ABSTRACT
Low strength of the structural material can mainly be found in earthen vernacular and historical constructions, because they are most often made of locally available cheap materials. The intervention methods should provide enough strength and ductility to the masonry structure weakened by an earthquake. These masonry structures crack easily during main seismic excitation, losing their primarily resistance, and require quick protection methods against aftershocks. Natural fibers do not have as good mechanical properties as the most popular ones, but in many cases high strength of fibers is not so important, because the weakest element in the composite strengthening of masonry structures is brittle masonry substrate. When after earthquake a weak masonry substrate is strengthened using composites, because it generates lower stress in brittle substrate at the same deformation level. Efficiency of strengthening systems for earthquake is tested in laboratory using cyclic shear tests.
