A Review on the Torsional Behavior of Lightweight Concrete-Filled Steel Tubular Composite Members

Abstract

Based on prior published experimental, numerical, and analytical research, this review paper offers a thorough examination of the torsional behavior of lightweight concrete-filled steel tubular (CFST) composite elements. Using material properties, cross-sectional configuration, and interaction between steel and concrete components as key variables, this study aims to systematically evaluate the structural performance of composite systems under torsional loading. The available literature generally addresses three main aspects, including the behavior of hollow steel sections filled with lightweight concrete, the response of composite beams under combined bending and torsion, and the stress distribution as well as failure mechanisms under torsional loads. From reviewing these studies, it can be observed that the interaction between steel and concrete plays a significant role in improving the overall structural performance. Greater strength, tougher, ductile, and better able to eject energy are only a handful of ways this enhancement appears. In addition, the concrete core is mainly liable for transmitting compressive forces and enhancing stability, and the steel tube enclosing the object and aiding it in its ability to withstand tensile stresses. However, most previous studies have mainly focused on normal-weight concrete, with greater attention given to axial and flexural behavior. In contrast, pure torsional behavior has not been sufficiently investigated. Although lightweight concrete offers important advantages, such as reducing the self-weight of the structure and improving efficiency, its use in steel tube systems is still limited in the literature. Another point that can be noticed is the lack of experimental work compared to numerical studies. Because of this, researchers' analytical models tend to be less easy to verify. In addition, while there have been a few of studies examining into the ways that bending and torsion interact, very few have taken lightweight to account. composite elements filled with concrete. It is also clear that there is no unified design approach or well-established guidelines that specifically address torsional behavior in lightweight CFST members. Based on this, it can be said that the understanding of torsional performance in such systems is still incomplete. Therefore, further experimental and analytical investigations are required to develop more reliable prediction models and to improve design methods, especially for practical engineering applications that involve complex loading conditions.