586 



THE DESIGN OF STEEL DETAILS. 



CHAP. XVII. 



between I and 2, and is 165,400 Ib. The maximum shearing unit stress is 165,400 -5- 28.27 = 

 5,850 Ib. per sq. in. The allowable shearing stress was 9,000 Ib. per sq. in. 



Bearing. The bearing stress in L$U\ is 160,650 -5- (6 X 1.94) = 13,800 Ib. Bearing stress 

 in UiUz is 165,400 -j- (6 X 1.88) = 14,600 Ib. Bearing stress in UiLj. is 42,200 -j- (6 X 0.89) 

 = 7,900 Ib. Bearing stress in t/iLg is 107,000 4- (6 X IT'S) = 12,400 Ib. per sq. in. The 

 allowable bearing stress was 15,000 Ib. per sq. in. Allowable bearing stresses on pins are given 

 in Table 97. 



For the calculation of the stresses in the pins of a 160 ft. steel highway bridge, see the author's 

 "The Design of Highway Bridges," Chap. XXII, Part III. 



Pin Packing. For details of pin packing see pages 219, 220 and page 402. Details of pins 

 are given in Table 95, Part II. 



Corrugated Steel Roofing. For the calculation of the strength of corrugated steel and for 

 a diagram for the safe loads for corrugated steel, see Fig. 18, Chap. I, page 22. 



Bearing Plates. The bearing plates required for beams and columns, Fig. II, may be deter- 

 mined by the following formulas. 



Let R = reaction of beam or load on column. 

 A = area of bearing plate. 

 w = allowable unit pressure in masonry. 

 / = allowable fiber stress in plate. 

 P = projection of bearing plate beyond any edge of beam or column. 



Area of bearing plate, 



Y/////7/77, 



FIG. ii. BEARING PLATES. 



A-* 



w 



Thickness of bearing plate required by a given projection, 



n$R jyv 



t= HATf = Hj 



Safe projection for a given thickness of plate, 



*-*Viif" < Vw 



(18) 



(19) 



(20) 



The allowable pressures of bearing plates on masonry (value of w) are given in Table VIII, 

 page ^75. Standard bearing plates for I-beams are given in Table 8; for channels in Table 15. 

 The length of I-beams which should bear on plates in order that the full shearing strength be 

 developed is given in Table 11; and of channels in Table 16. 



For a full discussion of bearing plates, see Bulletin No. 35, University of Illinois Engineering 

 Experiment Station, entitled "A Study of Base and Bearing Plates for Columns and Beams," 

 by Professor N. Clifford Ricker. 



COMBINED FLEXURE AND DIRECT STRESS. The formulas for combined flexure and 

 direct stress are given in section 26, Chapter XVI. The design of members stressed in com- 

 bined flexure and direct stress will be shown by several examples. 



Eye-Bar. An eye-bar in a structure carries a direct stress due to the dead and live loads, 

 and in addition is stressed in flexure due to its own weight. 



