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Fig. 8.8 Effective widths and area. Inclined loads

The usual method of dealing with an inclined line load, such as P in Fig. 8.9, is to first determine its horizontal and vertical components PH and Pv and then, by taking moments, determine its eccentricity, e, in order that the effective width of the foundation B' can be determined, from the formula B' = B — 2e.

The ultimate bearing capacity of the strip foundation (of width B) is then taken to be equal to that of a strip foundation of width B' subjected to a concentric load, P, inclined at a to the vertical.

Various methods of solution have been proposed for this problem, e.g. Janbu (1957), Hansen (1957) but possibly the simplest approach is that proposed by Meyerhof (1953) in which the bearing capacity coefficients Nc, Nq and Ny are reduced by multiplying them by the factors Ic, Iq and I7 in his general equation (10). Meyerhof's expressions for these factors are:

Fig. 8.9 Strip foundation with inclined load.

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