Experimental and Numerical Studies on The Behavior of RC Exterior Beam-Column Joints Strengthened with Fiber Sheets Under Cyclic Loads

Beam-column joints are critical regions in reinforced concrete (RC) buildings and are most susceptible to seismic loads. Many retrofitting works using fiber-reinforced polymer (FRP) composites are performed in developed countries. This study combines experimental and numerical methods to assess the seismic behavior of seven RC beam-column joints specimens. Carbon fiber sheet, glass fiber sheet, and hybrid fiber (carbon + glass) were used for strengthening. One control specimen, two carbon wrapping specimens, two glass wrapping specimens, and two hybrid wrapping specimens selected to represent different strengthening schemes. Controlled displacement cyclic loading scenario at a frequency of 0.05 Hz was chosen to simulate seismic loading. Behavior of strengthening joints was studied using the following indices: first cracking and ultimate loads, energy dissipation, ductility, and stiffness. Numerical modeling for the RC beam-column joints specimens using ANSYS software package were created and analyzed. Testing results of different strengthening schemes were compared to both control specimen's results and those from numerical models. Results showed that the hybrid combination was more effective for improving the ductility by 29%, and dissipating energy by 54% of the beam-column joints at a high cost. Furthermore, itwas concluded that the proposed numerical model is adequate to describe the behavior of RC exterior beam-column joints strengthened with fiber sheets.