Structural Behavior of Hybrid FRP–Concrete–Steel Double-Skin Tubular Arches: Experiments and Numerical Modeling

Hybrid fiber-reinforced polymer (FRP)–concrete–steel double-skin tubular members (DSTMs) yield much higher strength-to-weight ratios and much better corrosion resistance than traditional reinforced concrete members. The steel tube and the FRP tube in DSTMs act as propping and formwork for concrete casting, thus significantly reducing construction efforts. DSTMs have been extensively studied as columns and beams. This paper presents a study aimed at understanding the benefit of using the double-skin tubular cross section in arches. Five double-skin tubular arches (DSTAs) with a span length of 3.6 m were fabricated and tested to investigate their behavior. The test program examined the effects of section load eccentricity, eccentricity of the steel tube position in the section, thickness of the FRP tube, and diameter of the steel tube on the behavior of the DSTAs. All the DSTA specimens displayed ductile behavior. The DSTAs were found to provide a significantly higher ultimate load than corresponding steel–concrete composite arches of a similar cross section. A higher cross-sectional load eccentricity was found to reduce the ultimate load of a DSTA. A numerical model was also developed in OpenSees (2019) version 3.2.2 to predict the behavior of the DSTAs. The numerical predictions were found to agree with the experimental results reasonably well.