Compressive behavior and design calculations of CFST slender columns with latticed annular steel part

In this paper, the design calculations of axially loaded CFST slender columns with latticed annular steel parts (SRCFST) are proposed based on the separated model. Finite Element (FE) analysis is conducted to predict the axial compressive performance of circular CFST slender columns with latticed annular steel parts. The test data are used to validate the FE model and to assess the suitability of design guidelines given in AISC 360–10, Eurocode 4, and DL/T 5629–2021. The validated FE model extensively analyzes the composite interaction between the concrete and the latticed annular steel parts as well as investigates the effect of different configurations of the latticed annular steel on compression performance. The influence of various parameters, including the constraint coefficient (ξ), steel reinforcement ratio (ρ), and slenderness ratio (λ), on the lateral confinement stress and ultimate bearing capacity of the latticed annular steel parts were assessed and quantified. Additionally, using the results of numerical simulations performed in this study, design procedures were proposed by modifying the separation model. The predictions from proposed design rules have demonstrated good agreement with the strengths of test and numerical specimens.