Shape effects on the capacity of rectangular footings under general loading

Ultimate limit states under vertical (V), moment (M) and horizontal (H) loading of rectangular footings with varying breadth-to-length aspect ratios (B/L) are compared with predictions for plane-strain conditions. Footing/soil interfaces unable to sustain tension and with unlimited tensile resistance are considered. Finite element and analytical predictions are reported, and results are presented as failure envelopes in VH, VM and VMH load space. Vertical and moment capacity of rectangular footings, with either zero or unlimited tension interfaces, is shown to increase with reducing footing length, for foundations of a given bearing area. For footings unable to sustain tension, footing aspect ratio does not affect the shape of the failure envelope: therefore ultimate limit states of a footing of any aspect ratio can be derived from a unique envelope scaled by the appropriate ultimate limit loads defining its apex points. A closed-form expression is proposed to describe the shape of the normalised VMH enve...

[1]  John P. Carter,et al.  Numerical studies of the bearing capacity of shallow foundations on cohesive soil subjected to combined loading , 2000 .

[2]  J. D. Murff,et al.  P-ULTIMATE FOR UNDRAINED ANALYSIS OF LATERALLY LOADED PILES. DISCUSSION AND CLOSURE , 1994 .

[3]  Alexander M. Puzrin,et al.  Upper bound limit analysis of circular foundations on clay under general loading , 2003 .

[4]  John P. Carter,et al.  Contact between soil and circular foundations under eccentric loading , 2003 .

[5]  Alec Westley Skempton,et al.  The bearing capacity of clays , 1951 .

[6]  Guido Gottardi,et al.  A complete three-dimensional failure envelope for shallow footings on sand , 1994 .

[7]  E. Levin,et al.  Indentation pressure of a smooth circular punch , 1955 .

[8]  J. Carter,et al.  A failure surface for the bearing capacity of circular footings on saturated clays , 2002 .

[9]  Guy T. Houlsby,et al.  Combined loading of spudcan foundations on clay: numerical modelling , 2001 .

[10]  Susan Gourvenec,et al.  Effect of strength non-homogeneity on the shape of failure envelopes for combined loading of strip and circular foundations on clay , 2003 .

[11]  Finian Seng Chin Tan.  Centrifuge and theoretical modelling of conical footings on sand , 1990 .

[12]  Radoslaw L. Michalowski,et al.  Upper-bound load estimates on square and rectangular footings , 2001 .

[13]  Susan Gourvenec,et al.  Undrained Bearing Capacity of Square and Rectangular Footings , 2006 .

[14]  Rodrigo Salgado,et al.  Two- and three-dimensional bearing capacity of foundations in clay , 2004 .

[15]  Guido Gottardi,et al.  Standardized sign conventions and notation for generally loaded foundations , 1997 .

[16]  H. G. Hopkins,et al.  Axially symmetric plastic deformations in soils , 1961, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[17]  K. Terzaghi.  Theoretical Soil Mechanics , 1943 .

[18]  R. Nova,et al.  Settlements of shallow foundations on sand , 1991 .

[19]  Mark Randolph,et al.  Combined loading of skirted foundations , 1998 .

[20]  A. P. Green.  The plastic yielding of metal junctions due to combined shear and pressure , 1954 .

[21]  Susan Gourvenec.  Bearing capacity under combined loading - a study of the effect of shear strength heterogeneity , 2004 .