Enhancement of lateral load carrying capacity of reinforced concrete frames with improved eccentric steel brace retrofitting technique

The existing reinforced concrete (RC) buildings around the globe are at risk to earthquakes events due to various deficiencies arising for previous codes and construction execution. These vulnerable RC structures are retrofitted with different techniques to improve their seismic load carrying potential. One of the most used techniques, Eccentric Steel Bracing (ESB), has appeared as a favorable technique for enhancing the seismic strength of existing structures. In this study, the application of ESB along with the combination of epoxy is investigated. The ESB technique essentially involved attachment of steel plates to RC elements using epoxy and embedding the bolts. The study emphases the attachment of gusset plates to RC elements, utilizing the advantages of epoxy and embedding bolts to ensure a strong connection. A one-third scale RC Braced frame (M-model) is subjected to Quasi Static Loading Test (QSLT). The results of the M-model are compared with another identical braced frame (A-model) where epoxy and pedestals were not applied while external steel plates were connected solely with bolts. The results suggested that M-models showed an increase of 6.24% compared to 4.17% (A-model). However, the lateral load capacity of M-model reduced by 22.60% compared to A-model. The ultimate drift of M-Model enhanced by 8.62% whereas the same parameter recorded for A-Model was 3.39%. In conclusion, the ESB methodology applied in this research study showed a promising result to enhance the seismic performance of the existing structures at risk.