Effects of segregation on reinforced concrete column, a numerical approach

Abstract

Abstract Columns are parts of building members that are exposure by the risk of segregation due to the elements’ dimension ratio, characteristic of concrete mix, and the concrete casting method. The segregation will create a higher density of coarse aggregate in lower part of the columns and result non-uniform distribution of concrete strength along the columns’ height. In previous research, the segregation on RC column were proven to decrease the performance of the member in withstanding the working load. As a result, the resulting ultimate load decreased up to 4% compared to the normal column. The segregation also decreases the level of ductility of the column, which was supported by the decrease of top drift on the segregated column. The researchers also found that segregation on RC column could change the failure mechanism from tension-controlled failure to compression-controlled failure. The failure on segregated column was initially begun by the crushing of concrete on the compression fibre and followed by the yield of tensile rebar. On the normal column, on the other hand, the failure on was initially begun by the yield of tensile rebar and followed by crushing of concrete on the compression fibre. In this paper, researchers would like to investigate the behaviour of segregated RC column using numerical approach. The results showed that (1) the segregated column creates a linear drift pattern, while the normal column shows a graph with double curvatures at the ultimate condition; (2) the resulting stress contour showed a similar pattern in the segregated column and in the normal column, while the normal column could withstand working stress up to 25% higher than the segregated model; and (3) column drift from numerical analysis is more reliable than the experimental works as the experimental data only provided the reading of drift at two level of column height.