Experimental Study On The Mechanical Properties Of Self-Compacting Recycled Concrete-Filled Thin-Walled Steel Tube Columns

This paper presents self-compacting recycled concrete(SCRC) mix design, themechanical properties of SCRC, self-compacting recycled concrete-filled thin-walled steeltube(SCRCFTWST) short columns under axial compression and SCRCFTWST middle longcolumns under eccentric compression are tesed, main research contents and conclusions are asfollows:The mixture of C40SCRC was designed and its performances were tested, studies haveshown that:(1) C40SCRC can be prepared successfully by using recycled coarse aggregate;(2) the sand ratio of SCRC should be controlled between50%~55%, paste volume should beabout0.4m3/m3;(3) the cubic, prismatic compressive strength and elastic modulus of SCRCare lower than those of self-compacting normal concrete.SCRCFTWST short columns with different wall thickness and self-compacting normalconcrete-filled thin-walled steel tube(SCNCFTWST) short columns with different wallthickness were tested under axial compression, their load-displacement curves and load-straincurves were recorded, and their mechanical properties were compared. Test results show that:(1) the axial compression bearing capacity of SCRCFTWST short column is slightly lowerthan that of SCNCFTWST short column, while the ductility of the former is better;(2) thedispersion of mechanical properties of SCRC can be effectively reduced by thin-walled steeltube;(3)9codes of domestic and foreign are still aplicable in calculation of axial compressionbearing capacity of SCRCFTWST short column. The calculating results of CECS28:90arethe closest to test results, but its safety degree is the lowest.SCRCFTWST middle long columns with different wall thickness and SCNCFTWSTmiddle long columns with different wall thickness were tested under eccentric compression,their load-displacement curves, load-strain curves and load-lateral deflection curves wererecorded, and their mechanical properties were compared. Test results show that:(1) under thecondition of same wall thickness, axial compression and eccentric compression bearingcapacity of SCRCFTWST middle long column are slightly lower than those of SCNCFTWSTmiddle long column;(2) the load-lateral deflection curves of eccentric specimens arefundamentally symmetric and close to a sine curve;(3) the bearing capacity calculationmethods of6domestic and foreign codes about SCRCFTWST middle long column undereccentric compression are feasible. The calculation results of JCJ01-89are the closest to testresults, but its safety degree is the lowest.