Performance of fly ash and silica fume self-compacting concrete filled steel tube stub columns under axial compression

Abstract

Experimental research on the performance of fly ash and silica fume selfcompacting concrete filled steel tube (FSS CFST) stub columns under axial compression were conducted. The main parameters varied in the tests are steel tube’s diameter to thickness ratio, D/t (from 20 to 33), and yield strength (from 275.83 MPa to 350.51 MPa). The self-compacting concrete grade used as infill is M60 concrete with 50% and 10% addition of fly ash and silica fume, as partial replacement of Portland cement. The performance of FSS CFST stub columns is examined via the axial compression capacity, load-shortening response, and mode of failure of 12 specimens. The results indicate that the ultimate axial load capacity of the columns increases as the D/t ratio decreases. The FSS CFST columns have a maximum concrete contribution ratio of 3.72, a strength index greater than unity, and a ductility index of 2.431 and below. The predicted values obtained using Eurocode 4 closely estimate the test results with a mean of 0.927 and a standard deviation of 0.073. Conversely, the predicted values using ACI code are more conservative with a mean of 1.341 and a standard deviation of 0.089.