GRAPHIC STATICS 



217 



for the web members as shown by the dotted lines at (6), taking 

 the joints in numerical order. 



It is evident that the panel loads to the right of load EF do 

 not affect the web members to the left of this load ; therefore, 

 having determined the web forces, complete the load line 07, 

 and reactions jk and ka, at (6), to obtain the forces in the chord 

 members. The diagram Imnopqr should be made identical with 



Fig. 132. The Wrigley Solution of the Fink Truss Problem. 



the dotted diagram I'm'n'o'p'q'r'. The above method applies as 

 well to diagrams for wind loads. 



In Fig. 133 three methods are shown for drawing the reciprocal 

 diagram for a Fink truss. The Barr method is to proceed with 

 the construction until the line is drawn from v to u. Then on the 

 truss draw a dotted line from joint 4 to joint 6. On the reciprocal 

 diagram from the point u draw a line towards t, of indefinite length. 

 Transfer from the truss diagram the line from 4 to 6, meeting, 

 on the reciprocal diagram, the line ut at '/'. and terminating at 

 r, on the line er. From r draw the line rs and the remainder of 

 the diagram is then readily drawn. This is applicable for cases 

 of unequal loading and for wind. 



A method which is correct when the reactions are equal and 

 the joints are equally loaded, is to draw the line, on the reciprocal 



