TESTS OP WESTERN YELLOW PINE CAR SILLS, ETC. 5 



COMPARISON OF RESULTS OF TESTS ON LARGE AND SMALL 



PIECES. 



The ratios of the average strength values in bending of small clear 

 pieces to the average strength values of the sills and joists from 

 which they were taken are shown in Tables 8 and 9. These tables 

 indicate that the difference in strength between large timbers and 

 small clear pieces is considerably smaller for the air-seasoned than for 

 ;he green material. In other words, the increase in strength as the 

 'esult of seasoning is less in the structural sizes than in the clear 

 sticks. This is due to the development of defects in the large timbers 

 luring seasoning. 



In the tests in compression parallel to the grain, only a slight differ- 

 ence was shown between the strength values of the large pieces taken 

 from the sills and those of the small pieces taken from both the sills 

 md joists. This is largely due to the fact that all of the specimens 

 ised in these tests were free from defects. 



?able 4. — Results of bending tests of small clear sticks taken from western 

 yellow pine car sills, 2-inch by 2-inch by 30-inch beams, 28-inch span. 









Weight 



oer cubic 



Fiber 



Modulus 



Number 

 of 



tests. 



Rings, 

 per 

 inch. 



Moisture. 



foot. 



stress at 

 elastic 



limit per 

 square 



of 

 rupture 



per 

 square 



As 



Oven 









tested. 



dry. 



inch. 



inch. 







Per cent. 



Pounds. 



Pounds. 



Pounds. 



Pounds. 



52 



14.9 



36.1 



35.5 



25.6 



3,156 



5,831 



1 



31.0 



126.1 



56.8 



29.4 



4,240 



7,615 



1 



7.5 



24.9 



27.7 



21.7 



2,120 



3,910 



48 



13.6 



11.5 



29.6 



26.6 



6,705 



10,661 



1 



28.0 



13.7 



39.3 



34.6 



9,615 



14, 840 



1 



7.0 



10.2 



24.0 



21.7 



3,762 



7,350 



Modulus 



of 



elasticity 



per 



square 



inch. 



reen: 

 Av 

 Maximum 

 Minimum. 



ir seasoned: 

 Average... 

 Maximum 

 Minimum. 



Thou- 

 sands of 

 pounds. 

 1,178 

 1,680 

 775 



1,442 



1,980 



995 



'able 5. — Results of tests in compression parallel to grain on clear specimens 

 taken from western yellow pine car sills. 





Number 

 of 



tests. 



Rings 

 per 

 inch. 



Moisture. 



Weight per cubic 

 foot. 



Crushing 

 strength 

 at max- 



Seasoning and size of sticks. 



As 

 tested. 



Oven 

 dry. 



imum 

 load per 

 square 



inch. 



reen, 4 inch by 4 inch by 16 inch: 

 Average , 



25 

 23 

 52 

 47 



14.1 

 21.0 

 8.0 



11.5 

 22.0 

 8.0 



14.9 

 31.0 



7.5 



13.5 



28.0 



7.0 



Per cent. 

 43.2 

 80.9 

 27.4 



12.5 

 14.4 

 11.3 



39.4 

 130.4 

 24.0 



11.4 

 15.7 

 10.0 



Pounds. 

 35.9 

 45.7 

 27.4 



29.6 

 34.4 

 24.8 



34.9 

 57.1 

 27.4 



29.9 

 38.5 

 24.2 



Pounds. 

 25.0 

 28.8 

 21.4 



26.3 

 30.5 

 22.1 



25.3 

 29.5 

 20.3 



26.8 

 33.3 

 21.5 



Pounds. 

 2,S30 



Maximum 



3,910 





2,195 



ir-seasoned, 5 inch by 5 inch by 24 inch: 



5,758 



Maximum 



7,002 



Minimum 



4,460 



reen, 2 inch by 2 inch by 8 inch: 

 Average. . .* 



2,896 



Maximum 



3,890 



Minimum 



2,240 



ir-seasoned, 2 inch by 2 inch by 8 inch: 

 Average 



6,334 



Maximum 



S,160 



Minimum 



4,770 







