Handbook of Civil Engineering Calculations

However, B cannot be less than the flange width of the W21 x 62 beam, Zy= 8.24. Round-

ing 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:

12.22Rn^2

V A 1 Fy

Where R = 100 kips (444.8 kN)

B-2k 9in-2x Iy 8 Jn

n = —-— = = 3.13 in (7.95 cm)

A 1 = BN= 9 in x 9 in = 81 in^2 (522.6 cm^2 )

Fy = 36 ksi (248 MPa)

3. Select the bearing-plate dimensions

t=^1 2.22x100 kipsx(3.13J^= 2

V 81m

2

x36ksi

Use a bearing plate 1 in x 9 in x 9 in (2.54 x 22.9 x 22.9 cm)

Related Calculations. This procedure is the work of Abraham J. Rokach, MSCE,
Associate 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 x 62 beam to bear directly on the concrete support, its bottom flange must be
   sufficiently thick to act as a bearing plate. Let

t=

2

'

22Rn2

=0.615 in (1.56 cm)

V A\Fy

the flange thickness of the W21 x 62 beam. Because B = bf = 8.24 in (20.9 cm)

B-2k 8.24 in-2 x \%'m. _.. ,, 00 ,

n = = = 2.75 m (6.99 cm)

/2.22 x 100 kips x (2.75 in)^2 " .„.. „ ., ,

t= / —.—V^ — =0.615 in(1.56 cm)

V A 1 x36kips/m^2 v '