Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

170 Molesworth’s pocket-book Wi;ouuht-ii:o.v Plate Girders. L = Length, of girder (or span) in feet. W — Weight distributed in tons. D = Effective depth of girder in feet. g — strain on top and bottom flange at centre W L [in tons. S nr. ■.— • 8D L ' If the depth = ---, then S = W. „ „ = „ 8 = nw. : BMW In compression, iron may be strained to 4 tons •7»er'square ineh. : / In tension, iron may be strained to 5 tons per square inch. ! y ’ By Board bf Trade regulations, 5 tons per square ipeh in tensiuü 'and •compi’es^ioil. By regulations of the Ponts e| Clianssees, 3’81 tons per square iincli. SaFk Limit of ÉStbess.in Wröught-iron Bhidges. With different proportions of Dead to Live lo^d. S Sate limit in tons per square inch. Dead loai^ 4- live load =c 1 • 0l Unwin. Live load .. I !é • i JU 'øj’-f! 2 •3 ■1 •6 ! •? : •4 -3 •5 '8 '2 •9 1-0 O ( Live load .. I ■ I Dead load .. JI; s/rtl terikon Wtr 3«'5 • 83® ■ 3fc 5 UH • 66,1• 37 4 • 123 • 8Yä-683 • 5 S. ill compn-= •ö