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4 pages, 177 KiB

Open AccessEditorial

Editorial of the Special Issue “Seismic Vulnerability and Strengthening of Unreinforced Masonry Buildings”

by Antonio Formisano, Luigi Sorrentino and Maria Zucconi

Geosciences 2023, 13(3), 62; https://doi.org/10.3390/geosciences13030062 - 21 Feb 2023

Cited by 1 | Viewed by 1210

Abstract

Historical structures represent a significant percentage of existing constructions in numerous seismic-prone regions, and some of these are iconic monuments of their countries [...] Full article

(This article belongs to the Special Issue Seismic Vulnerability and Strengthening of Unreinforced Masonry Buildings)

Research

Jump to: Editorial

29 pages, 11966 KiB

Open AccessArticle

Damage to Churches after the 2016 Central Italy Seismic Sequence

by Barbara Ferracuti, Stefania Imperatore, Maria Zucconi and Silvia Colonna

Geosciences 2022, 12(3), 122; https://doi.org/10.3390/geosciences12030122 - 4 Mar 2022

Cited by 5 | Viewed by 3274

Abstract

The present study focuses on seismic damage to 36 masonry churches observed after the 2016 Central Italy earthquake. In the sample, recurrent architectural and structural features were identified and accurately described. In order to classify the churches in the sample based on their [...] Read more.

The present study focuses on seismic damage to 36 masonry churches observed after the 2016 Central Italy earthquake. In the sample, recurrent architectural and structural features were identified and accurately described. In order to classify the churches in the sample based on their safety level, their seismic vulnerability was assessed by adopting the simplified procedure proposed in the current Italian standards for cultural heritage. The observed damage, directly detected by the authors during the post-earthquake surveys, is presented and carefully described, highlighting the evolution of the damage. An analysis of the damage suffered by the inspected churches highlighted the most frequent causal mechanisms and the most vulnerable macroelements. Particular attention was devoted to computation of a damage index based on the observed damage as well as on the macroelements present in the surveyed churches. Moreover, a judgment of usability, i.e., whether a church could be occupied after a seismic event, was made using the official survey form and related to both the seismic intensity experienced and the observed damage index. An analysis of the collected data enabled consideration of the usability judgment with respect to the damage index values, computed according to the Italian standards. Full article

(This article belongs to the Special Issue Seismic Vulnerability and Strengthening of Unreinforced Masonry Buildings)

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17 pages, 12285 KiB

Open AccessArticle

Census-Based Typological Damage Fragility Curves and Seismic Risk Scenarios for Unreinforced Masonry Buildings

by Maria Zucconi and Luigi Sorrentino

Geosciences 2022, 12(1), 45; https://doi.org/10.3390/geosciences12010045 - 17 Jan 2022

Cited by 13 | Viewed by 2740

Abstract

Seismic risk assessment has become a crucial issue for optimal management of economic resources allocated to mitigation. For this purpose, in the last decades, several research activities were aimed to update hazard, exposure, and vulnerability models that contribute to seismic risk assessment. From [...] Read more.

Seismic risk assessment has become a crucial issue for optimal management of economic resources allocated to mitigation. For this purpose, in the last decades, several research activities were aimed to update hazard, exposure, and vulnerability models that contribute to seismic risk assessment. From this perspective, the present work focuses on developing new empirical damage fragility curves for census-based typological unreinforced masonry buildings. In particular, damage data observed after the 2009 L’Aquila earthquake, Italy, related to almost 57,000 residential buildings, were used to calibrate the fragility functions. These data were complemented with the census data with the aim of obtaining an accurate estimation of the number of undamaged buildings. Damage fragility curves were identified for typological building classes, defined considering parameters present in both post-earthquake observations and census data with the aim of extending the results to the whole national territory. Six typological classes were defined considering the categories of the construction timespan and of the state of repair parameters. Then, a further distinction of the typological classes considering the number of stories parameter was included where relevant. The fragility curves were defined as a function of peak ground acceleration for five damage states, defined according to the European macroseismic scale. The results confirmed that older buildings are more vulnerable than newer ones and highlighted the crucial role of the state of repair on the damage fragility curves. Finally, the new set of damage fragility functions was uploaded in the Italian Risk Maps information technology platform, used by the Civil Protection Department for risk evaluation, as an exemplification of the potential application of the fragility curves. Full article

(This article belongs to the Special Issue Seismic Vulnerability and Strengthening of Unreinforced Masonry Buildings)

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17 pages, 4623 KiB

Open AccessArticle

Experimental and Numerical Investigation of a Dissipative Connection for the Seismic Retrofit of Precast RC Industrial Sheds

by Virginio Quaglini, Carlo Pettorruso, Eleonora Bruschi and Luca Mari

Geosciences 2022, 12(1), 25; https://doi.org/10.3390/geosciences12010025 - 6 Jan 2022

Cited by 6 | Viewed by 2195

Abstract

Past earthquakes have highlighted the seismic vulnerability of prefabricated industrial sheds typical of past Italian building practices. Such buildings typically exhibited rigid collapse mechanisms due to the absence of rigid links between columns, beams, and roof elements. This study aims at presenting the [...] Read more.

