DEFORMATION DIAGRAM 



'35 



u 



u; 



(e) 



(b) 



DeformaTion Diagram /^- < C^\ / / - -- "--,. x ^ 



Simple Truss x u#3 ?&< LO&-'- "-^Lo 



\ V .,' / i* 0.574 inches w 



Verlical Loads V^^Jo ' 



FIG. 72. 



determine the new position of joint L relative to the other points. In 

 like manner perpendiculars erected at the ends of deformations 6 and 

 7 determine U lf and finally perpendiculars erected at. the ends of 

 deformations 8 and 9 determine L . The deformation diagram for the 

 right half of the truss is constructed in the same manner. The horizon- 

 tal line joining L and L 1 represents to scale the movement of the 

 joint Z/ . 



In drawing the deformation diagram it is immaterial whether plus 

 deformations are laid off toward the joints and minus deformations 

 away from the joints as was done in the preceding problem, or the 

 reverse. The former method is more common, but the latter is prob- 

 ably more consistent. The deformation diagram (b) if drawn in the 

 latter way would be turned upside down and inside out. 



Calculation of Dead Load Stresses in Arch. In Fig. 71, (b) 

 is the stress diagram for the arch as a simple truss with vertical loads 

 as shown in (a) ; and (d) is the stress diagram for the arch as a simple 



