Stiffness Analysis of Recycled Self-Compacting Concrete-Filled Circular Steel Tubular Columns under Eccentric Compression

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-diameterratio (L/D) o fspecimensareconsidered.Theload-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 RSCFCSTshort 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 there place mentratioofRCA,the length diameter ratiooreccentricity 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 concretei ncreases, while the eccentricity had an adverse effect on stiffness of specimen.With the increase of load, thei ncrease of the length-diameter ratio would accelerate the stiffness degradation of specimen.The effect of the replace mentratio of RCA on stiffness of specimen in the elastic stage is not obvious. Avalidated FE model is employed to conduct parametric studies to widen the available test results.A dditionally, ananalytical model for predicting the effective stiffnessof the RSCFCSTcolumns 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.