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Abstract
NBS conducted a field study of trenching lumber and found that either ungraded or graded lumber is used. The results of the filed study indicate that 80% of the eastern species trenching lumber, when graded by existing softwood grading rules is No. 2 grade or higher; 60% is No. 1 grade or higher. These percentages do not reflect the effects of wane and decay, which are additional problems. NBS therefore recommends that, for hardwood wales and struts, allowable stresses and other properties be basedon a No. 2 minimum grade with appropriate provisions to control wane and decay. Use recommendations were developed, which consider duration of load, mechanical damage to lumber, presence of bark, decay, insect attack, inspectability, exposure, and storage for various aspects of trenching lumber applications. These recommendations reflect a sever trenching environment, possible reuse of structural members, and the need for structural integrity to protect life and property.
NBS conducted a field study of trenching lumber and found that either ungraded or graded lumber is used. The results of the filed study indicate that 80% of the eastern species trenching lumber, when graded by existing softwood grading rules is No. 2 grade or higher; 60% is No. 1 grade or higher. These percentages do not reflect the effects of wane and decay, which are additional problems. NBS therefore recommends that, for hardwood wales and struts, allowable stresses and other properties be basedon a No. 2 minimum grade with appropriate provisions to control wane and decay. Use recommendations were developed, which consider duration of load, mechanical damage to lumber, presence of bark, decay, insect attack, inspectability, exposure, and storage for various aspects of trenching lumber applications. These recommendations reflect a sever trenching environment, possible reuse of structural members, and the need for structural integrity to protect life and property.
Date
3/1980
3/1980
Author(s)
L Knab; F Yokel; W Galligan; B Bendsten; J Senft
L Knab; F Yokel; W Galligan; B Bendsten; J Senft
Page(s)
221
221
Keyword(s)
construction lumber; safety; excavation; hardwood; lumber grading shoring; softwood; timber engineering; trench bracing; trenching
construction lumber; safety; excavation; hardwood; lumber grading shoring; softwood; timber engineering; trench bracing; trenching