Building Design and Construction Handbook - Merritt - Ventech!

COLD-FORMED STEEL CONSTRUCTION 8.23
8.12 ALLOWABLE SHEAR STRENGTH IN WEBS
The shear V, kips, at any section should not exceed the allowable shear V a, kips,
calculated as follows:
For h/t � 0.96�k E/F ,
v y
For 0.96�kvE/Fy� h/t � 1.415�kvE/F
y,
For h/t � 1.415�k E/F ,
v y
V � 0.4F ht (8.17)
a y
2 Va � 0.38t �kvEF y
(8.18)
3
Va � 0.54kvEt /h (8.19)
where t � web thickness, in
h � depth of the flat portion of the web measured along the plane of the
web, in
E � modulus of elasticity of the steel � 29,500 ksi
kv � shear buckling coefficient � 5.34 for unreinforced webs for which
(h/t) does not exceed 200
max
F y � specified yield stress of the steel, ksi
For design of reinforced webs, especially when h/t exceeds 200, see AISI ‘‘Specification
for the Design of Cold-Formed Steel Structural Members.’’
For a web consisting of two or more sheets, each sheet should be considered as
a separate element carrying its share of the shear.
For beams with unreinforced webs, the moment M and shear V should satisfy
the following interaction equation:
where M �
axo
2 2
(M/M axo) � (V/V a)
� 1.0 (8.20)
allowable moment about the centroidal axis, in-kips, when bending
alone is present
V a � allowable shear, kips, when shear alone exists
M � applied bending moment, in-kips
V � actual shear, kips
In addition to above, web crippling should also be checked.
8.13 CONCENTRICALLY LOADED
COMPRESSION MEMBERS
The following formulas apply to members in which the resultant of all loads acting
on a member is an axial load passing through the centroid of the effective section
(calculated at the nominal buckling stress F n, ksi). The axial load should not exceed
P a, kips, calculated from
P � P /� (8.21)
a n c