PSI - Issue 44

Sara S. Lucchini et al. / Procedia Structural Integrity 44 (2023) 2206–2213 Lucchini et al. / Structural Integrity Procedia 00 (2022) 000–000

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the steel connectors between masonry and coating play an important role in preventing shear slips mechanisms as well as the delamination of the SFRM layer. Finally, a further feature that deserves to be underlined is the effect of vertical restraints on the resistance of the member. In fact, the RC chord of the building prevents the wall from vertically elongating, thus causing a progressive increment of the axial load as the horizontal OP deflection increases. The numerical analyses predicted a maximum increment of the initial axial load of about 500% and 700% for the bare and the retrofitted walls, respectively.

Table 2. Summary of the main experimental and numerical results. Positive loading direction

Negative loading direction

K i (kN/mm) P max (kN)

d max (mm)

d 85% (mm)

K i (kN/mm) P peak (kN)

d max (mm)

d 85% (mm)

Cyclic test

+40.0 +33.2 +37.5 +19.0

+76.4 +88.5 +88.4 +50.2

+3.0 +4.8 +2.7 +5.3

+4.7 +7.4 +6.3 +5.7

-48.0

-68.0 -58.5 -71.4 -50.2

-6

-11.6

Monotonic test Retrofitted wall *

-

-1.6 -3.9 -5.3

-9.5 -4.9 -5.7

-52.0 -19.0

Bare wall *

* Numerical analysis

3. Conclusions The paper reports the results of reverse cyclic and monotonic experimental tests involving two one-way URM walls subjected to out-of-plane bending. The two bearing walls are part of a test building with rigid floors that is strengthened with a 30 mm thick layer of SFRM applied on the building façade only. As compared to the un-strengthened wall, whose behavior was studied numerically only, the tests proved the ability of the SFRM coating to provide a minimum increment of the bending resistance and the initial stiffness of 50% and 70%, respectively. Irrespective of the single sided SFRM strengthening, the two test walls presented approximately the same maximum resistance both in the positive and negative loading direction. This result can be explained considering the contribution to the flexural resistance provided by the SFRM coating to the top-end and bottom-end cross-sections of the wall. Furthermore, the numerical simulations highlighted the important role of masonry-to-coating connectors in preventing the potential delamination/detachment of the SFRM coating from the masonry surface. Acknowledgements The research work was part of the Health&Wealth project “Sismacomf” financially supported by the University of Brescia and by Tecnologia e Ricerca Italiana S.r.l. (TRI S.r.l). The authors want to thank the Italian Department of Civil Protection that supported the present research in the framework of the project ReLUIS-DPC 2019-21. References Bellini, A., Incerti, A., Mazzotti, C., 2017. Out-of-plane strengthening of masonry walls with FRCM composite materials. Key engineering materials, 747, 158-165, Trans Tech Publications Ltd. Donnini, J., Maracchini, G., Lenci, S., Corinaldesi, V., Quagliarini, E., 2021. TRM reinforced tuff and fired clay brick masonry: Experimental and analytical investigation on their in-plane and out-of-plane behavior. Construction and Building Materials, 272, 121643. Facconi, L., Minelli, F., Lucchini, S., Plizzari, G., 2020. Experimental study of solid and hollow clay brick masonry walls retrofitted by steel fiber reinforced mortar coating. Journal of Earthquake Engineering, 24(3), 381-402. Gattesco, N., Boem, I., 2020. Evaluation of the out-of-plane performances of masonry walls strengthened with composite reinforced mortar. In Brick and Block Masonry-From Historical to Sustainable Masonry, 632-639. CRC Press. Lucchini, S. S., Facconi, L., Minelli, F., Plizzari, G., 2021. Cyclic Test on a Full-Scale Unreinforced Masonry Building Repaired with Steel Fiber Reinforced Mortar Coating. Journal of Structural Engineering, 147(6). Meriggi, P., de Felice, G., De Santis, S., 2020. Design of the out-of-plane strengthening of masonry walls with fabric reinforced cementitious matrix composites. Construction and Building Materials, 240, 117946. Valluzzi, M. R., Da Porto, F., Garbin, E., Panizza, M., 2014. Out-of-plane behaviour of infill masonry panels strengthened with composite materials. Materials and structures, 47(12), 2131-2145.