Equivalent pile load-head settlement curve using a bi-directional pile load test

An equivalent pile load-head settlement curve to predict pile capacity has been obtained by using test results from the Osterberg Cell (O-cell). The method assumes that the pile is a rigid body and predicts very stiff pile behavior. This study describes a new method for predicting an equivalent pile load-head settlement curve considering the elastic shortening of piles. The static pile load test is compared to the O-cell test using two piles constructed 10 m apart (center-to-center distance). A measured O-cell test settlement consists of an elastic shortening under the load applied inside the pile and a net settlement. The measured net settlement is added to the elastic shortening, which has a different unit skin friction distribution under the top-down load on the pile head, to predict the equivalent pile load-head settlement curve. The new equivalent pile load-head settlement curve, considering the elastic shortening under top-down load, is similar to the pile load-head settlement curve obtained by the static pile load test before the pile yields. The new method can be used to effectively estimate the pile head settlement as well as pile capacity by using the bi-directional load test results.