Original Version
Rule 48.1- Table 5
|
Wood Strengths |
||
|
Species |
Modulus of rupture in bending |
|
|
Sawed rectangular poles, crossarms, etc. (a) |
Round Poles |
|
|
Cedar. western red |
4,700 lbs. per sq. in. |
6,000 lbs. per sq. in. |
|
Douglas fir, dense |
6,300 lbs. per sq. in. |
6,800 (b) lbs. per sq. in. |
|
Douglas fir, not dense |
5,800 lbs. per sq. in. |
6,800 (b) lbs. per sq. in. |
|
Fir, white or red, local |
4,700 lbs. per sq. in. |
5,600 lbs. per sq. in. |
|
Pine, southern yellow, dense |
6,300 lbs. per sq. in. |
6,800 (b) lbs. per sq. in. |
|
Pine, southern yellow, not dense |
5,800 lbs. per sq. in. |
6,800 (b) lbs. per sq. in. |
|
Redwood, virgin |
5,300 lbs. per sq. in. |
6,200 lbs. per sq. in. |
|
Redwood, second growth |
3,900 lbs. per sq. in. |
4,600 lbs. per sq. in. |
(a) Figures given are for select structural grade of material under short
time loading with the neutral plane parallel to a side. Multiply the values
shown by 1.4 where the neutta1 plane is on the diagonal of a square. Multiply
the given values by 0.55 where the loading being considered is a long time
loading (continuous load for one year or more).
(b)
Where poles meet specifications of American Standards Association, 05.1-1979
for Douglas fir poles and Southern pine poles, this value may be increased
to not more than 8,000 lbs per square inch. Such poles shall be given
suitable preservative treatment.
Strikeout and Underline Version
Rule 48.1- Table 5
Wood Strengths
|
Wood Strengths |
||
|
Species |
Modulus of rupture in bending (a) |
|
|
Sawed rectangular poles, crossarms, etc.
|
Round Poles |
|
|
Cedar. western red |
4,700 lbs. per sq. in. |
6,000 lbs. per sq. in. |
|
Douglas fir, dense |
6,300 lbs. per sq. in. |
6,800 |
|
Douglas fir, not dense |
5,800 lbs. per sq. in. |
6,800 |
|
Fir, white or red, local |
4,700 lbs. per sq. in. |
5,600 lbs. per sq. in. |
|
Pine, southern yellow, dense |
6,300 lbs. per sq. in. |
6,800 |
|
Pine, southern yellow, not dense |
5,800 lbs. per sq. in. |
6,800 |
|
Redwood, virgin |
5,300 lbs. per sq. in. |
6,200 lbs. per sq. in. |
|
Redwood, second growth |
3,900 lbs. per sq. in. |
4,600 lbs. per sq. in. |
(a) Modulus of Rupture in Bending is based on the values for green wood as
determined by the criteria and referenced standards in the United States
Department of Agriculture (USDA) wood Handbook: wood as an Engineering Material
(Forrest Service Agricultural Handbook 72). Green Wood is defined as
freshly sawed or undried (unseasoned) wood. For woods not specifically
listed in the table, other references, such as the USDA Tropical Timbers
of the World (Forrest Service Agricultural Handbook 607), may be used as
long as the methods of testing meet or exceed the criteria and referenced
standards specified in the USDA Handbook 72.
(a) (b)
Figures given are for select structural grade
of material under short time loading with the neutral plane parallel to a
side. Multiply the values shown by 1.4 where the neutta1 plane is on the
diagonal of a square. Multiply the given values by 0.55 where the loading
being considered is a long time loading (continuous load for one year or
more). Also, sawed rectangular poles, crossarms, etc. must be derated
by a factor based on how “dense” or “not dense” the wood is, and whether
the wood comes from second growth. This is known as the density rule,
which uses the percentage of latewood and number of growth rings per inch
of radius (rate of growth). Typical factors are about 0.925 for “dense”
wood 08.85 for “not dense” wood. However the appropriate factor must
be determined for each species of wood used, taking into account the locations
and the conditions in which the trees were grown.
(c) (b)
Where poles meet specifications of American
National Standards Institute, Inc. Association, 05.1 1992
1979 for Wood Douglas fir poles and Southern
pine poles, this value may be increased to not more than 8.000 lbs.
per square inch. Such poles shall be given suitable preservative treatment.
Final Version
Rule 48.1- Table 5
Wood Strengths
|
Wood Strengths |
||
|
Species |
Modulus of rupture in bending (a) |
|
|
Sawed rectangular poles, crossarms, etc. (b) |
Round Poles |
|
|
Cedar. western red |
4,700 lbs. per sq. in. |
6,000 lbs. per sq. in. |
|
Douglas fir, dense |
6,300 lbs. per sq. in. |
6,800 (c) lbs. per sq. in. |
|
Douglas fir, not dense |
5,800 lbs. per sq. in. |
6,800 (c) lbs. per sq. in. |
|
Fir, white or red, local |
4,700 lbs. per sq. in. |
5,600 lbs. per sq. in. |
|
Pine, southern yellow, dense |
6,300 lbs. per sq. in. |
6,800 (c) lbs. per sq. in. |
|
Pine, southern yellow, not dense |
5,800 lbs. per sq. in. |
6,800 (c) lbs. per sq. in. |
|
Redwood, virgin |
5,300 lbs. per sq. in. |
6,200 lbs. per sq. in. |
|
Redwood, second growth |
3,900 lbs. per sq. in. |
4,600 lbs. per sq. in. |
(a) Modulus of Rupture in Bending is based on the values for green wood as determined by the criteria and referenced standards in the United States Department of Agriculture (USDA) wood Handbook: wood as an Engineering Material (Forrest Service Agricultural Handbook 72). Green Wood is defined as freshly sawed or undried (unseasoned) wood. For woods not specifically listed in the table, other references, such as the USDA Tropical Timbers of the World (Forrest Service Agricultural Handbook 607), may be used as long as the methods of testing meet or exceed the criteria and referenced standards specified in the USDA Handbook 72.
(b)
Figures given are for select structural grade of material under short
time loading with the neutral plane parallel to a side. Multiply the values
shown by 1.4 where the neutta1 plane is on the diagonal of a square. Multiply
the given values by 0.55 where the loading being considered is a long time
loading (continuous load for one year or more). Also, sawed rectangular
poles, crossarms, etc. must be derated by a factor based on how “dense” or
“not dense” the wood is, and whether the wood comes from second growth.
This is known as the density rule, which uses the percentage of latewood
and number of growth rings per inch of radius (rate of growth). Typical
factors are about 0.925 for “dense” wood 08.85 for “not dense” wood.
However the appropriate factor must be determined for each species of wood
used, taking into account the locations and the conditions in which the trees
were grown.
(c)
Where poles meet specifications of American National Standards Institute,
Inc. 05.1 1992 for Wood poles this value may be increased to not more than
8.000 lbs. per square inch. Such poles shall be given suitable preservative
treatment.