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230 APPLIED MECHANICS 
plate. Design also the cover plate for one of the,boom joints, and show the 
general arrangement of stiffeners. Scale for section, | inch to 1 foot, Horizontal - 
scale for booms, | inch to 5 feet. [U.L.] 
2. A built-up steel plate girder has the following cross sectional dimensions: 
—tThe flanges consist of three plates, each 4 inch thick and 16 inches wide; 
the web consists of one plate, 45 inches deep and @ inch thick; the web and 
the flanges are connected together by angles 4 inches by 4 inches by $inch. If 
the external shear force at a particular vertical section of this girder is 112 tons, 
determine (a) The intensity of the shear stress in the horizontal plane of the 
section in which the web plate meets the flange plates. (b) The proper pitch to 
adopt for the 1} inch rivets used to connect together the web and the flanges, if 
the intensity of the shear stress in them is not to exceed 4 tons per square 
inch. [U.L.] 
8. Draw the M/I diagram for the plate girder in the worked example (Art. 204). 
Find graphically from this the actual deflection curve of the girder. Measure 
the maximum deflection. Show by how much the deflection curve differs from 
an arc of a circle. oie 
4. Plot the shear distribution curve for an end cross section of the plai 
girder in the worked example (Art. 204). What is the ratio of the mean to 
—— shear stress? Compare each with the shear per inch of depth 
assumed. ; 
5. Design the grouped joint for three } inch steel plates 16 inches wide. 
Diameter of rivets, { inch. Holes punched and reamered. A single outside 
cover to be employed. The holes in the flanges to be staggered. Calculate — 
the various efficiencies of the joint. What saving of metal is there over three — 
separate joints ? 
6. A rolled steel joist is continuous over three spans. One extreme end is — 
built firmly into an abutment, while the other may be taken as freely ny He 
The load carried is 1 ton per foot-run. The two outer spans are each 10 feet, — 
and the centre span is 12 feet. What are the loads on the piers? Draw the ~ 
bending moment and shearing force diagrams. Design the beam. 4 
7. Design a plate web girder of the fish-bellied type suitable for an overhead 
traveller of 50 feet span. There are two such girders upon which the trae 
carriage runs. The maximum weight to be lifted is 40 tons, and the weight 
the traverser may be taken as 4 tons. 
8. A three-girder bridge, to carry a double line of rails, has a clear of 
36 feet, and the girders have a length of bearing at each end of 2 feet 6 inches. 
The girders are to be of the plate web type. The flooring is to be trough form, — 
weighing about 7 cwt. per foot-run of the whole width of the bridge. The 
permanent way, including rails, sleepers, etc., may be taken as equal to 160 
pounds per foot-run for each line of rails. Estimate in any way you please the 
approximate weight of the main girders, and determine the maximum bending 
moments and shear on each of the side girders and on the central girder for the 
above dead loads, and for a live load of 40 cwt. per foot-run per single line of 
rails. Choose your own working stresses, and design a suitable cross section — 
for the centres and ends of the central girder and for one of the side girders. 
Determine the necessary pitch of rivets in both cases. _ [U-L.] 
9. Design for a double track railway bridge. Span between bearings, 60 
feet. There are to be two main girders, spaced 26 feet apart, centre to centre. 
The deck of the bridge is carried by cross girders placed’ at about 7 feet to 8 
feet pitch, and consists of trough flooring running longitudinally. The sleepers 
are laid transversely. The dead weight of the floor may be taken as 1} cwt. 
per square foot, and the equivalent uniform live load at 2 tons per foot-run for — 
each line of way. The maximum load on one axle may be assumed as 20 tons. 
