Cyclic shear behavior of masonry walls strengthened with prestressed steel bars and glass fiber grids

Abstract

The present study developed a new and original strengthening method to enhance the shear capacity and ductility of unreinforced masonry (URM) walls based on the unbonded prestressed units using steel bars and glass fiber (GF) grids. The strengthening efficiency was validated through the experimental analyses including the failure mode, the lateral load-displacement relationship, shear capacity, and work damage indicator measured from four specimens subjected to a constant axial load and cyclic lateral loads. In addition, new design equations for the shear capacity of masonry walls were derived based on the regression analysis of 172 datasets. In particular, the proposed equations considered the shear enhancement by the axial stresses created due to the prestressed strengthening materials. The test results showed that shear capacity of the masonry walls strengthened with diagonal steel bars and GF grids increased by 4.2 times when compared with that of the companion URM walls. The proposed design equations for shear capacity of masonry walls also exhibited superior accuracy to FEMA 306 and EC 6 models.