Improving the deformation capacity of reinforced concrete columns under compressive load through the incorporation of glazed hollow Beads

Concrete mixed with glazed hollow beads (GC) is a lightweight aggregate concrete that combines reduced density with thermal insulation; however, the compressive behavior and deformation capacity of reinforced GC columns remain insufficiently quantified. In this study, axial and large-eccentric compression tests were conducted on eight reinforced concrete columns, including six GC columns and two normal concrete (NC) control columns. The test variables were concrete type, slenderness ratio (4, 8, and 10), and eccentricity (0 and 200 mm). The failure modes, load-deformation curves, lateral deformation, longitudinal reinforcement strain, and concrete strain were analyzed. The results show that GC columns cracked later and developed a wider damaged zone than NC columns, indicating improved deformation capacity. At a slenderness ratio of 8, the axial ultimate load of GC-8–0 was 4100 kN, which was close to that of NC-8–0 (4050 kN), whereas the large-eccentric ultimate load of GC-8–200 was 900 kN, 16.7% lower than that of NC-8–200 (1080 kN). As the slenderness ratio increased from 4 to 10, the ultimate load of GC columns decreased by 13.1% under axial compression and by 31.8% under large-eccentric compression, showing the stronger influence of second-order effects in slender GC columns. ANSYS finite element models provided acceptable agreement with the tests, with average simulated-to-test ultimate-load ratios of 0.90 for axial compression and 1.11 for large-eccentric compression. A design-oriented bearing-capacity calculation method was further proposed by introducing an equivalent stress coefficient for GC, and the experimental-to-predicted ratios were controlled within 1.25. The findings provide experimental and analytical evidence for using GC to improve the deformation capacity of reinforced concrete columns under compressive loading.