Experimental investigation and numerical analysis of bond behavior in SRG-strengthened masonry prisms using UHTSS and stainless-steel fibers

This paper deals with the experimental and numerical study of the bond behavior of two steel reinforced grout (SRG)-strengthened masonry systems. Ten shear bond tests were carried out on prismatic masonry specimens. The data of experimental tests are recorded and results are given in terms of load/stress-global slip curves, failure modes, tables, graphs and photographic reports, comparing the results of the two strengthening systems. Two kinds of steel fibers available in marketplace were used: ultra-high tensile strength steel galvanized micro-cords and stainless-steel strands. The main target is to obtain information on the behavior of the bond between masonry surface and the two types of SRG composites, which are characterized by two substantial differences: tensile strength with a ratio of 2.4 and the corresponding surface mass density with a ratio of 0.30. Finally, the influence of the matrices coupled with the two systems is critically analyzed. The characterization of the bond behavior is necessary in order to confirm the performance of the SRG systems that have become increasingly used and attractive. It also aims to make a contribution to the existing knowledge especially in relation to the use of low resistance steel fibers (stainless steel) which are still few studied today. Furthermore, using a suitable interface law proposed in the literature, a numerical model is defined and employed to simulate the behavior of the specimens tested in the laboratory. The comparisons show a good agreement between numerical and experimental results in terms of the maximum load, load versus global-slip curves, and crack patterns.