dead loads and idealization of structural members 4 presentation f18 w… · construct dead load...
TRANSCRIPT
Dead Loads and Idealization of Structural Members
StevenVukazichSanJoseStateUniversity
Dead Loads are Fixed Position Gravity LoadsExamples are weights of the following:
• Ceiling,• Flooring,• Façade,• Structural Members.
Found from tables of weights of building materials (usually listed in weight/unit area)
What is a Dead Load?
Load Path
MetalDeck
Beams(e.g.W14x22)
GirdersorTruss(e.g.W18x50)
Columns
Foundation
A
B
C
D
1 2 3
22’-0” 22’-0” 1’-6”1’-6”1’-6”
18’-0”
18’-0”
18’-0”
1’-6”
6’-0” typ.W14x22
W14x22
W18x46
W14x22
W14x22
W18x46
W14x22
W14x22
W18x46
W18x46W14x22
W14x22
DO
DO
DO
DO
DO
DO
DO
DO
W18
x50
W18
x50
W18
x50
W18
x50
W18
x50
W18
x50
W18
x50
Dbl
6x6
1-1/2” 18 gaugemetal deck typ.
Dead Load tables are usually constructed using the load path
Section onnext slide
Construct Dead Load Table for Roof Framing
1-1/2” 18 gaugemetal deck
2” rigid fiberglass insulation
3 ply felt tar and gravel roofing
6’ - 0” 6’ - 0” 6’ - 0”
W14x22
spray-on fireproofing
ceiling
HVAC duct (mechanical)
Cross Section of Roof
Ceiling Support Hangers from Steel Framing at New Rec Center
Load Path →
Material To metal
deck To beams (W14x22)
To girders, truss (Lines 1-3)
To columns
1-1/2” 18 gauge metal deck
2.82 (A) 2.82 2.82 2.82
Fireproofing 0.5 0.5 0.5 0.5
2” Rigid fiberglass insulation
3 (B) 3 3 3
3 ply felt tar and gravel roofing
5.5 (B) 5.5 5.5 5.5
Ceiling and Lighting 1 (B) 1 1 1 W14x22 @ 6 ft o.c. 3.7 (C) 3.7 3.7 Mechanical (plumbing, HVAC)
4 4 4
W18x50, truss 4 4 Weight of columns 1 Misc. 3 3 3 3 Total 15.82 23.52 27.52 28.52 Use 16 psf 24 psf 28 psf 29 psf Notes:
A. From Vulcraft deck catalog. B. From AISC steel manual “Weights of Building Materials”. C. W14x22: (22 lb/ft)/(6 ft) = 3.7 psf.
Construct Dead Load Table
Weights of Building Materials from AISC Manual of Steel Construction
Loads carried to the beam from the metal deck are uniformly distributed over the beam
Deck Carries Uniform Load to Beams
Loads carried to the larger beam (girder) from the smaller beams are concentrated at the point of the connection and applied as point loads
Vertical (Gravity) Load Path
Framingatoverhangingdeckcarriesloadtogirderatedge
Framing at Deck Overhang
A
B
C
D
1 2 3
22’-0” 22’-0”
1’-6”1’-6”
1’-6”
18’-0”
18’-0”
18’-0”
6’-0” typ.
W14x22
W14x22
W18x46
W18x46
W14x22
W14x22
W18x46
W18x46W14x22
W14x22
DO
DO
DO
DO
DO
W18
x50
W18
x50
W18
x50
W18
x50
W18
x50
W18
x50
W14x22
Uniformly distributed dead load based on 24 psf
Point dead load based on 28 psf
Idealization of Structural Members