Mechanical behaviors of steel reinforced ECC / concrete composite columns under combined vertical and horizontal loading

In order to improve the load capacity, seismic performance and performance-cost ratio of the columns, the concrete at the base of reinforced concrete （RC） columns is substituted with engineered cementitious composites （ECC） to form ECC/RC composite columns. Based on the existing material properties, the mechanical behaviors of the ECC columns, ECC/RC composite columns and RC columns were numerically studied under combined vertical and horizontal loading with the software of ATENA. Then, the failure mechanism of ECC columns and ECC/RC composite columns were comprehensively studied and compared with that of the RC columns. Then, the effects of the height of the ECC, the axial compression ratio, and the transverse reinforcement ratio on the mechanical behaviors of the composite or the ECC column are studied. The calculation results show that the ultimate load capacity, ductility and crack resistance of the ECC or ECC/RC composite columns are superior to those of the RC columns. The ECC/RC composite column with a height of the ECC layer of 1.2h （ h is the height of the cross section） can achieve similar mechanical properties of a full ECC column. With high shear strength, ECC can undertake the shear force and significantly reduce the amount of stirrups, avoiding construction issues and promoting its engineering application.