Flexural retrofit of support regions of reinforced concrete beams with anchored FRP ropes under reversed cyclic loading

摘要

Many studies have been conducted for enhancing the positive moment capacity of the mid-span areas of reinforced concrete (RC) beams strengthened with fiber reinforced polymer (FRP) reinforcement under monotonic increasing loads. However under seismic actions, the support regions of beams may also require retrofitting. In such cases, retrofitting should be effective under reversed cyclic flexural actions. According to the best knowledge of authors, there is no study investigating this important issue in the literature. Therefore, the present study focuses on retrofitting of beam support regions under reversed cyclic flexural moments. As the initial stage of a more comprehensive testing program, three full-scale RC beam-column-slab sub-assemblages were tested. The sub-assemblages also included a part of transverse beams perpendicular to the main beam tested. One specimen was tested as a reference specimen while the remaining two specimens were tested after being retrofitted with near surface mounted (NSM) carbon fiber reinforced polymer (CFRP) ropes with two different details in terms of anchorage of the CFRP ropes into joint region. The anchorage of CFRP ropes was provided by NSM application over the slab next to the column in one of the specimens, while CFRP rope was anchored by epoxy adhesive within the joint core by embedding it through a drilled hole on the column in other specimen. The effectiveness of the proposed anchoring methods was investigated through experimentally. The findings of the study indicated that the specimen retrofitted with NSM anchoring method achieved a remarkable enhancement in flexural capacity, whereas, anchoring through embedment of the CFRP rope within the epoxied drilled hole was not that successful.