Page 182 - Handbook of Civil Engineering Calculations, Second Edition

STRUCTURAL STEEL DESIGN 1.165

However, B cannot be less than the flange width of the W21 62 beam, b f 8.24.
Rounding up, let B 9 in. (22.9 cm). A formula for bearing plate thickness is given on
page 3.50 of the AISC LRFD Manual:
2
2.22Rn
t
A 1 F y
where R 100 kips (444.8 kN)

B – 2k 9 in. – 2 × 1 /8 in.
3
n = 3.13 in. (7.95 cm)
2 2
2
A 1 BN 9 in. 9 in. 81 sq.in. (522.6 cm )
F y 36 ksi (248 MPa)

3. Select the bearing-plate dimensions

t 2.22 × 100 kips × (3.13 in.) 2 0.86 in. (2.18 cm)
81 sq.in. × 36 ksi
Use a bearing plate 1 in. 9 in. 9 in. (2.54 22.9 22.9 cm).

Related Calculations. This procedure is the work of Abraham J. Rokach, MSCE, As-
sociate Director of Education, American Institute of Steel Construction. SI values were
prepared by the handbook editor.

DETERMINING BEAM LENGTH TO
ELIMINATE BEARING PLATE

Determine if the bearing plate chosen in the preceeding procedure can be eliminated by
altering the design.

Calculation Procedure:

1. Compute the needed thickness of the bottom flange
For the W21 62 beam to bear directly on the concrete support, its bottom flange must
be sufficiently thick to act as a bearing plate. Let

2
2.22Rn
t 0.615 in. (1.56 cm)
A 1 F y
the flange thickness of the W21 62 beam. Because B b f 8.24 in. (20.9 cm)

B – 2k 8.24 in. – 2 × 1 /8 in.
3
n 2.75 in. (6.99 cm)
2 2