Out-of-plane testing of masonry infills strengthened using fibre reinforced matrix with prior in-plane damage

Performance of fibre reinforced cementitious matrix (FRCM) strengthened masonry infills under sequential bi-directional earthquake induced lateral loading, which is far from well-understood, was experimentally investigated herein. A total of eight single bay reinforced concrete frames were constructed with unreinforced hollow concrete masonry infills, of these one was tested non-retrofitted that served as control test assembly and the remainder were strengthened using varying FRCM types and configurations. The test assemblies were subjected to cyclic in-plane loading gradually increasing to 1% story drift, replicating lateral loading due to a moderate earthquake. These already in-plane damaged test assemblies were then subjected to gradually increasing monotonic OOP loading until failure. Resulting damage patterns, failure mechanisms, measured force-displacement response and stiffness characteristics were discussed. FRCM strengthening delayed the onset of out-of-plane cracking, instigated a more controlled failure mode, with strengthened infills exhibiting out-of-plane strength of 1.7–2.0 times that of the control specimen.