TY - JOUR
T1 - Experimental investigation and strength prediction of concrete-encased square CFST structures under axial tension
AU - Ma, Dan Yang
AU - Lin, Guang Ting
AU - Han, Lin Hai
N1 - Publisher Copyright:
© 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
PY - 2026/12/1
Y1 - 2026/12/1
N2 - Concrete-encased concrete-filled steel tubular (CFST) structures consist of an inner CFST component and an outer reinforced concrete (RC) component. Although their compressive behaviour has been extensively studied, the axial tensile behaviour of concrete-encased square CFST structures remains insufficiently understood, particularly regarding failure mode, hybrid effects, and strength prediction. This study experimentally investigates the axial tensile behaviour of this hybrid structure and develops an improved strength prediction method. Twelve specimens were tested under monotonic axial tension, including eight concrete-encased square CFST specimens, one concrete-encased circular CFST specimen, two square CFST specimens, and one RC specimen. The effects of steel tube strength, steel tube thickness, fabrication process and cross-sectional configuration were examined. Two typical failure modes were identified according to crack distribution: the uniform cracking mode and the end cracking mode. The uniform cracking mode allowed more distributed strain development and greater participation of the outer RC component, whereas the end cracking mode was associated with localized end damage and premature fracture of rebars. Increasing the steel ratio significantly improved tensile strength and deformation capacity, while simply increasing the steel tube strength did not lead to a proportional improvement in tensile strength. The effects of fabrication process and cross-sectional configuration were reflected mainly in the strain distribution and failure localization. Based on the observed load-transfer mechanisms, an improved strength prediction method was proposed by considering the biaxial stress enhancement of the steel tube, limited utilization of high-strength steel, and different RC contributions in the two failure modes. The proposed method showed improved accuracy and lower dispersion for this type of hybrid structure.
AB - Concrete-encased concrete-filled steel tubular (CFST) structures consist of an inner CFST component and an outer reinforced concrete (RC) component. Although their compressive behaviour has been extensively studied, the axial tensile behaviour of concrete-encased square CFST structures remains insufficiently understood, particularly regarding failure mode, hybrid effects, and strength prediction. This study experimentally investigates the axial tensile behaviour of this hybrid structure and develops an improved strength prediction method. Twelve specimens were tested under monotonic axial tension, including eight concrete-encased square CFST specimens, one concrete-encased circular CFST specimen, two square CFST specimens, and one RC specimen. The effects of steel tube strength, steel tube thickness, fabrication process and cross-sectional configuration were examined. Two typical failure modes were identified according to crack distribution: the uniform cracking mode and the end cracking mode. The uniform cracking mode allowed more distributed strain development and greater participation of the outer RC component, whereas the end cracking mode was associated with localized end damage and premature fracture of rebars. Increasing the steel ratio significantly improved tensile strength and deformation capacity, while simply increasing the steel tube strength did not lead to a proportional improvement in tensile strength. The effects of fabrication process and cross-sectional configuration were reflected mainly in the strain distribution and failure localization. Based on the observed load-transfer mechanisms, an improved strength prediction method was proposed by considering the biaxial stress enhancement of the steel tube, limited utilization of high-strength steel, and different RC contributions in the two failure modes. The proposed method showed improved accuracy and lower dispersion for this type of hybrid structure.
KW - Axial tension
KW - CFST
KW - Concrete-encased CFST structure
KW - Failure mode
KW - Square steel tube
KW - Strength prediction
UR - https://www.scopus.com/pages/publications/105049737413
U2 - 10.1016/j.engstruct.2026.123710
DO - 10.1016/j.engstruct.2026.123710
M3 - 文章
AN - SCOPUS:105049737413
SN - 0141-0296
VL - 368
JO - Engineering Structures
JF - Engineering Structures
M1 - 123710
ER -