Instructions on Modern American Bridge Building by G. B. N. (George Bates Nichols) Tower
page 41 of 57 (71%)
page 41 of 57 (71%)
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TABLE OF DIMENSIONS OF A PRATT'S TRUSS. | | | Upper | Lower | Main Brace Rods. | Counter | | | | Clear| | No.| Chord. | Chord. | | Rods. | | | Posts. | Span |Rise| of |---------|---------|--------------------|-----------| | |----------| in | in |Pan-|No.| |No.| |No.| Size |No.|Size.|Num| |No.| Size|No.|Size. | feet.|feet|els.|Pcs|Size.|Pcs|Size.|Ctr|Centre|End| End.|ber| Size. |End| End.|Ctr|Centre| -----|----|----|---|-----|---|-----|---|------|---|-----|---|-------|---|-----|---|------| 25 | 6 | 8 | 3 | 4x5 | 3 | 4x10| 2 |1 | 2 |1-3/8| 1 |1-7/16 | 3 | 4x5 | 3 | 4x4 | 50 | 9 | 9 | 3 | 6x7 | 3 | 6x10| 2 |1-3/16| 2 |1-1/8| 1 |1-5/8 | 3 | 6x6 | 3 | 6x5 | 75 | 12 | 10 | 3 | 6x9 | 3 | 6x11| 2 |1-5/16| 2 |2-1/2| 1 |1-7/8 | 3 | 6x7 | 3 | 6x5 | 100 | 15 | 11 | 3 | 6x10| 3 | 6x12| 2 |1-7/16| 2 |2-7/8| 1 |2 | 3 | 6x9 | 3 | 6x7 | 125 | 18 | 12 | 4 | 6x10| 4 | 6x13| 2 |1-1/2 | 2 |2-3/8| 1 |2-1/8 | 4 | 6x9 | 4 | 6x7 | 150 | 21 | 13 | 4 | 8x10| 4 | 8x14| 3 |1-5/16| 3 |2-1/2| 2 |1-5/8 | 4 | 8x8 | 4 | 8x7 | 175 | 24 | 14 | 4 |10x12| 4 |10x15| 3 |1-5/8 | 3 |2-3/4| 2 |1-11/16| 4 |10x10| 4 | 10x8 | 200 | 27 | 15 | 4 |12x12| 4 |12x16| 3 |1-1/2 | 3 |3-1/8| 2 |1-13/16| 4 |12x10| 4 | 10x8 | This table is partly given in Trautwine's Engineer's Pocket Book, and partly made up from directions therein given. TABLE OF DIMENSIONS FOR SMALL SINGLE TRACK PRATT TRUSSES. At centre At end Centre End Clear Chords Centre End of truss, of truss, Counter, Counter, Span, each, Post, Posts, Diam. of Diam. of Diameter, Diameter, Ft. Ins. Ins. Ins. Rods. Rods. Ins. Ins. 30 9 x 11 4 x 9 7 x 9 1 1-5/8 1-3/8 1 |
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