Behavior of Steel-jacket Retrofitted Column with Recycled Aggregate Concrete under Eccentric Loading

Abstract

In order to achieve the goal of green building, the idea of steel-jacket retrofitted RC columns with recycled aggregate concrete was proposed. Tests of 1 original column, 3 retrofitted columns under axial compressive loading and 8 retrofitted columns under eccentric loading were conducted. It is found that after retrofitted by steel-jacket and recycled aggregate concrete, the bearing capacity and deformation performance of the RC column are significantly improved, where the relative bearing capacity is increased by 1.12 times on the average. The effect of recycled coarse aggregate replacement ratio on eccentric bearing capacity is not obvious, while the mid-span strain of steel-jacket increases slightly when the replacement ratio grows under large eccentricity. The peak loads of the retrofitted column with preload appear earlier, which shows a negative effect on deformation performance. Besides, the influence of the eccentricity is similar to that of the concrete-filled steel tubular column: as the eccentricity increases, the bearing capacity decreases and the compression-side strain of steel-jacket increases, and this trend becomes stronger when the replacement ratio increases. Finally, according to the comparison of design codes and the researches, eccentric bearing capacity calculated by EC4 is most consistent with the test results for this kind of retrofitted columns.

Keywords: steel jacket,  recycled aggregate concrete,  strengthening,  eccentric compression test