Eccentric compression behaviour of precast H-shaped steel support in foundation pit engineering

Abstract

To clarify the key performance of precast H-shaped steel support structures and promote the development of green, low-carbon foundation pit support systems, compression tests were conducted on recyclable and reusable H-shaped steel support single-leg specimens, including two concentrically-loaded specimens and two eccentrically-loaded specimens. A reliable finite element analysis model was established for parametric analysis. The failure modes, load-displacement curves, deflection curves, and strain responses of the specimens were analysed based on experimental and finite element analysis results. The results indicated that the failure modes of the specimens under both axial and eccentric compression were similar, with increased lateral deformation leading to overall instability. Local buckling occurred at the outer H-shaped steel flange of the spliced node. The outermost bolts of the cover plate and the end plate bolts were at risk of breaking, when the support segment became unstable. Eccentrically-loaded specimens with a 50-mm eccentricity exhibited lower ultimate strength and higher out-of-plane deformation compared to concentrically-loaded specimens. Considering the major-axis eccentricity, the critical stable load decreased by 14.74 % and the out-of-plane deformation increased by 40.58 %. Considering the minor-axis eccentricity, these values were 48.84 % and 340.71 %, respectively. The parametric analysis also revealed that the length, section size, and eccentricity were the primary factors affecting the stiffness and ultimate strength of the support segments. The interaction equations for flexure and compression in the developed codes were applicable to support segments, and Eurocode 3 was more suitable than AISC360 and GB50017–2017.