•An out-of-plane capacity model for masonry panels was experimentally derived.•Bi-linear model represents actual rocking response better than rigid block one.•During rocking, damping is related not ...only to elastic impacts.
Out-of-plane mechanisms induced by earthquakes are typical of many masonry structures such as standing out elements (spires, battlements of fortresses, etc.) or portions of façade badly connected to the building. The displacement-based assessment procedures in standards are based on the hypothesis of rigid block, which sometimes is unable to represent their actual behaviour; furthermore, very few information is available on dissipation, which is assumed as an equivalent viscous damping, usually kept constant to 5%. The paper illustrates the results of an experimental campaign on three mock-ups subjected to static and dynamic out-of-plane actions with the aim to verify the reliability of these assumptions for traditional irregular stone masonry panels under rocking.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In light of the forthcoming second generation Eurocodes (EC), the results of conducted systematic in-plane cyclic and compressive tests on three-leaf stone masonry walls are discussed following new ...requirements and provisions. The new proposal for EC8-3 for existing buildings is based on partial factors safety approach, though it considers different uncertainties in defining input parameters for effective seismic performance-based assessment. Prior to its application, massive calibration effort will be needed since there is no standardized method for shear testing of masonry walls. In this paper, the performance limit states damage, resistance, and displacement capacities from conducted test results were evaluated and assessed through comparison with analytical solutions and imposed limit values, as stated in existing codes. The test results provide a much higher deformation capacity than the limits provided in both existing and new proposal of EC8-3 as well as those in the ASCE code provisions. The reason for this lies in the soft, "ductile" mortar for which the presumed resistance according to code provisions should be significantly higher when considering good quality ashlar three-leaf stone masonry.
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BFBNIB, NUK, PILJ, SAZU, UL, UM, UPUK
There is a lack of knowledge regarding the parameters needed for the effective seismic performance assessment of historical stone masonry buildings. The paper presents the results of an extensive ...experimental campaign consisting of four compression and fifteen in-plane cyclic shear tests on three-leaf ashlar stone masonry walls and its constituents. The morphology, level of vertical load, and testing boundary conditions were systematically varied, and their influence on the load-bearing and deformation capacities, stiffness, ductility and energy dissipation was analysed. Good consolidation of the inner core enables in-plane failure mechanism of the walls to occur without decisive out-of-plane damage. The boundary conditions applied significantly influence the failure modes and large deformation capacities obtained, whereas transverse connections in the case of a shear failure mechanism do not significantly influence the overall lateral in-plane response of walls.
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BFBNIB, NUK, PILJ, SAZU, UL, UM, UPUK
Existing unreinforced multi-leaf stone masonry (URM) buildings are one of the most earthquake prone types of construction. Failure typically occurs even at low levels of earthquake-induced loads, ...with the out-of-plane delamination of masonry leaves and consequent collapse of the whole façade. Although this issue has been tackled by several researchers, dynamic tests reproducing the earthquake behaviour of as-built and strengthened multi-leaf stone URM walls are very limited in the literature. In response to this lack, shake-table testing of eight full-scale multi-leaf stone masonry walls followed by dynamic modal identification was performed. The application of steel tie-rods in the wall cross-section, the injection of the inner-core using hydraulic lime-based grout, and a combination of the two techniques are presented herein as suitable interventions to enhance the monolithic behaviour of multi-leaf stone URM walls. Tying the outer masonry leaves together increased the seismic capacity by a factor of 1.8 compared to unreinforced condition, while injecting grout into the inner-core of the wall provided resistance to peak ground acceleration (PGA) that were 2.3–3.6 times the PGA resisted by as-built walls, depending on the quality in the execution of the intervention. The results obtained in the walls strengthened with both techniques were significantly related to the grout injection only.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Calibration of analytical models for the prediction of the compressive strength of consolidated three-leaf stone masonry.•Construction of 3 series of stone masonry walls (16 panels in total) for ...testing under compression.•In grouts with fgr/fwc,0 ratio higher than 5, grout strength does not contribute to the increase of the wall resistance.•The effect that the reduced scale has on the compressive strength is taken into account in the presented formulations.
This paper presents calibration of analytical models to predict the compressive strength of three-leaf stone masonry before and after consolidation with grout injection. Experimental results from previous campaigns were used, both published (Vintzileou and Tassios, 1995; Valluzzi et al., 2004; Vintzileou and Miltiadou-Fezans, 2008; Mazzon, 2010) 1–4 and from recent laboratory experiments at the University of Padova. As part of the present research work, three-leaf stone masonry panels in 1:1 and 2:3 scales, both in their original condition and consolidated with natural hydraulic lime-grout injections, were tested under monotonic and cyclic simple compression (Silva, 2012; Silva et al., 2014a,b) 5–7.
This work focuses on providing a data-enriched formula based on previous proposals by (Vintzileou and Tassios, 1995; Valluzzi et al., 2004; Vintzileou, 2007) 1, 2, 8 and also compiled in (Vintzileou, 2011) 9 to predict the compressive strength of three-leaf stone masonry before and after consolidation, together with analyses of the exploitation ranges of the formulations and grout compatibility. The effects of the reduced scale were also taken into account in the updated formulations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Assessment of multi-leaf stone masonry in earthquake-prone areas is mostly related to the evaluation of its texture, morphology, leaf detachment and structural cracking due to previous seismic ...activity, as well as disintegration due to material deterioration. For the plastered masonry with heritage or artistic value (paintings, frescoes etc.), both the type of structure and the extent of damage should be characterized with minimal interference to the structure, which could be overcome solely by non-destructive testing (NDT). However, due to the complexity of plastered multi-leaf masonry structure, the performance of well-known NDT methods could be significantly worsened. Therefore, as a prerequisite for applying NDT on multi-leaf stone masonry in practice, a validation process should be carried out. In this study, complementary ground penetrating radar (GPR) and infrared (IR) thermography measurements on plastered laboratory three-leaf stone masonry walls were performed. Apart from assessing the wall texture and morphology with the type of connection between the leaves, detection of gradual plaster delamination and crack propagation while subjecting the walls to an in-plane cyclic shear test was taken into account. The results showed that GPR could successfully visualize header stones passing through the whole depth of the specimen. The masonry texture behind the plaster could be well resolved by both methods, although GPR near-field effects worsened its localisation. For the detection of plaster delamination, IR thermography outperformed GPR by detecting delamination as small as 2mm as well as structural crack patterns, whereas GPR only detected delamination larger than 8mm. It was shown that the performance of both methods for defect detection could be further improved by image fusion based on unsupervised clustering methods.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In the paper, possibilities of correlation of structural damage and damage of attached artistic assets on multi-leaf stone masonry walls by means of destructive and non-destructive testing (NDT) ...methods are investigated. Results from two testing campaigns carried out at the University of Genoa and University of Ljubljana are briefly presented. In particular, diagonal tests with different levels of pre-compression and shear tests under different boundary conditions were carried out in Genoa and Ljubljana, respectively. During the tests, different damage limit states (DL) of both masonry walls (SE) and attached plasters (AA) were investigated by means of NDT’s. Two different types of rubble stone masonry were considered (uncoursed random rubble vs. coursed squared rubble). For AA the results are presented in relative form in dependence from the DL of SE. Obtained results are influenced both by the type of test and tested masonry. Results of NDT revealed strong potential and a need for data fusing of both investigated methods for the evaluation of the state of the degradation behind the plaster.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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