Strengthening of structurally deficient and partially damaged short square columns using GFRECC retrofit technique

Glass fiber-reinforced engineered cementitious composite (GFRECC) is being used in this study to repair short square reinforced concrete columns that are structurally weak and measure 100 mm × 100 mm × 1000 mm. Polypropylene fibers and E-glass rovings are combined in a cementitious matrix to create the composite. Eight columns were cast and tested: two low-strength concrete columns (E-A4), two standard control columns (E-A1), two with inadequate main reinforcement (E-A2), and two with insufficient lateral ties (E-A3). The GFRECC technology was used to repair and retrofit all specimens after they had been preloaded axially until the first obvious cracks appeared. With ANSYS 14.0, corresponding numerical models (N-A1, N-A2S, N-A3S, and N-A4S) were created and examined. To evaluate the restoration of ultimate load capacity, stiffness, energy absorption, and ductility, a parametric study was carried out. Retrofitting has enhanced the ultimate load for E-A2S and E-A3S columns. The increment was noticed as 2.36 and 2.52 times the value for the E-A1 column. A similar improvement of 2.33 and 2.48 times was noticed for N-A2S and N-A3S columns. Compared to E-A1, percentage increase in stiffness modulus for E-A2S, E-A3S, and E-A4S were 114.06%, 89.75%, and 14.19% respectively. Corresponding increment for N-A2S, N-A3S, and N-A4S were 120.5%, 100.1%, and 19.95% respectively. In the case of toughness modulus similar behavior was noticed from experimental and numerical results. Enhancement in energy ductility was 77.36%, 42.95%, and 15.7% for E-A2S, E-A3S, and E-A4S columns, compared to the control column. Corresponding increment for N-A2S, N-A3S, and N-A4S were 64.12%, 44.16%, and 23.14% respectively. Effective grouting in conjunction with extra wrapping layers improved the structural behavior of low-grade concrete columns.