Behaviors of steel-reinforced ECC columns under eccentric compression

Engineered cementitious composite (ECC) is a type of high-performance composite with pseudo strain hardening behavior and multiple cracking properties. The cracking and durability problems induced by concrete brittleness can be effectively avoided by substituting concrete with ECC. In this study, a total of eight steel-reinforced columns with various longitudinal reinforcement ratios and load eccentricities were tested under eccentric compression. It was determined from the test results that steel-reinforced ECC (R/ECC) columns exhibit superior performance to reinforced concrete (RC) columns in terms of load-carrying capacity, ductility, crack control ability, and damage tolerance. All columns finally failed in matrix crushing; however, the failure patterns of R/ECC columns are extremely different from those of RC columns. Significant concrete spalling occurred in the RC columns, while no sign of ECC spalling was observed in the R/ECC columns, owing to the fiber bridging effect of ECC. In addition to experimental work, a theoretical model was proposed to predict the moment-curvature response of the R/ECC column. The prediction results are in strong agreement with test data. Furthermore, parametric studies were conducted to illustrate the effects of matrix types, longitudinal reinforcement ratio, ECC compressive strength, and ECC tensile ductility on the moment-load interaction curves of columns.