## 1 Introduction  
Round-ended concrete-filled steel tubular (RECFST) columns, as depicted in Figure 1, provide a unique amalgamation of benefits observed in rectangular and circular concrete-filled steel tubular (CFST) columns. These benefits encompass improved load-carrying capacity, ductility, and energy absorption. Notably, RECFST columns have been successfully employed as bridge piers in contemporary bridge projects, exemplified by their implementation in notable structures such as the Weihe Bridge and the Houhu Bridge in China [1]. The adoption of round-ended tube design in RECFST columns results in the efficient application of confining pressures on the concrete fill during axial compression, thereby enhancing the ductility and strength, in comparison with conventional reinforced concrete columns. In recent years, researchers have conducted comprehensive investigations, encompassing both experimental and numerical approaches, to investigate the performance of RECFST columns under various load conditions [2]. These studies have contributed valuable insights into the behavior of RECFST columns. For instance, [PERSON] et al. [3] and [PERSON] and [PERSON] [4] discussed the unique nature of the concrete confinement in RECFST columns, which lay between circular and rectangular CFST columns due to their distinctive shape. Extensive experiments were conducted by [PERSON] et al. [5] and [PERSON] et al. [6] to investigate the axial compressive behavior of RECFST stub columns. These studies meticulously analyzed the influence of key parameters, including the aspect ratio and steel stiffeners, on the strength characteristics of this composite column configuration. In addition, [PERSON] et al. [2,7] conducted systematic parametric analyses utilizing the ABAQUS solver. Their work focused on both stub and slender RECFST columns subjected to axial loading, leading to the establishment of innovative confinement effects and design methods. Furthermore, [PERSON] [8], [PERSON] et al. [9], and [PERSON] et al. [10] investigated the eccentric compressive performance of RECFST stub columns. By means of meticulous experimental investigations and diverse simulation techniques, such as finite element (FE) analysis and numerical fiber-based methodologies, researchers acquired comprehensive understanding of the nuanced behaviors exhibited by these columns when subjected to eccentric loads. The cumulative findings from these studies consistently highlighted the exceptional attributes of RECFST columns, encompassing remarkable strength, optimized structural characteristics, visually appealing architectural aesthetics, and minimal flow resistance coefficients. However, as marine construction progresses, many structures need to be built in highly corrosive environments, leading to an increased demand for high-quality building materials capable of withstanding harsh conditions. Traditional concrete structures are susceptible to corrosion and damage, making it imperative to explore more sustainable and durable alternatives. Some scholars have proposed the use of corrosion-resistant aluminum alloys as a substitute for ordinary carbon steel to promote the application of  
Figure 1: Cross-section structure of the specimen. concrete structures in marine engineering. Aluminum alloy, compared with carbon steel, possesses unique features such as an aesthetically pleasing appearance and lightweight properties. In recent investigations, [PERSON] et al. [11; 12; 13] conducted axial compression tests on concrete-filled square and circular aluminum alloy tubes, revealing that the full potential of square aluminum alloy tubes was not fully exploited. [PERSON] et al. [14] performed finite element analyses on concrete-filled aluminum alloy tubes subjected to axial compression. These studies [15; 16; 17] collectively demonstrated that concrete-filled aluminum alloy tubes effectively leveraged the advantages of both materials, resulting in improved axial compression capacity.