198 APPLIED MECHANICS 7 
Exercises XII. | 
1-8. Draw the stress diagrams for the structures shown in Fig. 269. Measure 
the results, and either tabulate them or mark them on the frame diagram. Indi- 
- “ 
Ex.) c B Ex. 2. pokey | 
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y a J J J A 
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= = c 
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A J J J J J J h- P $s Vv Hr 
B a Ex.5.| ¢ Yr,| 0 | Ww 
ac} x.5.4 EY 41—\p KN J ’ 
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| B Alf | 
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Fo EB eee AK K 9 aKa ie 
Ex.6. Ex.7. 
Fie. 269. 
cate on the frame diagram the members which are in compression by lining them 
in with thick lines. In addition to determining the results graphically, they 
should also be found by calculation. : 
1. Span=2t feet. The loads are as follows: AB=EF= 250 Ibs., 
BC=CD=DE=500 lbs, 
2. Span=30 feet. The dead loads are as follows: AB=GH=400 lbs., 
BC=CD=DE=EF=FG=800 lbs. The wind pressure is to be taken at 6000 Ibs., 
acting at right angles to, and distributed over, the sloping surface as follows: 
2000 lbs. at-each of the intermediate joints, and 1000 lbs. at the top and bottom 
joints. The reactions at the supports due to the wind pressure are to be assumed 
to be parallel. Tabulate the stresses due to (1) dead load, (2) wind on left, 
(3) wind on right, and state also the maximum stress in each bar. . 
3. Span=48 feet. The loads are as follows: AB=GH=500 lbs., each of the 
other loads =1000 Ibs. . 
4. A wall crane. The bar BC is horizontal, and 10 feet long. The bar BD 
bisects the angle ABC, and is 3 feet 9 inches long. The distance AB is 8 
feet. The chain passes over a pulley at C, as shown, and supports a weight W of 
1000 Ibs. ; 
5. Pent roof truss projecting 18 feet from the wall. Each load shown is 1000 Ibs, 
6. Warren girder of 40 feet span. Case (a). There is a load of 10 tons at the 
joint EJKLD. Case (5). There is a load of 8 tons at the joint EJKLD, anda 
load of 6 tons at the joint CNOPB, Case (c). There is a load of 6 tons at each 
of the joints in the bottom boom, 3 
7. Span, 48 feet. Load AB=load GH=8 tons. Each of the other loads 
shown =6 tons. : 
8. Curb roof truss of 48 feet span. The loads AB and JK are each 500 lbs., — 
and each of the other loads shown is 1000 lbs. Case (a). Take the truss as 
shown. Case (5). Suppose the bar LS to be removed, and that the truss is 
converted into a three-hinged arch, as explained in Art. 182. Determine the 
reactions at the hinges, and the stresses in the various members. ; 
9. A jointed frame, shown in Fig. 270, is subjected to six forces, acting one 
at each joint. The directions of the forces bisect the angles marked, and the 
magnitudes of three of them are given inthesketch. Find, graphically or other- 
