Experimental investigation of bond-slip stress of cold-formed CFSTs stub-columns in a post fire based on four cycles push out tests. (June 2022)

• Record Type: Journal Article
• Authors: Naghipour, Morteza; Pourniazi, Nima; Hasani, Seyed Mohammad Reza
• Is Part Of: Structures. Volume 40(2022)
• Page Start: 977
• Page End: 990
• Publication Date: 2022-06
• Subjects: Concrete-filled steel tubes (CFST) -- Square sections -- Stripe studs -- Bond stress -- High temperature; Structural engineering -- Periodicals; 624.1
• DOI: 10.1016/j.istruc.2022.04.073
• Languages: English
• ISSNs: 2352-0124

Abstract

Abstract: Concrete-filled steel tube (CFST) columns display a fine fire resistance. In the following research the performance of shear studs and their connection configuration in square concrete-filled steel tube stub-columns were investigated. The dimensions of the hollow square sections were 100x100 mm 2 with a wall thickness of 4 mm. Shear studs including inward-bent studs welded from the back, inward-bent studs welded from inside and bolts which are stiffening elements were put in place and the tubes were filled with concrete and then placed in the furnace for 60 min under 20 °C, 250 °C, 500 °C and 750 °C. The columns were then loaded after cooling down to the room temperature. Moreover one tube without shear studs was tested as control specimen. In this research the effect of increasing temperature and cooling or post-fire behavior on bond stress and slip between concrete core and inner steel tube were investigated. A total of 16 specimens were tested for achieving this goal. According to the results the use of strip shear studs have a significant effect on increasing the lateral stiffness, axial compressive strength and bond stress of the column. Furthermore until 500 °C the bond between concrete and steel was weakened. But in the temperatures of 500 °C and 750 °C due to Poisson effect in concrete and increased volume regarding micro-cracks, the friction between steel and concrete is increased and the loading capacity of the cross section is enhanced consequently.