Feasibility and Mechanistic Insights into Various Strengthening Techniques for Augmenting the Flexural Performance of Masonry under Fatigue Loading

Masonry structures, a predominant housing type, are susceptible to damage from lateral loading. Particularly, structures alongside roads and railway lines frequently undergo repeated loading, subjecting them to significant stress cycles over time. This cyclic stress accumulation may lead to fatigue-induced failure without warning, often manifesting as brittle fractures. Moreover, the cumulative effect of these stress cycles gradually decreases the load capacity. Therefore, the current study introduces two strengthening techniques (external and internal) for masonry structures undergoing repeated cyclic loading. External strengthening employed confinement through geonet and caging action using polypropylene (PP) band, while internal strengthening involved PP, polyethylene terephthalate (PET), nylon, steel, and coir fibers to reinforce mortar used for constructing masonry wallettes. Experiments were conducted on mortar cubes and prisms to assess compressive and flexural strengths. Further, masonry wallettes were cast and tested to evaluate the strengthening technique’s efficacy on flexural behavior. Additionally, three critical parameters— economy, buildability, and sustainability aspects of the strengthened specimens—were compared with the unstrengthened specimens. Most of the specimens exhibited enhanced performance, with flexural strength, stiffness, and energy absorption capacity per unit volume improving by up to 2.7, 19, and 43.2 times, respectively. The strengthened wallettes showed the ability to delay failure, ultimately leading to a more ductile failure mode. This improvement was accompanied by effective control over crack width and propagation, indicating greater structural resilience. The PP band strengthening method outperformed other strengthening methods in terms of flexural behavior. Further, all the strengthening methods were economical, sustainable, and buildable. Among all, PET fiber reinforcement was the most sustainable method for strengthening masonry.