

 Shear in panel 0-1= f+ down. 



The same results will be obtained, of course, by starting at 

 the right hand end. The shear reverses at 3. In order to deter- 

 mine the character of the stress it is only necessary to consider 

 the direction of the shear in a panel, and the kind of distortion 

 it tends to produce in the diagonal. 



For similar members, the coefficients of truss c are the same 

 as of truss Z>. 



In Fig. 189 (6), chord 5-7 is in compression to resist J> 1 and 

 its coefficient is f At 5, the top chord 5-6 and both diagonals act 

 toward the right and, therefore, the coefficient for 3-5 is 



*+?+*= 



At 3, one diagonal acts toward the right and the other 

 (D 5 ) toward the left; the coefficient for 1-3 is \+f 4= V- At 

 1, both diagonals act toward the left; the coefficient for 0-1 is 

 Aj f f- =0 as is apparent at joint o. These coefficients may 

 be checked by starting at the right-hand end and proceeding in 

 a similar manner. It is somewhat easier to work from both ends, 

 up to the point where the shear changes. 



The coefficients for truss c may be taken off of truss &. Add- 

 ing the chord coefficients, the final chord coefficients are gotten 

 as shown in Fig. 189 (a), or they may be gotten directly on 

 Fig. 189 (a), from the diagonal coefficients. 



The live load coefficients for the diagonals are independent 

 for each truss, but are the same in the two trusses for members 

 with the same subscript. For the end panels (D v D. 2 , and D 7 ) 

 the full load coefficients are the maximum also. For the other 

 panels the diagonal coefficients are easily found if the proper 

 partial load is considered, and are given at the lower ends of D 3 

 to D 6 in Fig. 189 (6). 



Having all the coefficients it is a simple matter to calculate 

 the stresses (13 1). 1 



l lt is possible to have a multiple-intersection truss that is statically 

 determinate. Some of these are, however, collapsible or unstable. A 

 discussion of such trusses may be found in a paper by Mr. G. N. Linday, 

 in the Journal of the Western Society of Engineers, Vol. VIII, p. 272; also 

 in Mueller-Breslan's Graphische Statik, Vol. I. 



