Davisson's method (Offset Limit Method) is probably the best-known and most widely used method for predicting the ultimate pile load from load test results. This method when applied to the load-settlement curve of a tested pile, usually fails, unless the pile is loaded close to failure. Results of eighty static axial load tests on different types of piles carried out in Egypt were analyzed according to Davisson's method to obtain the ultimate load. Only four out of the eighty tests satisfied the method and predicted the ultimate load.

Elastic and plastic settlements were measured for each pile load test at test load. These values were compared with those obtained from their relevant parts in Davisson's equation. Davisson's equation, when applied at test load equal to either one and a half or twice the working load, gives values higher than those measured for both the elastic and plastic parts.

Davisson's equation was modified to accommodate the difference between the calculated and the measured values at the test load. The suggested form of Davisson's equation allows the prediction of the pile ultimate load using the pile test load without having to extrapolate the load-settlement curve.