Innovative development and structural behavior of hollow columns using inflatable molds

Abstract This study introduces a novel approach for constructing hollow columns using precast (PC) methods enhanced by inflatable air tubes as internal molds. The proposed method addresses practical challenges in conventional hollow column construction, such as limited constructability, high production cost, and interference between internal molds and transverse reinforcement. By employing inflatable air tubes, the method simplifies reinforcement assembly and formwork, overcoming key difficulties associated with PC hollow column fabrication. Additionally, an innovative arrangement of transverse reinforcements specifically designed for hollow columns effectively overcomes interference issues, further streamlining construction while preserving structural integrity. The practicality of the method was validated through tests on PC hollow columns and HPC (half‐precast concrete) columns with onsite concrete filling. These tests showed that despite reductions of 30% in concrete volume the hollow columns maintained structural behavior comparable to that of solid columns in terms of bending and axial strength. This study lays the groundwork for the development of more cost‐effective and efficient construction methodologies using PC hollow columns, based on experimentally validated performance.