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220 TAE MarRINE. REVIEW BEAM KNEES AND BRACKETS RECOMMENDED --~ Fie.! 10"BEAM KNEE. WITH 10-2°RIVETS -- IO WITH 9-4 RIVETS Fig. 3 , g" BEAM KNEE 9" BEAM KNEE 4 : 1 WITH 8-z% RIVETS we ---- 5p ee ae oF 0 | = thes 3 He? ce oi as™ g S x N ' } f Fis.5 | 28 Fic. 6 _ fie. 4 | 7" BRACKET { 6"BEAM KNEE 7" BEAM KNEE WITH 5-2"RIVETS | WITH 6~2°RIVETS WITH 7-2° RIVETS WITH 4-2°RIVETS knee in such a way that the ratio of the resisting moments of the rivets to the resisting moment of the beam shall be kept between more narrow limits. It is recommended that these limits be made 1.20 and .1.60 for shearing, and 1.30 and 1.80 for crushing the metal in front of the rivets in the knees of all beams deeper than: 5 in. For beams 5 in. in depth and less, it is recommended that sufficient rivets be used to close the joint efficiently without fixing the maximum value of the above ratios. The Table IL on Plate 3, and the sketches on Plate 4 have been pre- pared in accordance with the above recommendations. The desired ratios of resisting moments have been ob- tained by varying the depth of the knees or the number of rivets. In WITH 4-#°RIVETS Sas ahs 14" 3] ° v3 | eS an > " c #/ eh ise Fis. 7 Fig. 8 bis fie 8 6" BRACKET 6" BRACKET 5 BRACKET WITH 5 ~2"RuveTS WITH 5-2 RIVETS WITH 5-3°RIVETS + | --> 10" x i © Ss t see . a Fis. 10 9 Fic. (I Fig. 12 4$" BRACKET 4" BRACKET 33 BRACKET WITH 4-2° RIVETS this table, 34-in. rivets have been used any for all beam knees; but; had ® ie ® Ee \® ~ Sneen Sreovel| \@ Frame CH. July, 1909 beam been of a thickness outside of the limits requiring 34-in. rivets, it would have been necessary to use rivets of appropriate diameter for that thickness, and modify the number of rivets in order to keep the ratios of the resisting moments of the riveting to the resisting moment of the beam within the prescribed limits, These results hold good for both knees and brackets used on _ either beams or stiffeners. : In the case of brackets the rivets should be so disposed that the brackets will be equally strong along both riveted sides. The comparison between the resist- ances of a beam subjected to bending and the shearing of the rivets in its knees by twisting was originally done under the direction of Professor W. Hovgaard for use in the instruction of the assistant naval constructors at the Massachusetts Institute of Tech- nology. The results of this comparison convinced the author that they would be of interest to this society. He therefore investigated the resistance of the metal to crushing in front of the rivets. The tables therefore show a comparison between the resistance of the beam. and the resistance of the riveting in the beam knees to shear- ing and crushing of the metal in front of the rivets, when the whole beam is subject to bending. Written Discussion by Robert Curr. Robert Curr.--It will probably be of interest to add the methods practiced on the great lakes to Mr. Hunt's valuable and interesting paper. Fig. 1 shows a beam connection. The frame and beam are 12 in. chan- néeland the bracket is 15 lb. per sq. ft., flanged 3 in. deep on edge. There are 12 rivets 34 in. diameter, and are equal to the area of section of the beam or frame. The rivets cam CH-- ww te ae a 7