Strengthening of reinforced concrete columns by High-Performance Fiber-Reinforced Cementitious Composite (HPFRC) sprayed mortar with strengthening bars

• Published in: Composite structures 2018-10, Vol.202, p.1078-1086
• Main Authors: Cho, Chang-Geun, Han, Byung-Chan, Lim, Seung-Chan, Morii, Noharu, Kim, Jae-Whan
• Format: Article
• Language: English
• Subjects: Engineered Cementitious Composite (ECC); High-Performance Fiber-Reinforced Cementitious Composite (HPFRC); Reinforced concrete column; Seismic retrofit; Sprayed mortar
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2018.05.045

•Seismic strengthening of concrete column was newly applied by HPFRC sprayed mortar.•Damage of column plastic hinge was minimized by HPFRC and additional reinforcing bars.•The crack width of concrete was controlled by multiple micro-cracks induced by HPFRC.•The strengthened method could improve the hysteretic damping energy of the column. Under severe earthquake, lack of strength and ductility in the plastic hinge region of the reinforced concrete column raises serious concerns for overall structural safety. In the current study, experimental research was performed to improve the seismic strength and performance of reinforced concrete columns under cyclic load reversals. A new strengthening approach of reinforced concrete columns was introduced by applying High-Performance Fiber-Reinforced Cementitious Composites (HPFRC) sprayed mortar combined with additional reinforcing steel bars. For the practice of strengthening of old reinforced concrete columns, the surface of old concrete column section was treated and grooved in advance, later the longitudinal and/or transverse strengthening bars were placed in the groove of concrete surface, and finally the column section was increased by HPFRC sprayed mortar. As experimental variables such as the HPFRC sprayed mortar, use of additional transverse strengthening bars, and the use of additional longitudinal strengthening bars, the performance of the strengthened columns were compared with that of the conventional reinforced concrete column under reversed cyclic loads.