Experimentral Study on the Behavior and Retrofet of Clay Block Infill Frames under Out-of-Plane Loading Using Alkali-Resistant Glass Fiber

The performance of reinforced concrete frames with clay block infills during recent earthquakes, particularly the 2017 Kermanshah (Sarpol-e Zahab) earthquake, has shown significant damage primarily due to inadequate bracing or lack of bracing in infill frames. To address this issue, rehabilitation of infill frames using fibers is essential. The effectiveness of this reinforcement method can be evaluated through out-of-plane loading tests. The present research aims to provide a solution for rehabilitating clay block infill frames using alkali-resistant glass fibers. In this study, three 1:2 scale reinforced concrete frame specimens were tested: a concrete frame with clay block infill having a two-centimeter gap on each side, a concrete frame with clay block infill using separator wall posts at a two-centimeter distance, and a concrete frame with wall posts reinforced by alkali-resistant glass fibers. The perforated clay blocks used were standard-sized (25×20×10 cm) and were not scaled. Alkali-resistant glass fibers were used for structural reinforcement. Test results indicated that the specimen reinforced with alkali-resistant glass fibers exhibited significant performance improvements when compared to specimens with boundary condition infills and infills with wall posts, demonstrating an increase in out-of-plane force resistance by up to 110% and enhanced ductility (displacement capacity) by up to 150%. Moreover, this strengthening methodology not only transforms the infill behavior from brittle failure to ductile failure but also promotes progressive material degradation rather than sudden collapse.