Page 97 - Handbook of Civil Engineering Calculations, Second Edition

1.80 STRUCTURAL STEEL ENGINEERING AND DESIGN

2. Compute the tensile capacity of the plate
The tensile capacity P t lb (N) of plate A (Fig. 55) is required. In structural fabrication, riv-
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et holes are usually punched /16 in. (1.59 mm) larger than the rivet diameter. However, to
allow for damage to the adjacent metal caused by punching, the effective diameter of the
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hole is considered to be /8 in. (3.18 mm) larger than the rivet diameter.
Refer to Fig. 55b, c, and d. Equate the tensile stress at each row of rivets to 22,000
lb/sq.in. (151,690.0 kPa) to obtain P t . Thus, at aa, residual tension P t net area (9
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0.875)(0.375) 3.05 sq.in. (19.679 cm ). The stress s P t /3.05 22,000 lb/sq.in.
(151,690.0 kPa); P t 67,100 lb (298,460.0 N).
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At bb, residual tension /9P t net area (9 1.75)(0.375) 2.72 sq.in. (17.549 cm );
s /9P t /2.72 22,000; P t 67,300 lb (299,350.0 N).
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At cc, residual tension /3P t net area (9 2.625)(0.375) 2.39 sq.in. (15.420 cm );
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s /3P t /2.39 22,000; P t 78,900 lb (350,947.0 N).
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3. Select the lowest of the five computed values
as the allowable load
Thus, P 59,700 lb (265,545.6 N).
DESIGN OF A BUTT SPLICE
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A tension member in the form of a 10 /2 in. (254.0 12.7 mm) steel plate is to be
spliced with /8-in. (22.23-mm) rivets. Design a butt splice for the maximum load the
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member may carry.

Calculation Procedure:
1. Establish the design load
In a butt splice, the load is transmitted from one member to another through two auxiliary
plates called cover, strap, or splice plates. The rivets are therefore in double shear.
Establish the design load, P lb (N), by computing the allowable load at a cross section
having one rivet hole. Thus net area (10 1)(0.5) 4.5 sq.in. (29.03 cm ). Then P
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4.5(22,000) 99,000 lb (440,352.0 N).
2. Determine the number of rivets required
Applying the values of rivet capacity found in an earlier calculation procedure in this sec-
tion of the handbook, determine the number of rivets required. Thus, since the rivets are
in double shear, R ds 18,040 lb (80,241.9 N); R b 42,440(0.5) 21,220 lb (94,386.6
N). Then 99,000/18,040 5.5 rivets; use the next largest whole number, or 6 rivets.
3. Select a trial pattern for the rivets; investigate the tensile stress
Conduct this investigation of the tensile stress in the main plate at each row of rivets.
The trial pattern is shown in Fig. 56. The rivet spacing satisfies the requirements of the
AISC Specification. Record the calculations as shown:

Residual tension in Net area,
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Section main plate, lb (N) ÷ sq.in. (cm ) Stress, lb/in (kPa)
aa 99,000 (440,352.0) 4.5 (29.03) 22,000 (151,690.0)
bb 82,500 (366,960.0) 4.0 (25.81) 20,600 (142,037.0)
cc 49,500 (220,176.0) 3.5 (22.58) 14,100 (97,219.5)