Experimental Study on the Behavior of Recycled Concrete-Filled Thin-Wall Steel Tube Columns Under Axial Compression

Behavior of CFRP-confined reactive powder concrete-filled steel tubes under axial compression

“…According to the Ding et al (2018), the strength of concrete confined by steel tubes is C50. When the confinement between the steel tube and concrete took effect, the strain ratio exceeded 0.5, which was higher than the strain ratio range of 0.295∼0.4; this indicated that less confinement occurred in the case of RPC confined by steel tubes than in that of ordinary concrete confined by steel tubes, and also suggested that the lateral expansion of RPC in confined concrete is less complete than that of ordinary concrete (Wu and Lin, 2005).…”

“…The second was the elastic-plastic stage. Compared to ordinary concrete, the strain of the RPC still varied linearly due to the linearity of the increase in unconfined RPC stress-strain (Wu and Lin, 2005), while the steel tube had entered an elastic-plastic state. Therefore, the internal force was redistributed between the steel tube and the RPC was caused, resulting in progressive non-linearity of the curves.…”

“…Compared to traditional metal or concrete structures, the use of RPCFSTs (where the RPCFSTs discussed below do not contain steel fibers) in columns can reduce the cross-sectional size of the column and ultimately increase the usable area of the building (Wu and Lin, 2005). Therefore, RPCFST columns can provide superior vertical components for large-span, high-rise, and tower buildings and other heavy-duty engineering construction projects (Rong et al, 2018).…”

“…Therefore, RPCFST columns can provide superior vertical components for large-span, high-rise, and tower buildings and other heavy-duty engineering construction projects (Rong et al, 2018). Most studies have focused on the axial compression behavior of RPCFSTs (Lin et al,2005; Luo et al, 2017; Wu and Lin, 2005; Yan et al, 2011). According to these studies, the axial compression properties of these composite members are better than those of steel or concrete structures, because the steel tube restricts the core RPC while the RPC delays local buckling of the steel tube.…”

“…According to these studies, the axial compression properties of these composite members are better than those of steel or concrete structures, because the steel tube restricts the core RPC while the RPC delays local buckling of the steel tube. However, we can see from these studies (Lin et al,2005; Luo et al, 2017; Wu and Lin, 2005; Yan et al, 2011) that the predominant failure mode of these composite members is external local buckling of the steel tubes, which decreases the strength and ductility of the members, leading to excessive inelastic deformation. Although high-tensile and thick-walled steel tubes can be used to confine the core RPC and thus alleviate defects due to local buckling, this will increase steel consumption, leading to relatively high structural weight and costs.…”