Historic masonry aggregates, commonly found in Italian historical centers, pose distinct challenges for seismic assessment due to their geometric irregularities, construction heterogeneity, and fragmented ownership. This study investigates the effectiveness of localized seismic strengthening applied to individual Structural Units (SUs) within an irregular masonry aggregate located in Arquata del Tronto (Italy). Nonlinear static (pushover) analyzes based on the Equivalent Frame Method were carried out to evaluate the impact of strengthening interventions, namely reinforced plaster and grout injection, on both the local response of individual structural units and the global behavior of the entire aggregate. The results indicate that while localized interventions can significantly enhance stiffness, strength, or ductility at the unit level, they do not consistently improve the global seismic performance of the aggregate. In several cases, performance indices on the aggregate scale remain unchanged or even deteriorate due to interaction effects and discontinuities between retrofitted and non-retrofitted units. These findings underscore the limitations of strategies based solely on isolated interventions and emphasize the importance of integrated assessments at the aggregate level. When full-scale modeling is not feasible, the priority should be given to mitigating local collapse mechanisms as a preliminary step to reduce seismic risk.
MicelliFCascardiA. Structural assessment and seismic analysis of a 14th century masonry tower. Eng Fail Anal2020; 107(5): 104198.
2.
SandovalCValledorRLopez-GarciaD. Numerical assessment of accumulated seismic damage in a historic masonry building. A case study. Int J Archit Herit2017; 11(8): 1177–1194.
3.
FormisanoAAdemovicN. An overview on seismic analysis of masonry building aggregates. Front Built Environ2022; 8: 966281.
4.
AcitoMBuzzettiMCundariGA, et al. General methodological approach for the et al. seismic assessment of masonry aggregates. Structures2023; 57(10): 105177.
5.
AngiolilliMPinascoSCattariS, et al. On the vulnerability features of historical masonry buildings in aggregate. Procedia Struct Integr2023; 44(5): 2074–2081.
6.
Di ChiccoRChieffoNFormisanoA. Exposure and seismic vulnerability of masonry buildings grouped in aggregate of a typical historical centre in the Basilicata region of Italy. J Build Eng2024; 94: 109859.
7.
AngiolilliMLagomarsinoSCattariS, et al. Seismic fragility assessment of existing masonry buildings in aggregate. Eng Struct2021; 247: 113218.
8.
PennaARostiARotaM. Seismic response of masonry building aggregates in historic centres: observations, analyses and tests. In: BentoRDe StefanoMKöberD, et al. (eds) Seismic behaviour and design of irregular and complex civil structures IV. Cham, Switzerland: Springer, 2022, pp.19–36.
9.
Di TrapaniFVillarSDi BenedettoM, et al. Seismic response of unreinforced masonry building aggregates: investigation on the aggregate-effect based on an elementary building aggregate. Eng Struct2024; 316(6): 118301.
10.
CardosoRLopesMBentoR. Seismic evaluation of old masonry buildings. Part I: method description and application to a case-study. Eng Struct2005; 27(14): 2024–2035.
11.
BorriACorradiMCastoriG, et al. A method for the analysis and classification of historic masonry. Bull Earthq Eng2015; 13: 2647–2665.
12.
BorriACorradiMDe MariaA. The failure of masonry walls by disaggregation and the masonry quality index. Heritage2020; 3(4): 1162–1198.
13.
AngiolilliMBrunelliACattariS. Fragility curves of masonry buildings in aggregate accounting for local mechanisms and site effects. Bull Earthq Eng2023; 21(5): 2877–2919.
14.
LeggieriVLiguoriFSRuggieriS, et al. Seismic fragility evaluation of typological masonry aggregates accounting for local collapse mechanisms. In: COMPDYN 2023 Proceedings, Athens, Greece, 12–14 June 2023, vol. 1, pp.1–14. National Technical University of Athens.
15.
FormisanoAChieffoNMiloB, et al. The influence of local mechanisms on large scale seismic vulnerability estimation of masonry building aggregates. AIP Conf Proc2016; 1790: 130010.
16.
FormisanoAFabbrocinoFVaianoG. Parametric analysis of the seismic response of masonry bell towers. AIP Conf Proc2019; 2116: 220004.
17.
LourençoPB. Masonry structures, overview. In: BeerMKougioumtzoglouIAPatelliE, et al. (eds) Encyclopedia of earthquake engineering, Berlin: Springer, 2014, pp.1–9.
18.
ValenteMMilaniGGrandeE, et al. Historical masonry building aggregates: advanced numerical insight for an effective seismic assessment on two row housing compounds. Eng Struct2019; 190: 360–379.
19.
GrillandaNValenteMMilaniG, et al. Advanced numerical strategies for seismic assessment of historical masonry aggregates. Eng Struct2020; 212: 110441.
20.
FormisanoAMassimillaA. A novel procedure for simplified nonlinear numerical modeling of structural units in masonry aggregates. Int J Archit Herit2018; 12(7–8): 1162–1170.
