Load-Bearing Performance of Segmental Prestressed Concrete-Filled Steel Tube Chords in Lattice Wind Turbine Towers

To address the combined demands of lightweighting, modular construction, and durability in ultra-tall wind-turbine towers, a segmental prestressed concrete-filled steel-tube (PCFST) chord for lattice towers is investigated in this study. A finite-element approach is validated against published tests on CFST columns, showing close agreement in load–displacement response and failure modes. Based on this validation, a finite-element model of the segmental PCFST chord is developed to clarify load-bearing mechanisms and parameters under axial compression and tension. The results show that, in compression, the concrete core governs the response; after steel yielding, the tube undergoes multiaxial stress redistribution—rising hoop stress and falling axial stress—consistent with von Mises yielding and dilation of confined concrete. In tension, load sharing is dominated by the steel tube and tendons, with limited concrete contribution. Parametric analyses indicate that end stiffeners markedly improve tensile behavior: with eight stiffeners, initial stiffness and peak tensile load increase by 1.8 times and 1.3 times relative to no stiffener, while effects in compression are minor. Increasing initial prestress improves tensile performance but shows diminishing returns beyond a moderate level and reduces compressive yield capacity. Increasing flange thickness enhances tensile performance with negligible compressive effect, whereas greater tube thickness increases both capacities and the initial stiffness.