Experimental study on the eccentric compressive behavior of steel reinforced concrete composite columns with stay-in-place ECC jacket

Abstract

Steel Reinforced Concrete (SRC) column with stay-in-place ECC jacket is a novel type of composite columns synergizing the merits of advanced construction materials and precast technologies. This study experimentally investigates the eccentric compressive behavior of ECC-SRC columns. The optimal fiber content and mix proportion desirable for jacket were determined prior to the specimen fabrication. The test variables include the load eccentricity, ECC jacket thickness, presence of stirrups and the jacket surface treatment. In addition, two conventional SRC columns were also tested as control specimens. The test results in terms of failure mode, deformation response, flexural stiffness, load-carrying capacity, post-peak ductility and residual capacity were evaluated in detail, and Digital Image Correction (DIC) technique was also employed for better visualization of crack distribution and strain field. Based on the test results, the interaction between profiled steel, infilled concrete and the ECC jacket was analyzed to uncover the load-carrying mechanism of ECC-SRC columns. Finally, the axial force-bending moment (N-M) interaction diagrams constructed by current design code EN 1994-1-1 are compared with tested capacity, based on which design recommendation was proposed to facilitate the design and application of ECC-SRC columns.