Compressive behaviour of engineered cementitious composites and concrete encased steel composite columns

This paper presents the results of an experimental study on the compressive behaviour of engineered cementitious composites and concrete encased steel (ECC-CES) composite columns. Two configurations of ECC-CES composite columns based on fully and partially concrete encasement were considered. A total of eleven short columns with different ECC and concrete encasing configurations were tested under pure compression. The effects of ECC strength, concrete strength and column configuration on the column compressive behaviour were investigated and reported in terms of failure modes, load-deformation curves, ductility and toughness. In addition, in order to study the confinement effect of different thickness ECC covers on high strength concrete (HSC), three ECC encased HSC short columns without encased steel section were also tested. The experimental results were compared with the ultimate strength predictions from different design codes for the tested columns. It was found that current design guidelines were generally conservative. Therefore, new equations with modified factors to predict the ultimate strength of ECC-CES columns were proposed. Finally, a comparison of performance of ECC-CES with conventional CES columns suggested that the ECC encasement could provide an alternative way to confine concrete core in columns applications.