## 1 Introduction
Through relevant retrieval, the number of publications on \"CFST\" in the last five years has reached more than 20,000, mainly focusing on the following aspects: (1) Changing section shape, such as circle, square, rectangle, oval, etc. [PERSON] carried out an experimental study on the compressive performance of oval CFST short columns [30]; [PERSON] et al. studied the hysteretic behavior of square CFST columns filled with high strength concrete under eccentric compression [31]. (2) CFST with a steel frame, with the steel frame comprising I-steel, T-steel, crisscross steel, etc. [PERSON] et al. conducted finite element analysis on the mechanical behavior of CFST columns with internal I-steel under axial and lateral cyclic loads [32]. (3) CFST with double-layer steel tubing, with the steel tubes being double-layered circular steel tubes, inner square steel tubes, outer circular steel tube, inner circular steel tubes, and outer square steel tubes. [PERSON] et al. carried out finite element analysis on CFST columns filled with concrete between double-layered circular steel tubes [33]; [PERSON] et al. carried out finite element analysis on the overall buckling performance of double-layered circular CFST long columns [34]; [PERSON] et al. carried out finite element analysis on the bearing capacity of CFST short column filled with concrete between double-layered circular steel tubes [35]. (4) Studies on CFST columns filled with high strength concrete. [PERSON] et al. carried out experimental research on circular CFST columns filled with high strength concrete [36]. (5) Connectors arranged on the inner surface of steel tubes to increase the interfacial strength between the steel tubes and the concrete. [PERSON] et al. conducted extensive studies on CFST columns with PBL connectors on the inner surface of steel tubes [37; 38]. (6) Thin-walled CFST. [PERSON] carried out an experimental study on CFST columns with low steel ratio [39]. (7) CFST columns with eccentric compression. [PERSON] carried out experimental research on CFST columns with eccentric compression [40]. Although the above studies on CFST are extensive and in-depth, no relevant studies and reports on CFST members filled with high titanium slag concrete have been conducted. High titanium slag is an industrial solid waste and the study on CFST columns filled with high titanium slag concrete is of great significance for the recycling and comprehensive utilization of solid waste. In Panzhihua and Xichang areas, CFST members filled with high titanium slag have been widely used in the columns of single-storey and multistorey industrial plants, equipment frame columns, various supports, trestle columns, subway station platform columns, power transmission and transformation poles, truss compression bars, piles, space structures, high-rise and super-high-rise buildings, and bridge structures, which have achieved good economic and social benefits. However, the design was mainly based on the theory of normal CFST, lacking theoretical basis and experimental proof. Therefore, the experimental study of CFST columns filled with high titanium slag concrete in this paper has practical significance.