Case study of the advanced octagonal cross-section self lifting hybrid tower buckling behavior

Abstract

The buckling behavior, as a key issue of the advanced self lifting steel–concrete hybrid tower, was analyzed in this paper. A simplified calculation method and an empirical formula were developed to estimate the critical buckling load of the tower structure. Both linear and nonlinear buckling analyses were performed for hybrid and reinforced concrete towers to identify their buckling modes, failure mechanisms, and weak sections. Case study results indicate that, in the steel–concrete composite system, the steel segment buckles before the concrete portion. For the concrete tower, the midsection (T3) exhibits earlier buckling than the bottom section, confirming T3 as the weak buckling zone. The linear buckling critical load was consistently higher than the nonlinear one, with nonlinear analysis providing results closer to realistic conditions. The geometric characteristics of the tower exert a strong influence on its buckling behavior: the critical buckling load increases nonlinearly with the base diameter (D) and wall thickness （t₂） , showing diminishing sensitivity at larger values, while it decreases sharply and nonlinearly with the height of the middle concrete section (H3), indicating a strong adverse effect of slenderness on structural stability. These case study may provide reference for optimizing the geometric design and stability assessment of hybrid wind turbine tower structures.