12_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011

12_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011 -...

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813 (note that m and n are interchangeable in the formula) L .. n=Uz m = Biz Rectangular Surface Loads: (Boussinesq solution - the limn" method» o This method determines the vertical stress ~ay at a point P under the corner of a rectangular loaded area using footing dimensions normalized to the depth z: The sin- 1 quantity is calculated in radians (not degrees). o Fortunately the above formula is also presented in both charts (handout) and tables (Das). o Example 1: Find the stress increase beneath the footing corner (P) at a depth of 6 ft. 'r,,/I, ,1 [;';::i:~~~:;ni 3' ~: ~~ ;:;:'~o;: P ':::':::':':::::::"::::·~:::Y:.I~:::::::::.' Go to chart, find I == 0.' ';). 6' l Plan ... ~av = 6. p.O lUll\) fJ ,) = 1.10 ~ divide into 2 halves multiply solution x 2 Find the stress increase beneath the middle of the long edge a footing (8) at a depth of 6 ft. ,J I \)S£ tf,17' ~\.JfJfflfus Solution: o The integration of the Boussinesq point formula over various loaded areas implies that the
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Unformatted text preview: influence of a one given load does not affect another. This works because the soil is assumed to be linear elastic, and therefore the effects may be "superposed". Superposition may be carried further and used to superpose entire loaded areas - say two circular footings, or a circular footing and square footing. Superposition effects may also be additive or subtractive. Superposition is very powerful because it allows analysis of complex footing shapes using only basic geometrical shapes (point, rectangle, circle). Symmetry may also be used to determine the load beneath other shapes (say a semicircle or a triangle). o Example 2: m = Biz = 3/6 = 0.5 n = Uz = 3/6 = 0.5 in chart find I = 0.084 A~: J. (.01") (I.oofSf) 3' 3' S ~~, ~~~3 3' 8 3'...
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This note was uploaded on 02/10/2012 for the course CEG 4012 taught by Professor Staff during the Fall '08 term at University of Florida.

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