. The Bell System technical journal . t at Top Knot below Top Segment (Inches) (Inches^) (Inches) A study of this summary shows that knots 1^ and over are more dam-aging when located at the section top; and that knots under 1§ are moredamaging when located immediately below the top segment. The sectionmodulus values associated with 2| and 3 knots would be the same asshown in the Calculation 1 results (Table 1). By a similar analysis for arms of nominal size it can be shown: (1) That the more damaging position for knots 1| and under is imme-diate
. The Bell System technical journal . t at Top Knot below Top Segment (Inches) (Inches^) (Inches) A study of this summary shows that knots 1^ and over are more dam-aging when located at the section top; and that knots under 1§ are moredamaging when located immediately below the top segment. The sectionmodulus values associated with 2| and 3 knots would be the same asshown in the Calculation 1 results (Table 1). By a similar analysis for arms of nominal size it can be shown: (1) That the more damaging position for knots 1| and under is imme-diately below- the top segment; (2) That the more damaging position for any knot within the diameterrange from to and all the larger knots is at the top of thesection; 34 BELL SYSTEM TECHNICAL JOURNAL (3) That the section modulus associated with to knots wouldbe ?:?5y#^ = ; and 0 (4) That the section modulus values associated with 2| and 3 knotswould be the same as shown in the Calculation 1 results (Table 1).. KNOT DIAMETER Fig. 6—Brace bolt hole sections. Section modulus of crossarm sections containing knotsof the sizes shown on the base line and located in damaging positions. The results of Calculation 6 (Table 3), and of the foregoing analyses,together with the Calculation 1 results for 2| and 3 knots, were plotted inFig. 6 for both minimum and nominal sections. t RELATIVE BEXDIXG STREXGTII OF CROSSARMS 35 Rectangular Pole Bolt Hole Section The most damaging position for knots in the pole bolt hole section wasassumed to be at the top of the section. rhe\- were so ligured in Calcula- gip^^flHIHHgtaSHHfH^^ ^- 35 a o Z o I- 4 \ 0 Ft:U:::^rt: CURVE I FOR 3:i:» 4^ SECTIONSCURVE 2 FOR 3^x 4^ SECTIONS
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