This research work focuses on determining the internal force distribution in piles from displacement measurements when the piles no longer behave fully elastically. The method is based on the principle of virtual work (unit-load method) and allows the calculation of the bending moment distribution along piles, which is assumed to be the dominant internal force in bending. Four recent case studies were used, focusing either on liquefaction induced loading or on static induced plasticity. Comparison between the observed and calculated bending moments highlighted the method’s flexibility to derive accurate results in various soil conditions, length-size of experiment and load conditions. The method is also equally applicable to piles and to retaining walls. The maximum error between observed and calculated maximum bending moment ranged from 30% to less than 5% whereas the location of the maximum bending moment along the length of the pile was successfully calculated in all tests which stands promising for prediction of plastic hinges. The method can be used as a reliable-rapid tool to estimate the pile state following earthquake loading. This, in turn, can be used as a resilient and vulnerability indicator of the pile ability to resist further loading and continue to perform its function safely
