GRAPHIC STATICS 



221 



joint in order. Reciprocal diagrams show plainly when there is 

 a redundancy of members and also show when a member should 



Fig. 138. Howe Through Truss. 



be added. The student is advised to make reciprocal diagrams 

 for odd panel trusses of the Warren, Howe and Pratt types after 

 studying this chapter, as an exercise. Odd panel trusses have 

 been purposely omitted in order to give the student an oppor- 



o.n 



M 



Fig. 139. Howe Deck Truss. 



tunity to exercise his brain in studying the problem. It will 

 help to make the complete diagram and run the lines from the 

 two ends, so if there is any trouble encountered it will be caught 

 in the middle and can be readily solved. In some trusses there 



\T\ 



Fig. 140. Pratt Through Truaa. 



may be members that are not stressed except under moving 

 loads. Determine this positively. Take nothing for granted. 



