Seismic Behavior of RC Columns Strengthened with Textile-Reinforced Ultrahigh-Toughness Cementitious Composite Jackets

Textile-reinforced ultrahigh-toughness cementitious composite (UHTCC) jackets--herein referred to as TRU jackets--are an innovative strengthening system for reinforced concrete (RC) structures. The ductile UHTCC used for this jacket system exhibits better deformation compatibility with the textile than brittle mortar does. In this paper, we present an experimental study of the seismic performance of RC columns strengthened with TRU jackets using cyclic lateral loading tests. The results indicated that the TRU jacket could effectively restrain the development of cracks in the plastic hinge zone, delay stiffness deterioration, and significantly improve ductility and energy dissipation. Moreover, at a low stirrup ratio of 0.39%, the peak load of the jacketed columns was greatly enhanced compared to the peak load of the RC companion columns. With an increased number of textile layers, seismic performance was improved. When the ratio of axial force to axial capacity was increased from 0.15 to 0.30, ductility and energy dissipation did not drop for the TRU-jacketed columns. As the strengthening height decreased from 2.0 to 1.2 times the cross-sectional height of the columns, the seismic performance of the jacketed columns remained almost unchanged. A numerical model was developed for the seismic simulation of TRU-jacketed columns, and the predicted hysteresis curves agree well with the test data.