Experimental response of thin RC walls seismically strengthened with steel plates

Abstract

In some Latin American countries, and especially in Colombia, the industrialized system of thin and slender walls has been chosen for the construction of residential buildings, thus reducing costs and increasing efficiency of construction processes. However, these walls differ considerably from traditional concrete wall system due to their reduced thickness, reinforcement detailing, and use of nonductile electro-welded reinforcement, which increases their seismic vulnerability, especially in tall buildings and in high seismic hazard zones. Strengthening proposals for walls with these specific characteristics of the industrialized system are scarce; therefore, it is necessary to evaluate alternatives that allow for improving their seismic performance. This article presents the experimental response of a thin wall that was brought to failure and subsequently repaired and strengthened with externally bonded steel plates to evaluate the effectiveness of the repair process and the strengthening. Additionally, the results of two thin walls externally strengthened with steel plates and bolts are presented, and their response is compared with that of the original walls. All the specimens were subjected to the same type of test under cyclical lateral load and constant axial load until failure. The behavior observed in the rehabilitated wall showed that it is possible to restore the stiffness of a wall that has previously been brought to a severe level of damage and increase its displacement capacity with the strengthening. In strengthened walls without previous damage, the displacement capacity was increased between 25 % and 43 %, reaching a roof drift of up to 2.0 % without a significant increase in resistance. A noticeable increase was obtained in the amount of dissipated energy (greater than 80 %), and the rupture of web reinforcement and buckling of longitudinal reinforcement of the boundaries were delayed for average drifts of 43 % and 32 % higher than in the original walls, respectively.