A p-y Model for Large Diameter Monopiles in Sands Subjected to Lateral Loading under Static and Long-Term Cyclic Conditions

The design of large diameter monopiles subjected to cyclic lateral loading is of interest in many applications, such as, for example, in the offshore wind energy industry. Engineering design methods to estimate the deflection of these structures are required for this purpose. In the present work, a p-y model for large diameter monopiles subjected to lateral loading is proposed. The model considers a pile in cohesionless soil subjected to static and long-term cyclic loading. Its formulation features the consideration of nonlinear relations for the ultimate soil resistance pu and the initial subgrade modulus Epy0 among the soil depth and a cyclic factor that accounts for the effect of the soil density and loading amplitude. A relation is also proposed to account for a base shear force at the tip of the monopile. The proposed relations were employed and solved under the beam on nonlinear Winkler foundation (BNWF) approach and were adjusted to simulate a number of three-dimensional (3D) finite-element (FE) models accurately, accounting for variations on pile geometry, soil properties, and loading conditions. In the end, the performance of the proposed relations was evaluated through the comparison with a field test and a centrifuge test. (c) 2020 American Society of Civil Engineers.

Automated summary

This study proposed a p-y model for large diameter monopiles subjected to lateral loading, considering the pile in non-cohesive soil under static and long-term cyclic loading. Nonlinear relations and cyclic factors were used to simulate the ultimate soil resistance and initial subgrade modulus accurately. The proposed relations were adjusted to accurately model variations in pile geometry, soil properties, and loading conditions through 3D finite element models.