21.
VaianoGD’AmatoMFormisanoA. Seismic vulnerability comparative assessment of some samples of churches affected by the last Italian earthquakes. In: Proc EURODYN 2020, XI International Conference on Structural Dynamics, Athens, Greece, 23–26 November 2020, vol. 2, pp.4318–4329. National Technical University of Athens.
22.
FormisanoAMazzolaniFMFlorioG, et alA quick methodology for seismic vulnerability assessment of historical masonry aggregates. In: Proc COST Action C26 Final Conference “Urban Habitat Constructions Under Catastrophic Events”, Naples, 16–18 September 2010, pp.16–18. CRC Press.
23.
DianaLVaianoGFormisanoA, et al. The seismic vulnerability assessment of heritage buildings: a holistic methodology for masonry churches. Int J Archit Herit2024; 18(6): 994–1022.
24.
BernabeiLVaianoGRossoF, et al. A novel seismic vulnerability assessment of masonry facades: framing and validation on Caldarola case study after 2016 central Italy earthquake. Technol Eng Mater Archit2021; 7(2): 28–41.
25.
LiSLiuH. Statistical and vulnerability prediction model considering empirical seismic damage to masonry structures. Structures2022; 39(1): 147–163.
26.
ShabaniAKioumarsiMZucconiM. State of the art of simplified analytical methods for seismic vulnerability assessment of unreinforced masonry buildings. Eng Struct2021; 239: 112280.
27.
CardinaliVCristofaroMTFerriniM, et al. An interdisciplinary approach for the seismic vulnerability assessment of historical centres in masonry building aggregates: application to the city of Scarperia, Italy. In: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Valencia, Spain, 9–12 September 2020, vol. 44, pp.667–674. Copernicus Publications.
28.
CardinaliVTanganelliMBentoR. A hybrid approach for the seismic vulnerability assessment of the modern residential masonry buildings. Int J Disaster Risk Reduct2022; 79: 103193.
29.
WangPMilaniG. Seismic vulnerability prediction of masonry aggregates: iterative finite element upper bound limit analysis approximating no tensile resistance. Eng Struct2023; 293(4): 116595.
30.
JohnSKCascardiAVerreS, et al. RC-columns subjected to lateral cyclic force with different FRCM-strengthening schemes: experimental and numerical investigation. Bull Earthq Eng2025; 23(4): 1561–1590.
31.
OmbresLAielloMACascardiAVerreS. Modeling of steel-reinforced grout composite system-to-concrete bond capacity using artificial neural networks. J Compos Constr Advance online publication July 8, 2024. https://doi.org/10.1061/JCCOF2.CCENG-445
32.
FabbrocinoFOlivieriCLucianoR, et al. Seismic performance of historic masonry buildings: a comparative analysis of equivalent frame and block-based methods. Alex Eng J2024; 109: 359–375.
33.
VaianoGVenanziIFormisanoA, et al. Seismic behaviour of isolated and aggregate masonry tower: the case study of the sciri tower in Perugia. In: Proc COMPDYN2019 7th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, Crete Island, Greece, 24–26 June 2019.
34.
PerelliFLDe GregorioDMontaninoA, et al. Energy-based modelling of in-plane fragility curves for the 2D ultimate capacity of Italian masonry buildings. Front Built Environ2023; 9: 1127523.
35.
FormisanoAVaianoGFabbrocinoF, et al. Seismic vulnerability of Italian masonry churches: the case of the nativity of blessed Virgin Mary in Stellata of Bondeno. J Build Eng2018; 20: 179–200.
36.
CrespinoEAdriaenssensSFraddosioA, et al. A multi-objective optimization approach for novel shell/frame systems under seismic load. Structures2024; 65: 106625.
37.
OlivieriCIannuzzoAMontaninoA, et al. A continuous stress-based form finding approach for compressed membranes. Int J Mason Res Innov2024; 9(5–6): 585–605.
38.
SarhosisVMilaniGFormisanoA, et al. Evaluation of different approaches for the estimation of the seismic vulnerability of masonry towers. Bull Earthq Eng2018; 16: 1511–1545.
39.
MalomoDDeJongMJ. A macro-distinct element model (M-DEM) for simulating the in-plane cyclic behavior of URM structures. Eng Struct2021; 227(1): 111428.
40.
ValluzziMRSalvalaggioMLorenzoniF, et al. The engineering approach to conservation of massive archaeological structures in seismic areas: the Apollo nymphaeum in Hierapolis of Phrygia. Int J Archit Herit2023; 17(9): 1590–1606
41.
LaiMParisVFabbrocinoF, et alStructural behaviour of English serpentine walls for architectural heritage preservation. In: Proc GIMC-SIMAI Workshop for Young Scientists, Naples, Italy, 10–12 July 2024, pp.135–141. Springer.
42.
