Experimental behaviour of recycled aggregate concrete filled stainless steel tube stub columns and beams

The behaviour of recycled aggregate concrete (RAC) filled stainless steel tube (RACFSST) stub columns and beams under short-term loadings was experimentally studied, and a total of 28 specimens, including 14 stub columns and 14 beams, were tested. The experimental investigations were carried out on circular and square specimens with recycled aggregate replacement ratio of 0, 25%, 50% and 75%, and both recycled coarse aggregate (RCA) and recycled fine aggregate (RFA) were adopted in the tests. The main objectives of these tests were threefold: first, to describe a series of tests on new composite stub columns and beams; second, to investigate the effect of cross-section type and recycled aggregate replacement ratio on the compressive and flexural behaviour of RACFSST specimens; and finally, to evaluate the accuracy of the calculated bearing capacity, bending moment capacity and section flexural stiffness of the RACFSST specimens by using the design formulae in six codes related to the design of concrete filled carbon steel tube. The experimental results showed that the RACFSST stub columns and beams under short-term loadings had the stable load versus deformation responses and the good deformation-resistant ability, and the performance of core RAC was generally enhanced due to the confinement of the outer stainless steel tube.

► RACFSST stub columns and beams.
► Compressive and flexural behaviour of RACFSST specimens.
► Calculation for the bearing capacity, bending moment capacity and section flexural stiffness of RACFSST specimens using the existing design codes.