INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS Int. J. Numer. Anal. Meth. Geomech. 2008; 32:1417–1426 Published online 28 December 2007 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/nag.677 SHORT COMMUNICATION Ultimate bearing capacity of equally spaced multiple strip footings on cohesionless soils without surcharge K. M. Kouzer ‡ and Jyant Kumar ∗, †, § Department of Civil Engineering, Indian Institute of Science, Bangalore 560012, India SUMMARY The ultimate bearing capacity of a group of equally spaced multiple rough strip footings was determined due to the contribution of soil unit weight. The analysis was performed by using an upper bound theorem of limit analysis in combination with finite elements and linear programming. Along the interfaces of all the triangular elements, velocity discontinuities were considered. The value of   was found to increase continuously with a decrease in S/ B, where (i)   is the ratio of the failure load of an interfering strip footing of a given width ( B) to that of a single isolated strip footing having the same width and (ii) S is the clear spacing between any two adjacent footings. The effect of the variation of spacing on   was found to be very extensive for small values of S/ B;   approaches infinity at S/ B = 0. In all the cases, the velocity discontinuities were found to exist generally in a zone only around the footing edge. Copyright 2008 John Wiley & Sons, Ltd. Received 1 May 2007; Revised 1 October 2007; Accepted 19 November 2007 KEY WORDS: bearing capacity; failure load; finite element; foundations; limit analysis 1. INTRODUCTION A number of theories have been developed in literature to determine the ultimate bearing capacity for a group of two strip footings. The existing solutions were obtained based on (i) the limit equilibrium method [1], (ii) the method of stress characteristics [2], and (iii) the upper bound limit analysis [3, 4]. A few small-scale model tests have also been performed by different researchers ∗ Correspondence to: Jyant Kumar, Department of Civil Engineering, Indian Institute of Science, Bangalore 560012, India. † E-mail: jkumar@civil.iisc.ernet.in ‡ QIP Research Scholar. § Associate Professor. Copyright 2008 John Wiley & Sons, Ltd.