Influence of spacing on flexural strength of FRP reinforced masonry walls

Abstract

This paper presents the results of experimental and analytical results for clay brick masonry walls that were reinforced with near-surface-mounted CRP strips and a number of different strip spacings. The total number of FRP used in each test was constant, only the strip spacing (and hence the number of strips) was varied. Each wall was subjected to monotonically increasing static load a the mid-height of each simply-supported wall so that the maximum bending moment in the wall occured at its mid-span where the load was applied. The results of the tests suggest that the maximum spacing for this reinforcement ratio was achieved as the failure mechanism for this case showed signs of changing from the intermediate crack debonding mechanism that was observed in all the other configurations to one where an in-plane shear crack, parallel to the strip, began to develop in line with the perpend joints nearest to the CFRP strip. It was concluded that for any larger strip spacings, this failure mechanism would govern. In all the walls, the flexural strength of the NSM CFRP reinforced walls was nearly ten times greater than the flexural strength of the unreinforced masonry wall. The equivalent horizontal accelaration corresponding to the failure load for the weakest of the FRP strengthened walls was nearly 8.5g, well in excess of the expected seismic demands. The displacements at wall failure wre also in the excess of 40 mm, significantly larger than the displacements at maximum (cracking) strength for the unreinforced walls.