Evaluation of ultimate strength and plastic deformation capacity of steel pipe pile failed by local buckling at pile top in liquefied soil

This study investigates the buckling behavior of steel piles in liquefied soil, particularly addressing reduction in ultimate strength and plastic deformation capacity. During liquefaction, soil stiffness decreases considerably, shifting the inflection point of the piles downward and increasing the shear span ratio. This shift engenders reduction in the piles' structural capacity. Centrifuge tests were conducted to examine buckling failure at the pile top caused by local buckling under seismic loading conditions. Additionally, a static compression bending test was conducted to evaluate the piles’ ultimate strength and deformation capacity. Using test results, a finite element analysis (FEA) model was developed to simulate the phenomena observed in liquefied soil conditions. Parametric studies were then performed to evaluate the influences on pile performance of variables such as the generalized diameter-to-thickness ratio, axial force ratio, and shear span ratio. After proposing evaluation formulas for predicting the maximum strength and plastic deformation capacity, the authors validated them through comparisons with both experimentally obtained and FEA results. The findings contribute to better understanding and assessment of steel pile behavior in liquefied soils during earthquakes. • Centrifuge loading experiments are conducted on steel pipe piles in liquefied soil. • Local buckling behavior of piles during earthquakes is demonstrated. • FEA model is developed and used with experiments for parametric study. • The given formulas assess structural capacities of locally buckling steel pipe piles. • The proposed formulas are validated against experiment results.