CEMP-E
TI 809-07
NOVEMBER 1998
(2) Strength requirements for a brace force of, Fbr as follows for ASD or LRFD design
methods:
( B)
0.004P L
Fbr
(Eq 2-6)
Where:
Fbr = Brace force in consistent units.
P = Share of the gravity load supported by the shear wall frame. Should two frames
support the entire floor load P is the floor load.
L = Length of diagonal brace.
B = Width of the frame bent.
(3) Brace Stiffness will meet the following requirement:
()
C(P) L3
(Eq 2-7)
Ab =
()
E(h) B2
Where:
Ab = Cross sectional area of the brace in consistent units.
C = Constant: ASD = 4, LRFD = 2.67.
P = Share of gravity load supported by the braced frame for lateral stability.
L = Length of diagonal brace.
E = 29,500 Ksi, or 203 395 MPa.
h = Height of braced frame.
B = Width of braced frame.
j. Serviceability Deflection Limits
(1) Live Load Deflections. Deflection criteria for buildings under load are
generally established to ensure functional performance and economy of design. Many of the
deflection limits used today have been established based on past performances and the
perception of the occupants in a building. A consideration for deflection limits is often tied into the
performance of the attached claddings. A stiffer cladding requires a stiffer backup to prevent
damage to the cladding. In the case of floor joists, the limit may be established to reduce
vibrations (see paragraph 2.4.m) which are unacceptable to the occupants. In any case,
consideration should be given to all serviceability issues. The following list is a compilation of
suggested deflection limits by manufacturers, trade groups and building officials that may be
applied to light gauge metal framed structures. The list below assumes limits at full dead plus live
load; full dead plus snow; or full dead plus wind load unless noted otherwise.
Exterior wall finishes
Brick veneer over sheathed framing
L/600
Stucco over sheathed or open framing
L/360
Exterior Insulation Finish Systems
L/240
Cement board sheathing over framing
L/360
Stone (marble, granite, limestone)
VERIFY WITH STONE
SUPPLIER
Plywood and Oriented strand board
L/240
Gypsum sheathing over framing
L/240
Metal or vinyl siding over sheathed framing
L/240
Interior wall finishes
Plaster
L/360
Ceramic tiles
L/360
2-9
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