Seismic Retrofit of Rectangular RC Columns Using CFRP Wrapping and CFRP Anchors

Seismic Retrofit of Rectangular RC Columns Using CFRP Wrapping and CFRP Anchors

In recent years, CFRP wrapping retrofit method has been studied and became one of the most common schemes used in the retrofit industry. Research results showed that rectangular columns retrofitted by CFRP wrapping were ineffective because of concrete crushing due to the bulging of column sides. The “CFRP wrapping coupled with CFRP anchors” retrofit method was proposed in 2006 at NCREE. Preliminary research on the application of CFRP anchors showed that these anchors enabled the concentrated stress at the corners of the column spread evenly. The objectives of this study include:(1) to develop the design criteria of CFRP anchors, and(2) to evaluate the efficency of the rectangular columns retrofitted by CFRP wrapping with CFRP anchors. A total of five full-scale specimens were constructed and tested of which one served as the as-built benchmark specimen. The other four specimens using CFRP wrapping and CFRP anchors could be divided into two major research groups: two specimens with focus on their shear capacity and the other two specimens with focus on their flexural ductility. Using a well-designed test frame, five specimens of RC columns were subjected to constant axial force and reverse-curvature moment during the cyclic loading tests. Experimental results demonstrated that the specimens retrofitted by CFRP wrapping conjugated with CFRP anchors showed improved hysteresis behavior compared with the specimen retrofitted with CFRP wrapping only. The moment capacity and ductility were enhanced as well.