Experimental and numerical study of bond between masonry and near-surface mounted steel bars

This addresses the bond between masonry and near surface mounted steel bars through experimental and numerical investigation. In the experimental program, 12 masonry prisms were prepared from commercial clay bricks and were strengthened using NSM steel bars fixed by cement mortar or epoxy; the prisms were subjected to pull-out testing and the failure loads and modes were studied. Numerical modeling and nonlinear analysis were made for the tested prisms using commercial software ANSYS.V.15. Comparison between experimental and numerical results showed good agreement regarding failure loads and failure modes which validates the efficiency of the adopted numerical modeling and nonlinear analysis approach. The numerical analysis showed that the widespread assumption of perfect bond between the strengthening bars and masonry gives misleading results, and therefore the behavior and resistance of the interface between steel bars and mortar/epoxy or between the mortar/epoxy and masonry should be adequately included in the modeling. Moreover, a numerical study was conducted to investigate the influence of several variables, namely the bar diameter and the embedment length, on the bond between NSM steel bars and masonry elements. The numerical study revealed that the failure load obviously increases with increase of embedment length and slightly with increasing the steel bar diameter.