Real-scale tests on bundle-bar-filled circular hollow sections (BBFC) under eccentric compression

The escalating demand for innovative, multifunctional, and advanced composite structures stems from the pressing concerns related to cost efficiency and environmental impact, alongside interest in the prefabrication methods within the construction industry. This paper advances a pioneering approach by proposing the utilization of high-strength bundle-bar-filled circular hollow sections (BBFC) as columns. In this method, a bundle comprising high-strength reinforcing bars with an impressive yield strength of 670 N/mm² is strategically placed within a steel tube, varying in related-slenderness values from 0.86 to 2.44. Subsequent to this arrangement, the bundle undergoes grouting with mortar, resulting in the formation of the BBFCs. The composition of the bundle is a critical aspect, with different configurations featuring 1, 3, 7, and 19 high-strength bars. Given the intricacies involved in the fabrication process, this paper meticulously outlines the unique techniques employed to successfully manufacture the BBFCs. To comprehensively evaluate the performance of these innovative columns, a series of ten real-scale tests were conducted. These tests look at various aspects, including capacity, flexural stiffness, deflection, and strain response. In addition to experimental validation, finite element analysis was applied, not only to corroborate the empirical findings but also to lay the foundation for future parametric studies. These subsequent investigations aim to explore and understand the influence of different geometric and material features on the structural behaviour of this innovative composite column, thereby contributing to the advancement of knowledge in the field. • This study unveils state-of-the-art composite column design and their test results. • Bundle-bar columns offer cost-efficiency and structural robustness. • Bundle-bar columns are recommended for mid- to high-rise buildings. • The study highlights the importance of deflection control measures. • Promising structural and economic advantages pave the way for future design.