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No channel less than ten (10) inches in depth shall be used, except for lateral struts, in which eight (8) inch channels may be employed.
No angles less than 3" X 2 1/2" X 3/8" shall be used, except for lacing.
No eye-bars less than four (4) inches deep or three quarters (3/4) of an inch thick shall be employed; and the depths of eyebars for chords and main diagonals shall not be less than one fifty-fifth (1/55) of the length of the horizontal projection of same.
No adjustable rod shall have less than one square inch of cross-section.
The shortest span length for trusses with polygonal top chords shall be one hundred and seventy-five (175) feet.
The limit of span length in which the stringers can be riveted continuously from end to end of span shall be two hundred (200) feet. Beyond this limit sliding bearings must be used at one or more intermediate panel points; and in no span shall there be a length of continuously riveted stringers exceeding two hundred (200) feet.
For all compression-members of trusses and for columns of viaducts and elevated railroads the greatest ratio of unsupported length to least radius of gyration shall be one hundred (100), excepting those members whose main function is to
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