CIVIL ENGINEERING FORMULAS

BUILDING AND STRUCTURES FORMULAS 233

For deflection determinations, that is, in computing moment of inertia to be
used in deflection calculations or in other calculations involving stiffness,

(9.84)

withf,w, and tthe same as for Eq. (9.83).

Web Stresses in Light-gage Members The shear on the gross web section in
light-gage cold-formed flexural members is usually limited to two-thirds of the
basic working stress in tension and bending, or

(9.85)

whichever is smaller. In this expression h/tis the ratio of depth to web thick-
ness, or of stiffener spacing to web thickness, as for plate-girder construction.
Where the web consists of two sheets, as in the case of two channels fastened
back to back to form an I section, each sheet should be considered as a separate
web carrying its share of the shear.

(9.86)

In solving this formula, Bshould not be assigned any value greater than h.

Pmax(1) 100 t^2  980  42

B

t

0.22

B

t

h

t

0.11

h

t

h h

B

B

Pmax (1)

Pmax (1)

t = web thickness, mm

Overall

depth

H

Overall

depth

H

h = clear distance between flanges, mm

B = length of bearing, mm

H= overall depth, mm

Maximum End Reaction or Concentrated Load on End of Cantilever for

Single Unreinforced Web of Light-gage Steel

(Grade C steel, corner radii = thickness of material)

Shear, psi,v

64,000,000

(h/t)^2

b

t



10,320

f 

1 

2,580

(wt)f