estimation of hydrodynamic forces on the cylinderical smooth piles to random waves and currents

most codes such as api and bsi recommend morison’s equation to estimate hydrodynamic forces on offshore structures. significant differences exist among these codes due to using different methods of analysis and estimation of force coefficients. in this paper, data from full scale tests have been used to evaluate random waves and uniform current actions on the smooth piles. four time and frequency domain analysis methods were used to estimate cd & cm. force time series fitting method (ls-ts) has given better results than the others. furthermore, the errors from estimating hydrodynamic forces on smooth piles are more than those on rough piles.