Effect of Footing Width on Bearing Capacity Factor $N_\gamma$ for Smooth Strip Footings

Kumar, Jyant and Khatri, VN (2008) Effect of Footing Width on Bearing Capacity Factor $N_\gamma$ for Smooth Strip Footings. In: Journal of Geotechnical and Geoenvironmental Engineering, 134 (9). pp. 1299-1310.

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Abstract

By incorporating the variation of soil friction angle $\phi$ with mean principal stress $\sigma_m$ the effect of footing width (B) on bearing capacity factor $N_\gamma$ was examined for a smooth strip footing placed on a granular medium without any surcharge pressure. The analysis was performed by means of a numerical lower bound limit analysis in conjunction with finite-elements and linear programming. An iterative computational procedure was framed to account for the dependency of $\phi$ on $\sigma_m$. Two well-defined $\phi-\sigma_m$curves from literature associated with Hoston and Toyora sands, corresponding to relative density of 18 and 74.5%, respectively, were used. The magnitude of $N_\gamma$ was obtained for different footing widths, covering almost the entire range of model and field footing sizes. It was noted that for B greater than about 0.4 m, it is possible to relate $N_\gamma$ with B approximately in a linear fashion on a log–log scale. Further, it was seen that if an average value of $\phi$ along the footing–soil interface is obtained, it is possible to estimate a reasonable magnitude of $N_\gamma$ for a given footing width provided the relationship between $\phi$ and $\sigma_m$ is specified for the given material.

Item Type:	Journal Article
Publication:	Journal of Geotechnical and Geoenvironmental Engineering
Publisher:	American Society of Civil Engineers
Additional Information:	Copyright of this article belongs to American Society of Civil Engineers.
Keywords:	Footings;Bearing capacity;Failures;Foundations;Limit analysis;Numerical analysis;Optimization.
Department/Centre:	Division of Mechanical Sciences > Civil Engineering
Date Deposited:	15 Oct 2008 05:08
Last Modified:	19 Sep 2010 04:50
URI:	http://eprints.iisc.ac.in/id/eprint/16076

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