Fire Behavior of Axially Loaded Circular Concrete-Filled Double-Skin Tubular Columns: Investigating the Role of PVC as an Alternative Inner Tube Material

Abstract

This research provides a comprehensive investigation of the fire behavior of axially loaded circular concrete-filled double-skin tubular (CFDST) columns under high-temperature conditions. The study primarily focuses on the feasibility of using PVC pipes as an alternative material for the inner tube. Through a series of experimental investigations, this study evaluates the axial load capacity of CFDST columns, analyzing key parameters such as outer tube slenderness, outer-to-inner tube dimension ratio, and inner tube material type. A comparative analysis is conducted between the experimental results and established design equations from AISC, Han, and the Eurocode to assess their accuracy in predicting the strength of composite-filled square pipe tubular (CFSPT) and CFDST columns. The findings indicate that while the use of PVC pipes results in a slight reduction in column strength, it does not significantly affect the strength index or concrete contribution ratio. Moreover, despite being a cost-effective alternative, PVC-based CFSPT columns demonstrate comparable performance to traditional CFDST columns. This research contributes valuable insights into the potential for integrating sustainable and economical materials like PVC in structural engineering applications, particularly in fire-prone environments. Additionally, it opens new avenues for future research, particularly in understanding the long-term behavior and fire resistance of alternative construction materials.