Past earthquakes have highlighted the seismic vulnerability of prefabricated industrial sheds typical of past Italian building practices. Such buildings typically exhibited rigid collapse mechanisms due to the absence of rigid links between columns, beams, and roof elements. This study aims at presenting the experimental and numerical assessment of a novel dissipative connection system (DCS) designed to improve the seismic performance of prefabricated sheds. The device, which is placed on the top of columns, exploits the movement of a rigid slider on a sloped surface to dissipate seismic energy and control the lateral displacement of the beam, and to provide a recentering effect at the end of the earthquake. The backbone curve of the DCS, and the effect of vertical load, sliding velocity, and number of cycles were assessed in experimental tests conducted on a scaled prototype, according to a test protocol designed accounting for similarity requirements. In the second part of the study, non-linear dynamic analyses were performed on a finite element model of a portal frame implementing, at beam-column joints, either the DCS or a pure friction connection. The results highlighted the effectiveness of the DCS in controlling beam-to-column displacements, reducing shear forces on the top of columns, and limiting residual displacements that can accrue during ground motion sequences. Full article

(This article belongs to the Special Issue Seismic Vulnerability and Strengthening of Unreinforced Masonry Buildings)

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25 pages, 4669 KiB

Open AccessArticle

Nonlinear Dynamic Analysis of a Masonry Arch Bridge Accounting for Damage Evolution

by Daniela Addessi, Cristina Gatta, Mariacarla Nocera and Domenico Liberatore

Geosciences 2021, 11(8), 343; https://doi.org/10.3390/geosciences11080343 - 16 Aug 2021

Cited by 15 | Viewed by 2735

Abstract

This study investigates the nonlinear dynamic response of the masonry bridge ‘Ponte delle Torri’ in Spoleto, aiming at assessing the seismic performance of the structure and evaluating the occurring damaging mechanisms. A 3D Finite Element (FE) macromechanical procedure implemented in the FE program [...] Read more.

This study investigates the nonlinear dynamic response of the masonry bridge ‘Ponte delle Torri’ in Spoleto, aiming at assessing the seismic performance of the structure and evaluating the occurring damaging mechanisms. A 3D Finite Element (FE) macromechanical procedure implemented in the FE program FEAP is adopted to model the bridge. To reproduce the typical nonlinear microcracking process evolving in masonry material when subjected to external loads, an isotropic damage model is used. This is based on a scalar damage variable introduced in the stress-strain constitutive law and equally degrading all the components of the elastic constitutive operator. A nonlocal integral definition of the damage associated variable, that is the equivalent strain measure governing its evolution, is adopted to overcome the mesh dependency problems of the FE solution typically occurring in the presence of strain softening behavior. Based on the results of a recent study by some of the authors, a single equivalent pier is analyzed, whose geometry and boundary conditions are selected so that its response can provide useful information on the out-of-plane dynamic behavior of the overall bridge. To perform the seismic assessment, a set of recorded accelerograms is properly selected to simulate the seismic history of the Spoleto site. The nonlinear dynamic response of the structure is evaluated and monitored in terms of top displacement time history, evolution of the global damage index, and distribution of the damage variable. First, a set of analyses is performed by imposing the selected ground motions one by one on the initial undamaged configuration for the structure with the aim of emphasizing the damaging effects on its dynamic response. Then, the accelerograms are arranged in sequence to reproduce the seismic history of the site and analyze the influence of accumulated damage on the dynamic amplification of the response. A critical comparison of the bridge response to the sequence of accelerograms and the single records is made, and the interaction between the damaged structure dynamic response and the signal characteristic is highlighted, as well. Full article

(This article belongs to the Special Issue Seismic Vulnerability and Strengthening of Unreinforced Masonry Buildings)

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23 pages, 9573 KiB

Open AccessEditor’s ChoiceArticle

Seismic Vulnerability Assessment and Simplified Empirical Formulation for Predicting the Vibration Periods of Structural Units in Aggregate Configuration

by Nicola Chieffo, Antonio Formisano, Giovanni Mochi and Marius Mosoarca

Geosciences 2021, 11(7), 287; https://doi.org/10.3390/geosciences11070287 - 9 Jul 2021

Cited by 19 | Viewed by 2302

Abstract

The present research aims at investigating the vibration period of structural units (SUs) of a typical masonry aggregate located in the historical center of Mirandola, a municipality in the province of Modena. The clustered building consists of eighteen SUs mutually interconnected to each [...] Read more.

