Revised Multilinear Regression Equations for Prediction of Lateral Spread Displacement

In 1992 and 1995, Bartlett and Youd introduced empirical equations for the prediction of lateral spread displacement; these equations have gained wide use in engineering practice. The equations were developed from the multilinear regression (MLR) of a large case history database. This study corrects and updates the original analysis. Corrections and modifications include: (1) Bartlett and Youd erroneously overestimated measured displacements for lateral spreads generated by the 1983 Nihonkai-Chubu, Japan earthquake; those errors are corrected herein. (2) Several sites were deleted where boundary shear impeded free lateral displacement. (3) Data were added from three additional earthquakes. (4) The functional form of the mean-grain-size term was modified from $\left({\mathrm{D50}}_{15}\right)$ to $\log ({\mathrm{D50}}_{15}+0.1\mathrm{mm})$ to produce improved prediction of displacements for coarse-grained granular sites. (5) The functional form of the model was changed from $\log \left(R\right)$ to $\log \left(R^{*}\right)\text{,}$ where $R^{*}$ is a function of the magnitude of the earthquake, to prevent unrealistic overprediction of displacements when R becomes small. The revised data were re-regressed to generate new MLR equations. The new equations are recommended for engineering practice.