Cyclopedia of architecture, carpentry, and building : a general reference work . Fig. 21 a). Then the two letters onopposite sides of any line serve to denotethat line and the same large letters areused to denote the force acting in thatline. Thus cd (Fig. 21a) refers to themember 12 and CD should be used tostand for the force or stress in thatmember. 25. Polygon for a Joint. In draw-ing the polygon for all the forces at ajoint, it is advantageous to represent theforces in the order in w^hich they occurabout the joint. Evidently there arealways two possible orders thus (see Fig. 20 d) F^,, GOO
Cyclopedia of architecture, carpentry, and building : a general reference work . Fig. 21 a). Then the two letters onopposite sides of any line serve to denotethat line and the same large letters areused to denote the force acting in thatline. Thus cd (Fig. 21a) refers to themember 12 and CD should be used tostand for the force or stress in thatmember. 25. Polygon for a Joint. In draw-ing the polygon for all the forces at ajoint, it is advantageous to represent theforces in the order in w^hich they occurabout the joint. Evidently there arealways two possible orders thus (see Fig. 20 d) F^,, GOO, 1,875, and1,800 is one order around, and F^, 1,800, 1,875, and GOO is first is called a clockwise order and the second 6ooolbs. Fig. 21. 167 34 STATICS A force polygon for the forces at a joint in which the forces arerepresented in either order in which they occur about the Joint iscalled a polygon for the joint, and it will be called a clockwise orcounter-clockwise polygon according as the order followed is clock-wise or counter-clockwise. Thus in Fig. 17 (b), ABCDA is aclockwise polygon for joint (1). ABCDA is a polygon for the ; ISoollos. (a.) b / \<= / / ^ d y (4) \ t f ^ 6oolbs. c i .(2) forces at the joint; it is not a poly-gon for the joint because the orderin which the forces are representedin that polygon is not the same aseither order in which they occurabout the joint. (Draw the counter-clockwisepolygon for the joint and compareit with ABCDA and ABCDA.) 26. Stress Diagrams. If thepolygons for all the joints of a trussare drawn separately as in Example1, Art. 23, the stfess in each mem-ber will have been represented twice. It is possible to combinethe polygons so that it will
Size: 1314px × 1901px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1900, booksubjectarchitecture, booksubjectbuilding