The present research aims at investigating the vibration period of structural units (SUs) of a typical masonry aggregate located in the historical center of Mirandola, a municipality in the province of Modena. The clustered building consists of eighteen SUs mutually interconnected to each other, which are characterized by solid brick walls and deformable floors. First of all, non-linear static analyses are performed by adopting the 3Muri software focusing on two distinct modelling techniques concerning the analyzed SUs in isolated and clustered configurations. Congruently to the procedure adopted, in order to evaluate a reliable seismic structural response of the SUs arranged in aggregate conditions, the contribution in terms of stiffness and mass derived from adjacent buildings is considered. The analysis results are represented in terms of risk factor, stiffness, and ductility. Secondly, the eigenvalue analysis is faithfully developed to identify the main vibration modes of the investigated SUs by proposing an empirical formulation, that allows for predicting the vibration period of structural units placed in aggregate configuration starting from the corresponding isolated ones. Finally, fragility functions are derived for both the heading and intermediate SUs to point out the expected damages under earthquakes with different intensities. Full article

(This article belongs to the Special Issue Seismic Vulnerability and Strengthening of Unreinforced Masonry Buildings)

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25 pages, 6885 KiB

Open AccessArticle

Experimental and Numerical Assessment of Seismic Retrofit Solutions for Stone Masonry Buildings

by Gabriele Guerrini, Christian Salvatori, Ilaria Senaldi and Andrea Penna

Geosciences 2021, 11(6), 230; https://doi.org/10.3390/geosciences11060230 - 27 May 2021

Cited by 7 | Viewed by 4644

Abstract

This paper presents an experimental and numerical study on different retrofit solutions for stone masonry buildings with timber diaphragms in earthquake-prone regions, aiming at enhancing wall-to-diaphragm connections, diaphragms’ stiffness, and masonry properties. The experimental results of incremental dynamic shake-table tests on three full-scale [...] Read more.

This paper presents an experimental and numerical study on different retrofit solutions for stone masonry buildings with timber diaphragms in earthquake-prone regions, aiming at enhancing wall-to-diaphragm connections, diaphragms’ stiffness, and masonry properties. The experimental results of incremental dynamic shake-table tests on three full-scale two-story buildings, complemented by material and component characterization tests, are initially summarized. The first building specimen was unstrengthened. The second one was retrofitted at the floor and roof levels with improved wall-to-diaphragm connections and a moderate increase in diaphragm stiffness. Connections were also improved in the third specimen together with a significant enhancement of diaphragm stiffness. The calibration of two numerical models, versus the experimental response of the retrofitted building specimens, is then presented. The models were further modified and reanalyzed to assess the effects of masonry mechanical upgrades, which could be achieved in practice through deep joint repointing or various types of jacketing. These solutions were simulated by applying correction coefficients to the masonry mechanical properties, as suggested by the Italian building code. The effectiveness of the experimentally implemented and numerically simulated interventions are discussed in terms of strength enhancement and failure modes. Full article

(This article belongs to the Special Issue Seismic Vulnerability and Strengthening of Unreinforced Masonry Buildings)

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20 pages, 6799 KiB

Open AccessArticle

FE vs. DE Modeling for the Nonlinear Dynamics of a Historic Church in Central Italy

by Angela Ferrante, Ersilia Giordano, Francesco Clementi, Gabriele Milani and Antonio Formisano

Geosciences 2021, 11(5), 189; https://doi.org/10.3390/geosciences11050189 - 27 Apr 2021

Cited by 38 | Viewed by 2807

Abstract

The present research paper properly focuses on the dynamics and failure mechanisms of the masonry “Apennine Church” of Santissimo Crocifisso in Pretare, municipality of Arquata del Tronto in the province of Ascoli Piceno (Marche region, Central Italy). Such a peculiar structural type traditionally [...] Read more.

The present research paper properly focuses on the dynamics and failure mechanisms of the masonry “Apennine Church” of Santissimo Crocifisso in Pretare, municipality of Arquata del Tronto in the province of Ascoli Piceno (Marche region, Central Italy). Such a peculiar structural type traditionally characterizes the intense seismic area of Central Italy, unfortunately almost totally damaged by the recent shock sequence of 2016. Advanced numerical modeling through discontinuous and continuous approaches were here utilized to have an insight into the dynamic properties and behavior of the structure under strong nonlinear dynamic excitations. In the discrete element approach, the non-smooth contact dynamics method, implemented in LMGC90©, was applied, adopting a full 3D detailed discretization. The church was schematized as an arrangement of rigid blocks, subjected to sliding by friction and perfect plastic collisions, with a null restitution coefficient. In the finite element approach, the concrete damaged plasticity model available in Midas FEA NX© was involved. This model allows reproducing the tensile cracking, the compressive crushing, and the degradation of the material under cyclic loads. Finally, the numerical analyses provided a valuable picture of the actual behavior of the church, thus giving useful hints for future strengthening interventions. Full article

(This article belongs to the Special Issue Seismic Vulnerability and Strengthening of Unreinforced Masonry Buildings)

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