###### Abstract  
In order to promote the development of bridge assembly technology and accelerate the application of rectangular steel-tube-concrete composite truss bridges, this study focuses on the Yellow River Diversion Jiqing Main Canal Bridge as the engineering example and conducts a numerical analysis of a rectangular steel-tube-concrete composite truss bridge. Based on the results of the analysis, structural optimization is achieved in three dimensions--structural design, construction methods, and force analysis--leading to the establishment of key design parameters for throughput-type ultra-high-performance rectangular steel-tube-concrete composite truss bridges. The results show that filling the hollow sections with ultra-high-strength concrete can significantly enhance the load-bearing capacity. Additionally, employing prestressed concrete components addresses the bending and tensile load capacity challenges of composite structures, thus maximizing the material strength advantages. The proposed preliminary design scheme incorporates prestressed PBL-reinforced tie rods filled with ultra-high-performance concrete with optimal design parameters, such as high span ratios, wide span ratios, and ideal segment lengths, are suggested to ensure that the strength, stiffness, and stability comply with relevant standards. While ensuring that the structure meets safety, applicability, and durability criteria, the preliminary design scheme reduces steel usage by 23.5%, concrete usage by 11.6%, and overall costs by 17.29% compared to the original design. The proposed design demonstrates distinct advantages over the original in terms of mechanical performance, construction efficiency, economic viability, and durability, highlighting its promising application potential. b +
Footnote †: journal: Applied sciences  
performance, they are also linked to a high steel consumption, high costs, difficulties in transporting large, prefabricated steel segments, and complex construction processes. In contrast, concrete-filled steel tube structures exhibit significant advantages in terms of manufacturing, transportation, disaster prevention, construction, and environmental protection [3]. Constructing concrete-filled steel tube truss bridges can achieve the goal of rapid construction and address a series of issues arising from complex construction conditions. Consequently, steel-tube-concrete truss bridges have broad application prospects. Scholars have conducted a series of research studies on concrete-filled steel tube composite trusses and truss bridges. [PERSON] et al. [4; 5] conducted comparative experimental studies on truss specimens with and without concrete in the chords, indicating that filling the chords with concrete can improve chord stiffness, alter the failure mode of the joints, and enhance joint strength and stiffness. [PERSON] et al. [6] conducted experimental studies on empty steel tubes, concrete-filled steel tubes, and concrete-filled steel tube trusses with bridge decks, discovering that both filling the chords with concrete and adding bridge decks significantly affect the flexural behavior of the structure. They proposed simplified calculation formulas for flexural stiffness and strength. [PERSON] et al. [7] recommended that concrete-filled steel tube trusses should generally be constructed by first erecting steel tubes as the load-bearing framework and then filling them with concrete. However, concrete is susceptible to shrinkage, creep, and variations with temperature, which can lead to the bond stress at the steel-concrete interface being exceeded, thus leading, in turn, to debonding. [PERSON] et al. [8; 9; 10; 11], [PERSON] et al. [12], and [PERSON] et al. [13] proposed that segment prefabrication or setting studs or longitudinal stiffeners on the inner wall of chords can ensure bonding between the steel tubes and the concrete. [PERSON] et al.