Abstract:

In order to compare and analyze the degradation law of mechanical properties of three kinds of confined recycled concrete columns (spiral reinforced recycled concrete column, square steel tube recycled concrete column and circular steel tube recycled concrete column) after high-temperature water spraying cooling, 36 specimens were designed to carry out axial compression loading test after high-temperature water spraying cooling with section type, temperature and recycled coarse aggregate replacement rate as variable parameters. The whole failure process of the specimens was observed, and the differences of ultimate bearing capacity, initial axial compression stiffness and ductility of the three kinds of confined recycled concrete columns after high temperature water cooling were compared and analyzed. The results show that: with the increase of the maximum temperature, the ultimate bearing capacity, initial axial compression stiffness and ductility of recycled concrete columns with various constraints are degraded to varying degrees, and the degradation range of circular steel tube recycled concrete columns is the smallest and more stable. The ductility of recycled concrete-filled square steel tubular columns increases with the increase of temperature. With the increase of replacement rate of recycled coarse aggregate, the ultimate bearing capacity, initial axial compression stiffness and ductility of square steel tube and round steel tube specimens first decrease and then increase, and the fluctuation range is -15.3%~2.3%, while the influence of replacement rate on spiral reinforced concrete column specimens is relatively small, and the variation range is 0~12.9%.

Key words:  , recycled concrete, section form, high temperature, spray cooling, axial compression performance