Strengthening unreinforced masonry walls against out-of-plane loading using hemp fibers -

Abstract

Strengthening concrete masonry structures with fiber reinforced polymers is a method widely used for strengthening and rehabilitation purposes. Research on strengthening of masonry walls has been limited to the use of composites made from synthetic material such as carbon, glass or aramid fibers, etc. The existing knowledge in improving structures, including masonry walls, using natural fibers, is hardly applied. The replacement of synthetic fibers used as external reinforcement (carbon, glass and aramid) with natural fibers is a step to achieve a sustainable construction. The objective of this study is to investigate the out-of-plane flexural behavior of unreinforced masonry walls strengthened with externally applied natural hemp fiber fabric. The test parameters investigated were the amount of hemp reinforcement layers and anchoring of the hemp reinforcement. In this study, unstrengthened and hemp-strengthened masonry wall specimens were tested in the out-of-plane direction. The load-deflection curves, structural ductility measured by fracture energy and failure modes were analyzed. The ultimate moment capacity of the unstrengthened walls was estimated using a simple analytical approach. A proposed analytical model was used to determine the out-of-plane capacity of the hemp-strengthened walls. Results showed that externally bonded hemp fiber fabric composite systems significantly enhance the load carrying capacity and deflection capacity of unreinforced masonry walls subjected to out-of-plane loads. As the hemp reinforcement ratio increases, the flexural capacity and ductility of the walls also increase. The predicted ultimate load carrying capacities of strengthened and unstrengthened walls were considered conservative compared to experimental results.