Page 219 - สะพานเครื่องหนุนมั่น

ข - 4

Appendix E-2. Allowable Unit Stresses for Timber

Extreme fiber Shear parallel Bearing per- Compression Modulus of
in bending or to grain pendicular to parallel to elasticity
Spectal 1 tension par- grain grain or
allel to grain f = 0.45E
c
(L/d) 2
(psl) (psl) (psl) (psl) (psl)

SOFTWOOD LUMBER

Baldeypress (eypress) 2850 225 440 2125 1,200,000
Cedar :
Alaska 2400 195 370 1575 1,200,000
Atlantic White (southern white cedar) and northern white 1650 150 260 1125 800,000
Port-Orford 2400 195 370 1800 1,500,000
Western red ceder 1950 180 290 1425 1,000,000
Douglas fir :
Coast-type 3300 195 470 2175 1,600,000
Coast-type, close grained 3525 195 500 2324 1,600,000
Rocky Mountain type 2400 180 410 1575 1,200,000
All types, dense 3825 195 550 2550 1,600,000
Fir :
Balsam 1950 150 220 1425 1,000,000
California red, gran gran,noble and white 2400 150 440 1425 1,100,000
Hemlock :
Eastern 2400 150 440 1425 1,100,000
Western (west coast hemlock) 2850 165 440 1800 1,400,000

SOFTWOOD LUMBER

Larch, western 3300 195 470 2175 1,200,000
Pine :
Eastern white (northern white), ponderosa, sugar, and
western white (Idaho white) 1950 180 370 1500 1,000,000
Jack 2400 180 320 1575 1,100,000
Lodgepole 1950 135 320 1425 1,100,000
Red (Norway pine) 2400 180 320 1575 1,200,000
Southern yellow 3300 240 470 2175 1,600,000
Dense 3825 240 550 2550 1,600,000
Redwood 2625 150 370 2025 1,200,000
Closse-greined 2850 150 390 2175 1,200,000
Mapie, black and sugar (hard maple) 3300 275 730 2400 1,600,000
Oak, commercial red and white 3075 275 730 2025 1,500,000
Sweetgum (gum, red gum, sap gum 2400 225 440 1575 1,200,000
Tupelo, black (black rum) and water 2400 225 440 1575 1,200,000
Yellow-poplar (poplar) 2175 195 320 1575 1,200,000
1 Species names approved by U.S. Forest Sarvice. Commercial designations are shown in parentheses.