PSI - Issue 44

Sara S. Lucchini et al. / Procedia Structural Integrity 44 (2023) 2286–2293 Lucchini et al. / Structural Integrity Procedia 00 (2022) 000–000

2293

8

the resistances of the ten retrofitted piers provided an underestimation of the global resistance of 22%: 1410.1 kN versus 1805.5 kN. Regarding the failure modes, as reported in Table 7, after retrofitting, the building response was governed by flexure. Only pier X2 exhibited a diagonal shear failure and piers X4 and X6 were governed by sliding shear. The analytical mechanisms are quite consistent with the numerical crack patterns obtained in Midas FEA, also governed by flexure mechanisms.

Table 7. Real residential building: axial load and resistance of retrofitted piers. Direction +X Pier X1 Pier X2 Pier X3 Pier X4 Pier X5

Pier X6 155.99 191.16 183.00 153.30 182.69 153.30

Pier X7

Pier X8 107.55 134.76 183.70 157.21 129.33 129.33

Pier X9 125.51 153.07 191.30 172.31 145.75 145.75

Pier X10

Axial load N t [kN] Axial load N b [kN]

119.77 156.82 174.67 151.28 118.70 118.70

147.77 189.44 301.23 504.07

136.62 192.60 410.13 382.21

87.43

98.98

87.14

69.42 83.14 94.08 43.06 30.54 30.54

127.77 146.17

113.71

111.89 115.81

V R,t [kN] V R,s [kN] V R,flex [kN]

53.57 56.76 45.02 45.02

99.66

76.53 55.77 55.77

1067.01 330.76

111.01

V R [kN]

301.23

330.76

99.66

Predicted failure mode

F

D

F

S

F

S

F

F

F

F

4. Conclusions An analytical model able to predict the in-plane lateral resistance of masonry walls retrofitted by SFRM overlays was briefly presented and applied to two full-scale buildings. The analytical results were compared with experimental and numerical results. The schematization of masonry piers, based on the fracture lines expected after retrofitting, led to an analytical prediction of global seismic resistance on the safe side. The failure modes provided by the analytical model were quite consistent with the crack patterns exhibited by the experimental test as well as by the non-linear static analysis carried out with Midas FEA. The boundary conditions considered at the pier ends affected the global response of the structure generally leading to an underestimation of the maximum in-plane resistance. Acknowledgements The authors want to thank the Italian Department of Civil Protection that financially supported the present research within the project ReLUIS-DPC 2019-21. A special acknowledgment goes also to Eng. Federica Cuelli for her contribution in validating the analytical model proposed by the Authors. References Dolce, M., 1991. Schematizzazione e modellazione degli edifici in muratura soggetti ad azioni sismiche. Industria delle costruzioni, 25, 44-57. Facconi, L., Lucchini, S. S., Minelli, F., Grassi, B., Pilotelli, M., Plizzari, G. A., 2021. Innovative method for seismic and energy retrofitting of masonry buildings. Sustainability, 13(11), 6350. Giaretton, M., Dizhur, D., Garbin, E., Ingham, J. M., da Porto, F., 2018. In-plane strengthening of clay brick and block masonry walls using textile reinforced mortar. Journal of Composites for Construction, 22(5). NTC 2018, Italian Building Code. D.M. 17/01/2018: Technical code for constructions. Italian Ministry of Infrastructure and Transport, Rome, Italy (in Italian). Lin, Y. W., Wotherspoon, L., Scott, A., Ingham, J. M., 2014. In-plane strengthening of clay brick unreinforced masonry wallettes using ECC shotcrete. Engineering Structures, 66, 57-65. 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). DPC-ReLUIS 2019-2021 - WP 14: Contributi normativi relativi a Materiali Innovativi per Interventi su Costruzioni Esistenti. Indicazioni Progettuali per il Consolidamento di elementi strutturali in c.a. e muratura mediante HPFRC. Sevil, T., Baran, M., Bilir, T., Canbay, E., 2011. Use of steel fiber reinforced mortar for seismic strengthening. Construction and Building Materials, 25(2), 892-899.