This article presents test results of a recent study on the axial compressive behaviour of fibre-reinforced polymer–confined compound concrete–filled thin steel tubes. The usage of compound concrete, which is a mixture of fresh concrete and large pieces of recycled concrete lumps, can recycle waste concrete in a simple but effective way. Totally, three series of tests were conducted, with the parameters including the relative strength between fresh concrete and recycled concrete lumps, the volumetric percentage (i.e. mix ratio) of recycled concrete lumps, the diameter-to-thickness ratio of the steel tubes, and the thickness of the fibre-reinforced polymer jackets being investigated. The stress–strain curves of the steel tube and compound concrete core were derived and the effects of different parameters were then examined and discussed. An existing stress–strain curve model of fibre-reinforced polymer–confined normal concrete-filled steel tubes was also found performing well in predicting the behaviour of fibre-reinforced polymer–confined compound concrete-filled steel tubes.
American Concrete Institute (ACI) (2008) ACI 318-08 Building Code Requirements for Structural Concrete (ACI 318-08) and Commentary. Farmington Hills, MI: ACI.
2.
ASTM D7565/D7565M (2010) Standard test method for determining tensile properties of fibre reinforced polymer matrix composites used for strengthening of civil structures.
3.
BS EN ISO 6892-1 (2009) Metallic materials. Tensile testing. Method of test at ambient temperature.
HeZJCaoWLZhangJX, et al. (2015) Multiaxial mechanical properties of plain recycled aggregate concrete. Magazine of Concrete Research67(8): 401–413.
6.
HuYMYuTTengJG (2011) FRP-confined circular concrete-filled thin steel tubes under axial compression. Journal of Composites for Construction, ASCE15(5): 850–860.
7.
JGJ/T 384 (2016) Technical Specification for Testing Concrete Strength with Drilled Core Method. Beijing: China Architecture & Building Press (in Chinese).
KhalafFMDeVennyAS (2004) Recycling of demolished masonry rubble as coarse aggregate in Concrete: review. Journal of Materials in Civil Engineering, ASCE16(4): 331–340.
10.
PoonCSShuiZHLamL (2004) Effect of microstructure of ITZ on compressive strength of concrete prepared with recycled aggregates. Construction and Building Materials18(6): 461–468.
11.
TengJZhaoJLYuT, et al. (2016) Behavior of FRP-confined compound concrete containing recycled concrete lumps. Journal of Composites for Construction, ASCE20(1): 04015038.
12.
TengJGHuYMYuT (2013) Stress–strain model for concrete in FRP-confined steel tubular columns. Engineering Structures49: 156–167.
13.
WangYLCaiGCLiYY, et al. (2019) Behavior of circular fiber-reinforced polymer-steel-confined concrete columns subjected to reversed cyclic loads: experimental studies and finite-element analysis. Journal of Structural Engineering, ASCE145(9): 04019085.
14.
WuBJinH (2019) Compressive fatigue behavior of compound concrete containing demolished concrete lumps. Construction and Building Materials210: 140–156.
15.
WuBJiMMZhaoXY (2016) State of the art of recycled mixed concrete (RMC) and composite structural members made of RMC. Engineering Mechanics33(1): 1–10 (in Chinese).
16.
WuBLiuCWuY (2014) Compressive behaviors of cylindrical concrete specimens made of demolished concrete blocks and fresh concrete. Construction and Building Materials53: 118–130.
17.
WuBLiuQXLiuW, et al. (2008) Primary study on recycled-concrete-segment filled steel tubular members. Earthquake Resistant Engineering and Retrofitting30(4): 120–124 (in Chinese).
18.
WuBPengCWZhaoXY, et al. (2018a) Axial loading tests of thin-walled circular steel tubes infilled with cast-in-place concrete and precast segments containing DCLs. Thin-Walled Structures127: 275–289.
19.
WuBYuYChenZ (2018b) Compressive behaviors of prisms made of demolished concrete lumps and fresh concrete. Applied Sciences-Basel8(5): 743.
20.
WuBYuYZhaoXY (2019) Residual mechanical properties of compound concrete containing demolished concrete lumps after exposure to high temperatures. Fire Safety Journal105: 62–78.
21.
WuBYuYChenZ, et al. (2018c) Shape effect on compressive mechanical properties of compound concrete containing demolished concrete lumps. Construction and Building Materials187: 50–64.
22.
WuBZhangSYangY (2015) Compressive behaviors of cubes and cylinders made of normal-strength demolished concrete blocks and high-strength fresh concrete. Construction and Building Materials78: 342–353.
23.
WuBZhaoXYZhangJS, et al. (2013) Cyclic testing of thin-walled circular steel tubular columns filled with demolished concrete blocks and fresh concrete. Thin-Walled Structures66: 50–61.
24.
XiaoJLiWFanY, et al. (2012) An overview of study on recycled aggregate concrete in China (1996–2011). Construction and Building Materials31: 364–383.
YuTHuYMTengJG (2014) FRP-confined circular concrete-filled steel tubular columns under cyclic axial compression. Journal of Constructional Steel Research94: 33–48.
27.
YuTZhaoHCRenT, et al. (2019) Novel hybrid FRP tubular columns with large deformation capacity: concept and behaviour. Composite Structures212: 500–512.
28.
ZhaoJLYuTTengJG (2015) Stress-strain behavior of FRP-confined recycled aggregate concrete. Journal of Composites for Construction, ASCE19(3): 04014054
29.
ZhaoXYWuBWangL (2016) Structural response of thin-walled circular steel tubular columns filled with demolished concrete lumps and fresh concrete. Construction and Building Materials129: 216–242.
