Diameter-dependent analytical p–y curves for response analysis of monopiles in sand

Abstract Large-diameter monopiles are extensively used to support onshore bridges, port terminals, and offshore wind farms due to their high load-bearing capacity, low settlement and excellent seismic performance. Meanwhile, the conventional p–y curves that are primarily derived from tests on small-diameter flexible piles, cannot capture the mechanical behavior of large-diameter rigid monopiles under complex dynamic loads. This study employs validated numerical simulations using OpenSees, calibrated against shaking table test results, to systematically investigate the lateral bearing characteristics of large diameter monopiles in sandy soils. The analysis highlights significant discrepancies in the initial stiffness, ultimate resistance, and displacement prediction when using conventional p–y curves. To address these limitations, a modified p–y curve formulation is proposed by introducing correction factors for initial stiffness ( $$\:\alpha\:$$ ), ultimate resistance ( $$\:\beta\:$$ ), and characteristic displacement ( $$\:\gamma\:$$ ), thereby refining the key parameters of the conventional p–y curve. The proposed model is validated through comparing its predictions with both physical and numerical experiments. The comparison demonstrated its accuracy in representing the pile-soil interaction behavior of large-diameter monopiles embedded in sandy sites.