Previous Rule Change | Main Page | Resolution Decision Main Page | Change List for this Rule | Search Decision Number 14-02-015 | Decision Number 14-02-015 | Next Rule Change |

Original Version

Rule 48.1 - Table 5

Table 5

Wood Strengths

Species | Modulus of Rupture Bending (a) | |

Sawed Rectangular Poles, Crossarms, Etc. (b) | Round Poles | |

Cedar, western red | 4,700 lbs per square inch | 6,000 lbs per square inch |

Douglas fir, dense | 6,300 lbs per square inch | 6,800 (c) lbs per square inch |

Douglas fir, not dense | 5,800 lbs per square inch | 6,800 (c) lbs per square inch |

Fir, white or red, local | 4,700 lbs per square inch | 5,600 lbs per square inch |

Pine, southern yellow, dense | 6,300 lbs per square inch | 6,800 (c) lbs per square inch |

Pine, southern yellow, not dense | 5,800 lbs per square inch | 6,800 (c) lbs per square inch |

Redwood, virgin | 5,300 lbs per square inch | 6,200 lbs per square inch |

Redwood, second growth | 3,900 lbs per square inch | 6,200 lbs per square inch |

(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 (Forest 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 (Forest Service Agriculture 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 neutral 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 and 0.85 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. |

Strikeout and Underline Version

Rule 48.1 - Table 5

Table 5

Sample Wood Strengths

Specified in ANSI 05.1-2008

Species | Modulus of Rupture Bending (a) Designated Fiber Strength | |

Sawed Rectangular Poles, Crossarms, Etc. (b) | Round Poles | |

Cedar, western red | 4,700 lbs per square inch | 6,000 lbs per square inch |

Douglas fir, dense | 6,3008,000 lbs per square inch | 6,800 (c) lbs per square inch |

Douglas fir, not dense | 5,800 lbs per square inch | 6,800 (c) lbs per square inch |

Fir, white or red, local | 4,700 lbs per square inch | 56,600 lbs per square inch |

Pine, southern yellow, dense | 6,3008,000 lbs per square inch | 6,800 (c) lbs per square inch |

Pine, southern yellow, not dense | 5,800 lbs per square inch | 6,800 (c) lbs per square inch |

Redwood, virgin | 5,300 lbs per square inch | 6,200 lbs per square inch |

Redwood, second growth | 3,900 lbs per square inch | 6,200 lbs per square inch |

(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 (Forest 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 (Forest Service Agriculture 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 neutral 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 and 0.85 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. |

Final Version

Rule 48.1 - Table 5

Table 5

Sample Wood Strengths

Specified in ANSI 05.1-2008

Species | Designated Fiber Strength |

Cedar, western red | 6,000 lbs per square inch |

Douglas fir | 8,000 lbs per square inch |

Fir, white or red, local | 6,600 lbs per square inch |

Pine, southern | 8,000 lbs per square inch |