The moment response of rectangular piers was investigated numerically using a three-dimensional, non-linear finite element program, and by centrifuge modelling. In general numerical modelling behaviour matches observation well. Moment capacity increases almost linearly with pier length and simple expressions are derived. Dimensionless moment factors increase with soil packing but decrease significantly with pier length for aspect ratios less than 1.33. Prototype moment limits derived from the numerical and centrifuge studies compare reasonably well with predictions from the UIC/ORE and Broms design methods. (C) 2003 Elsevier Ltd. All rights reserved.