. The action of materials under stress; . n each portion longest plate in such a case is sometimes required toextend in front of the pin four times the transverse distancefrom the pin centre to the line of rivets in the angle iron, sothat the stress may be transferred to the flange angles andplate, and not overtax the web. 223. Shear and Bearing.—The shear at any section ofthe pin is found from the given forces in the pieces resultant of the forces in the pieces on one side of anypin section will be the shear at that section. As the pin willprobably not fit the ho
. The action of materials under stress; . n each portion longest plate in such a case is sometimes required toextend in front of the pin four times the transverse distancefrom the pin centre to the line of rivets in the angle iron, sothat the stress may be transferred to the flange angles andplate, and not overtax the web. 223. Shear and Bearing.—The shear at any section ofthe pin is found from the given forces in the pieces resultant of the forces in the pieces on one side of anypin section will be the shear at that section. As the pin willprobably not fit the hole tightly (a difference of diameter ofone-fiftieth of an inch being usually permitted), the maximumunit shear will be four-thirds of the mean, § 86. Specifica-tions frequently give a reduced value for mean unit shear,which provides for this unequal distribution. Bearing area is also figured as if projected on the diame-ter with, e. g., 15,000 lbs. in place of 10,000lbs. per sq. inchon the semi-circumference. 2i4 STRUCTURAL 224. Bending Moments on Pins.—At a joint whereseveral pieces are assembled, the resisting moment, requiredto balance the maximum bending moment on the pin causedby the forces in those pieces, will generally determine thediameter of the pin. In computing the bending moments,the centre line of each piece or bearing is considered the pointof application of the force which it carries. This assumption is likely to give a result somewhat inexcess of the truth, as any yieldingtends to diminish the arm of eachforce. The process of finding the bend-ing moments will be made clear by anillustration. Fig. 84, A, shows theplan and elevation of the pieces on3 a pin, with the forces and directionsmarked. The thickness of the pieces,3 which are supposed to be in contact,is also shown. The joint must besymmetrically arranged, to avoid tor-sion, and simultaneous forces must be used, which reduce tozero for equilibrium. As the joint is symmetrical, the com-put
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectstrengt, bookyear1897
