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BELL SYSTEM TECHNICAL JOURNAL 



inches (viz. 348.6 x 180), which exceeds the 57,120 pound-inches resisting 

 moment at the center (viz. 9.52 inches^ x 6000 psi). This means that the 



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DISTANCE FROM CENTER IN INCHES 



Fig. 2 — Moment diagrams for a beveled lOB crossarm: 

 Graph 1 — Resisting moments of a clear,straight grained, 3.25" x 4.25" arm. Fiber 



stress assumed to be 6000 psi ; 

 Graph 2 — Bending moments from a concentrated load of 871.5 pounds at end pin hole; 

 Graph 3 — Bending moments from a load of 348.6 pounds at each pin hole; and 

 Graph 4 — Bending moments from a load of 317.3 pounds at each pin hole. 



arm would fail under such loading; and that the critical section of the arm 

 under loads distributed at each pin hole is not at the pole pin holes but at 

 the center of the arm. The maximum load per pin that the arm would 



