Simplified analytical method for static and stability analysis of circular tapered friction piles

This paper presents a new, simplified analytical method to study the static and stability response of circular tapered friction piles in homogeneous or non-homogeneous Pasternak soil. The governing differential equation (GDE) of the proposed element is derived in a classical manner and solved using the Differential Transformation Method (DTM). This complex analysis is reduced to solve a system of two linear algebraic equations, which solution is readily available and easy to code. The proposed formulation is of practical interest for both onshore and offshore structures, and it can be used to conduct: (a) lateral load–deformation, (b) elastic stability, and (c) second-order analysis of prismatic and tapered friction piles. Tapered friction piles with various distributions of end-bearing resistance and skin friction can be investigated. The proposed formulation includes the effect of (i) any end-boundary condition at the ends of the element (i.e., translational and rotational constraints), (ii) a uniform or linear variation of skin friction, and (iii) a uniform or linear variation of the modulus of subgrade reaction. Five examples are presented to validate the accuracy of the proposed approach. • A new, simple approach to analyze tapered friction piles is proposed. • The effect of semirigid connections, friction, and soil non-homogeneity are included. • The Differential Transformation Method (DTM) is applied to solve the governing equation. • Lateral load–deformation, elastic stability, and second-order analyses can be conducted. • Purely end-bearing, partially frictional, and purely frictional piles can be analyzed.