Abstract: “The main object of this paper is to fit with high degree of accuracy the true structure response by considering the concept of interface element which is used to simulate three dimensional soil-structure interaction in the dynamic analysis, therefore the dolphin of khor Al-Amaya berth no. 8 is analyzed as a case study. The (p-y), (t-z), and (q-z) curves which are adopted by American Petroleum Institute (API) are used to find normal and tangential interface moduli and end bearing modulus. For this purpose, a computer Fortran program Offshore_Inter has been built to obtain the required solution. The subspace iteration method is used to find the free vibration solution while Newton-Raphson modified method combined with Newmark’s method is applied to get the nonlinear forced vibration solution. For both solutions, the conjugate gradient algorithm is used as a solver of the dynamic problem. A parametric study has been carried out including different soil type, soil engineering properties, l”

Keywords: merican Petroleum Institute API, Newmark’s method, Conjugate gradient algorithm, Reese solution, Winkler method, Pile response