This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1919 Excerpt: ... the span, equate it to the deflection of the cable and show that the value of f thus found is less than 0.70. Art. 54. Temperature Stresses In Trusses. The effect of changes of temperature upon the cable has been discussed in Art. 46. When the cable elongates the truss must deflect downward thus throwing a part of the ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1919 Excerpt: ... the span, equate it to the deflection of the cable and show that the value of f thus found is less than 0.70. Art. 54. Temperature Stresses In Trusses. The effect of changes of temperature upon the cable has been discussed in Art. 46. When the cable elongates the truss must deflect downward thus throwing a part of the load upon it; when the cable contracts the truss is deflected upward and is also stressed. An approximate investigation will now be made to determine these stresses in the truss having no hinge. Let the hangers be adjusted so that at the standard temperature of 50 degrees there will be no stresses in the truss, all the load being carried by the cable. When the temperature rises / degrees the cable elongates the amount etc, where c is the length of the cable and e is the coefficient of expansion. From Art. 44 the deflection of the cable at the middle of the span is M=-L- =3i (I) 16 J x6s where s is the sag ratio. This must be equal to the deflection of the truss. Let S be the unit-stress in the chords at the middle of the truss, d the depth of the truss, then from the theory of flexure (Mechanics of Materials, Art. 37), 24 Ed which is the deflection at the middle of the truss. Equating the values of Bh given by (1) and (2) there results, after replacing c by its value in terms of / and s, which is the unit-stress in the chords at the middle of the truss, due to a rise or fall of t degrees. When the temperature rises this unit-stress is tension in the lower and compression in the upper chord, when it falls the reverse is the case. It is seen that these stresses are independent of the cross-section of the chords and that they increase with the depth of the truss. For example, let the span be 1000 feet, the sag 80 feet, the depth of the...
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Add this copy of A Text-Book on Roofs and Bridges to cart. $50.04, new condition, Sold by Revaluation Books rated 4.0 out of 5 stars, ships from Exeter, DEVON, UNITED KINGDOM, published 2009 by BiblioBazaar.
