100_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011

100_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011 -...

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a effective area, A' = e,' L' L' = L I II I .. '4 B' = B-2e 2eB BC15 o Meyerhof (1953) proposed an approximation to the above analysis using an "effective area" for the footing based on an "effective width", B', or an "effective length", L', (depending on the direction of the eccentricity). The analysis shown here is for 1-0 eccentricity (el or eB). I ,e.,! "at,: Example: B = 4', l = 6' el X Y B' l' 0.5' 4' 5' 4' 5' l' 4' 4' 4' 4' 2' 4' 2' 2' 4' I. ~, Analysis Procedure: 1. Calculate X = B - 2eB and Y = L - 2el 2. Assign X and Y to B' and l'. B' is the shortest dimension and l' is the longest. 3. Note that e max = 0.5 because this will give B' (or l') = O. Usual design limit is e s B/6 (or e S U6) to keep resultant in center 1/3 of footing (best approximation by this method). 4. Use BC equation as follows: I Qu= CNcAcsAcdAci
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Unformatted text preview: + gNgA.asA.adA.a1 + V2 yB'NyA,sA.m?\J use B = B' with Ny term use B' and l' for calculation of shape factors Acs, A.qs, ~ use actual B for calculation of depth factors Acd, A.qd' "-¥d 5. Use the effective area to calculate the bearing capacity Q u = quA' = quB'l' The concept of effective area can be applied to circular footings and 2-D eccentricity. These problems are solved for effective dimensions so that the resultant load acts at the centroid of the effective area. (This is true of the above 1-0 problems which are much easier to calculate.) For clays (cjl = 0) the bearing capacity decreases linearly with e. For sands (c = 0) the effect is parabolic. See next page....
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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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