Handbook of Civil Engineering Calculations

to F, s = 3 in (76.2 mm), g = 2.5 in (63.50 mm); WAC = 7- 0.875 = 6.12 in (155.45 mm);
WABDE =? ~ 2(0.875) + 1.25^2 /[4(2.5)] = 5.41 in (137.414 mm); WABDFG = 7 - 3(0.875) +
1.25^2 /(4 x 2.5) + 32 /(4 x 2.5) = 5.43 in (137.922 mm); wmax = 0.85(7) = 5.95 in (151.13
mm). Selecting the lowest value gives weff = 5.41 in (137.414 mm).

2. Compute the tensile stress on the effective net section
   Thus,/= 18,000/[5.41(0.25)] - 13,300 lb/in^2 (91,703.5 kPa).

DESIGN OF A DOUBLE-ANGLE

TENSION MEMBER

The bottom chord of a roof truss sustains a tensile force of 141 kps (627.2 kN). The mem-
ber will be spliced with %-in (19.05-mm) rivets as shown in Fig. 18a. Design a double-
angle member and specify the minimum rivet pitch.

Splice plate

•Bottom-chord angle

Splice plate

(a) Method of splicing

Cut outstanding teg

and place it here

(b) Development of angle for net section

FIGURE 18