Post-local buckling failure of slender and over-design circular CFT columns with high-strength materials. (1st May 2020)

• Record Type: Journal Article
• Authors: Mou, Ben; Bai, Yongtao; Patel, Vipul
• Is Part Of: Engineering structures. Volume 210(2020)
• Publication Date: 2020-05-01
• Subjects: Seismic behavior -- Concrete filled steel tube -- High-strength materials -- Cyclic local buckling -- Fiber element modeling; Structural engineering -- Periodicals; Structural analysis (Engineering) -- Periodicals; Construction, Technique de la -- Périodiques; Génie parasismique -- Périodiques; Pression du vent -- Périodiques; Earthquake engineering; Structural engineering; Wind-pressure; Periodicals; 624.105
• DOI: 10.1016/j.engstruct.2020.110197
• Languages: English
• ISSNs: 0141-0296

Abstract

Highlights: High-strength materials are recommended to apply for seismic design of steel and CFT structures. Post-local buckling fracture is found in the experiments of slender circular CFT beam-columns. Thin-walled steel tubes with high-strength material enable to provide high confinement effect on concrete infill. D/t ratio and concrete/steel strength ratio play significant role in bending moment-axial force interaction behavior. Strength and stiffness degradation should be account in numerical modeling. Abstract: This paper investigates the ultimate behavior and post-local buckling failures of circular concrete-filled steel tubular (CFT) beam-columns under cyclic loading with constant axial force. The test specimens are fabricated by thin-walled steel tubes with 2 mm in thickness to clarify the main failure modes, and to evaluate the ultimate flexural behavior of slender and over-design circular CFT columns. Test results indicated that the column specimens with a large D/t ratio together with a thin-walled steel tube tend to trigger highly concentrated local buckling at column bottom where sequentially experienced low cycle fatigue fracture and the fragmentation of concrete infill. From the orthogonal analysis on the test results, it is found that the D/t ratio and concrete-to-steel strength ratio respectively play the most significant influences on the ultimate flexural strength and the critical axial load ratio. Finally, the fiber element model incorporating strength and stiffness degradation can accurately predict hysteresis behavior. This study provides fundamental supports for the design and analysis of thin-walled steel tubes to circular CFT columns with slender cross-section.