34 BULLETIN 1259, U. S. DEPARTMENT OF AGEICULTUEE. 
single flange between consecutive connections will be 
smaller than this ratio for the member as a whole. 
Shapes of equivalent strength may be used instead of 
flats. 
at pin?^* '^'^'°'' Pin-connected riveted tension members shall have a net 
section, both through the pinhole and back of the pinhole, 
at least 25 per cent in excess of the net section of the body 
of the member. 
of dve?ed ffnsioS ^^ Calculating the required area of riveted tension mem- 
members, bers, net sections shall be used in all cases, and in deduct- 
ing rivet holes they shall be taken as 3/s inch larger than 
the nominal diameter of the rivet. 
The net section shall be the least area which can be 
obtained by deducting from the gross sectional area the 
area of holes cut by any straight or zigzag section across 
the member, coimting the full area of the first hole and a 
fractional part of each succeeding hole, the fractional part 
being determined by the formula : 
iS'2 
4gTi 
where X= fraction of rivet hole to be deducted. 
/S'^ stagger or longitudinal spacing of rivet with 
respect to rivet on last gauge line. 
^ = distance between gauge Tines, or transverse 
spacing. 
^ = diameter of rivet holes, or nominal diameter of 
rivet plus Y^ inch, 
pi^*. ^"''^^'"^ °^ Pins shall be located, with respect to the neutral axes 
of the members, so as to reduce to a minimum secondary 
stresses due to bending. 
36. Pin plates. Pin platcs shall be of sufficient thickness to provide the 
required bearing area upon the pin; they shall be as wide 
as the dimensions of the member vnW allow, and their 
length, measured from pin center to end, shall be at least 
equal to their width. Pin plates shall contain sufficient 
rivets to distribute their due proportion of the pin pres- 
sure to the full cross section of the members; only the 
rivets located witliin two lines drawn from the pin center 
toward the body of the member and inclined at 45 degrees 
to the axis of the member shall be considered effective for 
this purpose. In the case of members composed of web 
plates and flange angles (with or without a cover plate) 
there shall be at least one outside pin plate covering the 
vertical legs of the flange angles. 
At the ends of compression members at least one pair 
of pin plates shall extend not less than 6 inches be3^ond 
the near edge of the tie plate. 
All pin-connected compression members shall be pro- 
vided with hinge plates having a minimum thickness of ^ 
inch. 
37. F or k e d Forked ends on compression members will be permitted 
®^^" only when unavoidable. When used a sufficient number 
