594 THE DESIGN OF STEEL DETAILS. CHAP. XVII. 



The total bearing area required on one side of the member is, 



A = 347,850 = in 



24,000 



The total thickness of bearing required on one side, using a 6% in. pin, is, 



14.49 



/ = -7 = 2.32 in. 

 6.25 



This thickness will be provided by the plates A, B, C, D and E as shown in Fig. 14. The 

 plate B in the web and has a thickness of % in. Plate C must act as a fill plate so must be of the 

 same thickness as the bottom angles or ^ in. The outside plate E and the inside plate A should 

 be thinner than D so they will be made % in., and D will be made J^> in. The actual thickness of 

 bearing is then 2.375 in., an d the required thickness is 2.32 in. In arranging the plates a clear- 

 ance of y% in. should be allowed between the plates which pass around the pin, and the nearest 

 plate as shown in Fig. 14. It is necessary to put a 3/16 in. fill plate, F, opposite the top angle 

 to make up for the difference in thickness in the % in. bottom angle and the 7/16 in. top angle. 



The stress transmitted to a plate by the pin is equal to the ratio of its thickness to the total 

 thickness, multiplied by the total stress. The stresses in the various plates are as follows. 



Stress in A = ~~ X 347. 850 = 54.92O lb. 



B = x 347>8s = 73 ' 24 lb - 



*5/D 



C = 2^375 X 347 ' 85 = 9Il53 lb ' 



X 347,850 = 73,240 lb. 



E = rf^ x 347,850 = 54.920 ib. 



2-375 



Total = 347,850 lb. 



An exact solution for the number and location of rivets is not practicable. A common solu- 

 tion is to consider that all the pin plates transmit their stress to the web and that the web, in turn, 

 distributes this stress over the section. This solution overstresses the web in the vicinity of the pin. 



A better solution is to consider that the stress in the cover plate and top angles is transmitted 

 in double shear or bearing on the vertical leg of the top angles from the web plates and pin plates 

 through the rivets in the vertical leg of the angles. The stress in the bottom angles is transmitted 

 in double shear or bearing on the vertical leg of the bottom angles from the web plates and pin 

 plates through the rivets in the vertical leg of the angles. The stress on the rivets between the 

 web plate and plate C is equal to the sum of the stresses in C, D and E, minus one-half the sum of 

 the stresses in the cover plate, top angles and bottom angles on one side. 



The number of rivets in the plate A is determined by the stress in A only, and is controlled 

 by single shear and is, 



L.M^.srrveto, 



7,220 



The number of rivets in the plate E is determined by the stress in E only, and is controlled 

 by single shear and is, 



7,220 



The number of rivets between D and the top angle and between B and the top angle is de- 

 termined by bearing on the 7/16 in. angle and is, 



90,500 + 44,450 



= v ' 3 ^^- = 15 rivets. 



9,190 



The number of rivets between D and the bottom angle and between B and the bottom angle is, 



