Abstract
In this study, twenty-one recycled self-compacting concrete-filled circular steel tubular (RSCFCST) columns are designed and tested under eccentric compression. The studied parameters including the replacement ratio of the recycled coarse aggregate (RCA), strength grade of concrete, eccentricity, and length-diameter ratio L/D of specimens are considered. The load-stiffness curves of the specimens are obtained by observing the whole process of loading, and the effects of various parameters on the stiffness of the specimens are analyzed. Test results demonstrate that the RSCFCST short columns L/D≤4 under eccentric compression exhibit drum-like bending failures, while the RSCFCST long columns L/D>4 under eccentric compression experience the global flexural buckling failure modes. With the replacement ratio of RCA, the length-diameter ratio or eccentricity increases, and the bearing capacity of specimens under eccentric compression decreases. However, the increase in the strength grade of concrete increases the bearing capacity. The stiffness of the RSCFCST columns under eccentric compression gradually increases as the strength grade of concrete increases, while the eccentricity had an adverse effect on stiffness of specimen. With the increase of load, the increase of the length-diameter ratio would accelerate the stiffness degradation of specimen. The effect of the replacement ratio of RCA on stiffness of specimen in the elastic stage is not obvious. A validated FE model is employed to conduct parametric studies to widen the available test results. Additionally, an analytical model for predicting the effective stiffness of the RSCFCST columns under eccentric compression is proposed based on the moment magnifier method, and verification of this method is performed using the test data and FE analysis.
Highlights
With the rapid renewal and development of the city, a large amount of waste concrete is produced
D is the outer diameter of steel tube; t and L are the measured thickness and length of the steel tube, respectively; c is the replacement ratio of recycled coarse aggregate (RCA); e is the eccentricity of specimen; r is the radius of recycled self-compacting concrete (RSC); e/r is the eccentricity ratio; L/D is the length-diameter ratio of specimen; Nu is the ultimate load of the specimen
Experimental research and FE analysis on mechanical performance of recycled self-compacting concrete-filled circular steel tubular (RSCFCST) columns under eccentric compression are conducted in this study. e main conclusions are as follows: (1) e RSCFCST short columns under eccentric compression exhibit drum-like bending failures, while the RSCFCST long columns under eccentric compression experience the global exural buckling failure modes
Summary
With the rapid renewal and development of the city, a large amount of waste concrete is produced. Results revealed that the mechanical properties of recycled aggregate concrete making from these three treatment methods were significantly improved in quality compared with using the traditional methods. These studies confirm the feasibility and reasonability of recycled aggregates in engineering application. Mahgub et al [22] investigated the mechanical behavior of self-compacting concrete-filled elliptical steel tubular columns subjected to axial load. E results revealed that the mechanical behaviors of SCFST columns at high temperatures were similar to those of normal CFST columns, and the application of these columns in practical engineering buildings was feasible. Twenty-one RSCFCST columns under eccentric compression are tested to investigate the performance of stiffness
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