Local instability and interactive mechanism analysis of UHTCC-encased rectangular steel tubular columns

Abstract

In recent years, the ultra-high toughness cementitious composite (UHTCC) has become a focal point of research owing to its exceptional crack resistance and excellent ductility. These characteristics are particularly beneficial for preventing corrosion resulting from the penetration of chloride ions and water. Building on these advantageous properties, this study introduces a novel UHTCC-encased steel tubular (UEST) column, employing UHTCC as an outer cladding for the hollow steel tube, to achieve both lightweight construction and improved durability. A theoretical model was developed to investigate the local instability of the UEST columns, and the axial resistance of UEST columns can be predicted using the proposed model. Subsequently, finite element (FE) models of UEST columns, equipped with studs or perfobond strips (PBL), were established and validated against the existing experimental data. Additionally, the interactive mechanism of each component (steel and UHTCC layer) of UEST columns was comprehensively investigated using the FE model. The theoretical model achieved high accuracy in predicting the axial resistance of UEST columns with both thick and thin-walled steel tubes, resulting in an average error of 2.4 %. Finally, some practical design recommendations for UEST columns were derived from the theoretical model.