OlivieriCCockingSFabbrocinoF, et al. Seismic capacity of purely compressed shells based on airy stress function. Contin Mech Thermodyn2025; 37(2): 21.
43.
IannuzzoAVan MeleTBlockP. Piecewise rigid displacement (PRD) method: a limit analysis-based approach to detect mechanisms and internal forces through two dual energy criteria. Mech Res Commun2020; 107: 103557.
44.
MascoloIGesualdoAOlivieriC, et al. On blocks detection in unilateral masonry-like structures: a rigid-elastic displacement approach. Int J Mason Res Innov2022; 7(4): 395–405.
45.
IannuzzoAMusoneVRuoccoE. A neural network-based automated methodology to identify the crack causes in masonry structures. Comput Aided Civ Infrastruct Eng2024; 39(24): 3769–3785.
46.
IannuzzoAMallardoV. A novel approach to model differential settlements and crack patterns in masonry structures. Eng Struct2025; 323: 119220.
47.
OlivieriCIannuzzoAFortunatoA, et al. The effect of concentrated loads on open-well masonry spiral stairs. Eng Struct2022; 272(2): 114952.
48.
FerreroCCusanoCYavuzerMN, et al. When cracks are (not) a structural concern: the case of ’Giovanni Vinciguerra’ school in Anagni. Int J Mason Res Innov2022; 7(1–2): 217–232.
49.
MontaninoAIannuzzoA. A quadrilateral plate-type finite element to model stress singularities in no-tension materials. Comput Methods Appl Mech Eng2024; 432: 117433.
50.
ValenteMMilaniG. Non-linear dynamic and static analyses on eight historical masonry towers in the north-east of Italy. Eng Struct2016; 114: 241–270.
51.
OlivieriC. FORMERLY-Math: constrained form-finding through membrane equilibrium analysis in Mathematica. Softw Impacts2023; 16: 100512.
52.
CutoloAGuarracinoFOlivieriC, et al. Nonlinear FE analysis of a masonry spiral staircase in Nisida: a refined numerical case study. Int J Multiscale Comput Eng2022; 20(5): 105–114.
53.
CastellanoAEliaIFraddosioA, et al. A new experimental approach for small-scale dynamic tests on masonry arches aimed at seismic assessment. Int J Mason Res Innov2022; 7(1–2): 89–112.
54.
OlivieriCAdriaenssensSCennamoC. A novel graphical assessment approach for compressed curved structures under vertical loading. Int J Space Struct2023; 38(2): 141–155.
55.
CascardiAVerreSOmbresL, et al. Carbon fabric reinforced cementitious mortar confinement of concrete cylinders: the matrix effect for multi-ply wrapping. Compos Struct2024; 332(1): 117919.
56.
CarloniCVerreSSneedLH, et al. Open issues on the investigation of PBO FRCM-concrete debonding. Compos Struct2022; 299(9): 116062.
57.
MicelliFCascardiAAielloMA. A study on FRP-confined concrete in presence of different preload levels. In: Proceedings of the 9th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering—CICE, Paris, France, 2018, pp. 17–19.
58.
OlivieriCSibilleLCockingS, et al. Design of purely compressive shells under vertical and horizontal loads through Machine Learning-driven form-findingMech Res Commun2025; 148: 104491.
59.
ZampilliMBrunoriG. Ricostruire Arquata: Studi, Ricerche e Rilievi per la Redazione dei Piani e dei Programmi di Ricostruzione e Recupero dei Centri Storici del Comune di Arquata del Tronto. Rome: Roma TrE-Press, 2021.
60.
S.T.A.Software manual, Data: 3Muri User Manual Release 10.9.0, 2012.
61.
FormisanoAChieffoNVaianoG. Seismic vulnerability assessment and strengthening interventions of structural units of a typical clustered masonry building in the Campania region of Italy. GeoHazards2021; 2(2): 101–119.
62.
Ministry of Infrastructure and Transport. Instructions for the Application of the New Technical Code for Constructions. Official Gazette of the Italian Republic No. 35 of 11-02-2019 (in Italian). Circolare esplicativa alle NTC2018, 2019.
63.
Ministry of Infrastructure and Transport. Technical Standards for Construction (NTC 2018). Official Gazette of the Italian Republic No. 42 of 20-02-2018 (in Italian). Norme Tecniche per le Costruzioni, 2018.
64.
ReLUIS, Dipartimento della Protezione Civile.s Linee guida per il rilievo, l’analisi ed il progetto di interventi di riparazione e rafforzamento/miglioramento di edifici in aggregato. Technical report, ReLUIS, Dipartimento della Protezione Civile, Bozza, ottobre2010. https://www.researchgate.net/publication/276101560
65.
Di LudovicoMProtaAMoroniC, et al. Reconstruction process of damaged residential buildings outside historical centres after the L’aquila earthquake: part I—“light damage” reconstruction. Bull Earthq Eng2017; 15(2): 667–692.
