Solid Wood Products 2685 



energy absorbing properties than corresponding sawn posts. Hickory tested 

 highest in average strength, stiffness, and energy absorbing properties, followed 

 by oak, then pine. The modulus of rupture and modulus of elasticity of posts did 

 not increase as much with drying as those of the matching small clear specimens. 

 The creosote preservative treatment did not appreciably affect strength proper- 

 ties of the posts. 



FENCE POSTS 



In a survey of Piedmont farms in Georgia, Worrell and Todd (1955) found 

 only 12 percent of the farms without fences; length of fence on the other 88 

 percent ranged from 700 feet to 90,000 feet, and averaged about 18,000 feet per 

 farm. Data on the number of fence posts installed on farms throughout the 

 southern pine region are not published but the number is very large. Annual 

 purchases of fence posts for replacement and new construction are also 

 substantial. 



Fence post size. — All treated posts sold by commercial plants are graded by 

 size, i.e., according to the diameter at the small end (top), and the length. Two 



Table 22-26 — Average modulus of rupture, modulus of elasticity, and impact energy at 

 failure, of round and sawn posts of three species tested in green condition, at 12-percent 

 moisture content, and when pressure treated with creosote (Doyle and Wilkinson 1969)' 



Modulus Modulus 



of of Impact 



Condition and size rupture^ elasticity^ energy-^ 



Thousand 

 Psi Thousand psi inch-pounds 



HICKORY (MOSTLY MOCKERNUT AND SHAGBARK) 



Green 



3-inch round 13,430 2,080 47.7 



4- by 4-inch sawn 8,350 1 ,050 61.8 



5-inch round 12,580 1,950 134.0 



4- by 6-inch sawn 7,480 1 ,410 107.2 



8-inch round 12,050 1,990 — 



6- by 8-inch round 6,910 1 ,320 — 



Treated 



3-inch round 14,120 2,130 46.2 



4- by 4-inch sawn 9,290 1 ,530 35.9 



5-inch round 12,180 1,820 124.7 



4- by 6-inch sawn 8,140 1,500 120.1 



8-inch round 10,200 1 ,570 — 



6- by 8-inch sawn 7,520 1,410 — 



Dry 



3-inch round 19,500 2,480 60.8 



4- by 4-inch sawn 10,500 1 ,520 37.7 



5-inch round 13,460 1,990 130.4 



4- by 6-inch sawn 12,140 2,020 85.4 



8-inch round 16,540 2,800 — 



6- by 8-inch sawn 12,990 1,840 — 



See footnote page 2686 



