Comparative evaluation of RC jacketing, friction-type dampers, and hybrid approaches for the seismic retrofitting of a reinforced concrete building

Abstract

In this study, a reinforced concrete (RC) building with inadequate seismic performance was designed below the requirements of TBEC 2018 and retrofitted using RC jacketing, friction dampers, and a hybrid approach. Subsequently, seismic performance, damage states, periods, and base shear forces were evaluated through nonlinear static pushover analyses, and their effects on cost were compared with those of the reference structure. Based on this study, it was determined that 50% of the ground and second-floor beams in the reference structure were identified at the Limited Damage (LD) level, while the remaining 50% were classified at the Moderate Damage (MD) level. Among the ground-floor columns, 36% were identified at the Advanced Damage (AD) level and 64% at the Collapse level. Above the second floor, all columns and beams in both the reference and retrofitted structures exhibited damage corresponding to the LD performance level. Accordingly, the reference structure was considered to have reached collapse in accordance with TBEC 2018. Following RC jacketing, 70% of the ground floor beams were identified at the LD level and 30% at the MD level, whereas all second-floor beams remained at the LD level. For the ground- and second-floor columns, 60% were identified at the LD level and 40% at the MD level, corresponding to the Life Safety (LS) or Controlled Damage (CD) performance level. Following friction damper retrofitting, 50% of the ground- and second-floor beams were identified at the LD level and 50% at the MD level. All ground-floor columns were classified at the MD level, whereas the second-floor columns were identified at the LD level, corresponding to the LS performance level. The hybrid retrofit resulted in 40% of the ground-floor columns being identified at the LD level and 60% at the MD level, while 72% of the second-floor columns were identified at the LD level and 28% at the MD level. Finally, 77.5% of the ground-floor beams were identified at the LD level and 22.5% at the MD level. Overall, all strengthening methods significantly improved seismic performance, while RC jacketing and the hybrid system reduced structural periods but increased base shear forces to approximately 1.5 times those of the reference structure. Consequently, foundation moments increased by 358% and 239% in the RC jacketed and hybrid systems, respectively, whereas the friction damper system showed only a 6% increase. These higher foundation demands may increase retrofitting-to-replacement cost ratios for the RC jacketing and hybrid systems. Thus, despite the improved seismic performance, retrofitting cost remains a key factor in strengthening strategy selection.