Economy of Material in Frame-structures. D95 
The minimum frame is composed of the two quadrantal 
bars DF and EG, having their common centre at OC, of all 
the radii of these quadrants, and their four tangents AD, 
AE, BF, and BG. The orthogonal system is completed and 
extended to infinity as indicated by the dotted lines. 
The quadrants above C and all straight lines extending 
obliquely downwards and outwards from the line of action of 
are compressed, all the other lines extended. 
The necessary volume of material is 
1 NG on) (6 aeaaaen E 
Fa(3 +3)(p + Q) 
where a=AC=CB. 
2a. (Fig. 3.) With the same applied forces the condition 
may be imposed that the frame shall lie wholly on one side 
of the line AB. 
The form of the minimum frame is then as in fig. 3, and 
consists of the semicircle on AB and its radii. The figure to 
be subjected to the test deformation consists of the semi- 
infinite plane below AB, all the radii from C being extended 
and the semicircles about C compressed. 
