Tezcan, Selman

Remus A., Tezcan S., Sun J., Milani G., Perucchio R.

The structural assessment of masonry construction often requires the use of nonlinear 2D and 3D finite element analysis. This work describes a strategy for using energy outputs from such analyses to accurately assess failure conditions precipitated by increasing lateral load. The methodology relies on the analogy between plastic strains and fracture that is inherent to the concrete damaged plasticity (CDP) macro-model used to represent the quasi-brittle behavior of masonry material. At critical conditions, energy imparted to a structure by loading can no longer be completely stored as elastic strain energy and must be dissipated. This occurs with fractures in masonry, which are represented with plastic strains when using CDP material. The development of plastic dissipation energy can therefore be used as a measure for understanding the progressive collapse of a structure, as we illustrate with the following three case studies analyzed using Abaqus/CAE Explicit: the massive earthen pyramid at Huaca de la Luna (Trujillo, Peru), the Roman pozzolanic concrete vault of Diocletian’s Frigidarium (Rome, Italy), and the mixed-material triumphal arch of the San Pedro Apóstol Church of Andahuaylillas (Peru). The method is verified by other measures of failure and has particular applicability for seismic analysis of complex masonry and earthen structures.

Taskan Z., Ozturk E., Tezcan S., Mindivan H.

Low-carbon steel has been widely used in various industrial applications and undergoes different surface treatments in contemporary practices to enhance wear resistance, corrosion resistance and hardness. Wear is a primary cause of damage to machine components under varying conditions like temperature, humidity, load and speed. This study focuses on improving wear resistance through coating applications. A reciprocal tribological test was conducted under a 30 N load with a 57.5 m sliding distance at 2500 cycles and 20 mm/s sliding speed. Two coatings, AISI 316L austenitic and AISI 420 martensitic stainless steel were applied using the HVOF method and subjected to plasma nitriding at 450 and 500 °C. Tests verified that the HVOF sprayed AISI 316L stainless steel coating nitrided at 450 °C offers the best wear resistance.

Remus A., Tezcan S., Sun J., Milani G., Perucchio R.

The structural assessment of masonry construction often requires the use of nonlinear 2- and 3D finite element analysis. This work describes a strategy for using energy outputs from such analyses to accurately assess failure conditions precipitated by increasing lateral load. The methodology relies on the analogy between plastic strains and fracture that is inherent to the concrete damaged plasticity (CDP) macro-model used to represent the quasi-brittle behavior of masonry material. At critical conditions, energy imparted to a structure by loading can no longer be completely stored as elastic strain energy and must be dissipated. This occurs with fractures in masonry, which are represented with plastic strains when using a CDP material. The development of plastic dissipation energy can therefore be used as a measure for understanding the progressive collapse of a structure, as we illustrate with three case studies analyzed using Abaqus/CAE Explicit: the massive, earthen pyramid at Huaca de la Luna (Trujillo, Peru), the Roman pozzolanic concrete vault of Diocletian’s Frigidarium (Rome, Italy), and mixed material triumphal arch of the San Pedro Apóstol Church of Andahuaylillas (Peru). The method is verified with other measures of failure and has particular applicability for seismic analysis of complex masonry and earthen structures.

Riccio C., Remus A., Tezcan S., Silva L.C., Milani G., Perucchio R.

This study contributes to the seismic structural failure analysis of the main pyramid of the archaeological complex Huaca de la Luna, Peru. Built with millions of adobe bricks by the Moche civilization (200–850C.E.), the monument is one of the largest adobe structures in the world. The monument shows signs of severe natural and anthropogenic damage due to its position along the Pacific Ring of Fire and extensive looting since Spanish colonial times. The pyramid was built as a succession of taller and larger platforms, each formed by erecting adjacent but disconnected vertical piers made of adobe masonry. A multiscale 2D nonlinear finite element (FE) model is introduced for assessing the contribution of this pier architecture to the structural response of the pyramid. The time-evolution of elastic strain and plastic dissipation energies is used to quantitatively track structural failure. The instant of structural collapse and attendant lateral capacity can be extracted from the point at which these energies match. Critical regions of a representative cross-section are modelled with individual piers represented by macroblocks and separated by frictional interfaces. A continuous description is adopted for the remaining part of the model. A nonlinear, two-dimensional (2D) plane strain analysis is conducted in Abaqus/CAE Explicit using concrete damaged plasticity and Mohr-Coulomb formulations for adobe construction and soft soil, respectively. A two-stage assessment procedure begins with a quasi-static analysis to predict the stress state due to gravitational load. A dynamic analysis follows to identify lateral capacity and failure mechanisms triggered by monotonically increasing ground acceleration. The development of local damage conditions up to structural collapse is visualized by the nucleation and propagation of maximum principal plastic strains throughout the model. A sensitivity analysis was conducted to evaluate the effect on lateral capacity of the contact friction coefficient between macroblocks and the number of macroblocks used to discretize the critical area. Introducing macroblocks to the model produces lateral capacities that are lower than analogous, purely-continuum models. These results are shown to be critically affected by the frictional coefficient that governs contact between the macroblocks. The results of this study offer critical insights on the consolidation strategy for the northwest corner of the pyramid and may find application to similarly-built historical earthen structures in northern Peru.

dos Santos M., Abelezele S., Korslund K., Cecil R., Tezcan S., Perucchio R.

Sun J., Tezcan S., Perucchio R.

Faleri F., Grillanda N., Tezcan S., Perucchio R., Milani G.

Tezcan S., Pando M.A., Aguilar R., Castañeda B., Rojas C., Perucchio R.

Tezcan S., Tambe N., Muir C., Aguilar R., Perucchio R.

The Saint Peter Apostle church of Andahuaylillas is a colonial church in the Cusco-Puno area of the Andes, dating to the late 16th or early 17th century and built primarily with adobe brick masonry. The church is characterized by a triumphal arch made with fired clay bricks and surmounted by a high tympanum of adobe masonry. The arch is stabilized by lateral walls of mixed stone-adobe construction. As part of the seismic assessment of the building, this work focuses on the evaluation of the triumphal arch subjected to in-plane lateral accelerations by pushover analysis based on nonlinear FE explicit formulation. Detailed 2- and 3D FE models are constructed from measurements taken on location and observed material distributions of adobe, fired bricks, and stone. The FE models are analyzed in Abaqus/CAE Explicit under gravitational loading and monotonically increasing lateral accelerations, simulating quasi-static conditions until collapse. The concrete damaged plasticity formulation is adopted to represent masonry materials with nonlinear tensile and compressive behavior based on the Lourenço’s model. Local and global collapse conditions are identified from the energy and reactions curves. The effects of lateral walls and their material composition, nave walls, and the brick arch on the lateral capacity the triumphal arch are systematically evaluated.

Cao V., Go G.

Buzzetti M., Pingaro N., Milani G.

Remus A., Tezcan S., Sun J., Milani G., Perucchio R.

The structural assessment of masonry construction often requires the use of nonlinear 2D and 3D finite element analysis. This work describes a strategy for using energy outputs from such analyses to accurately assess failure conditions precipitated by increasing lateral load. The methodology relies on the analogy between plastic strains and fracture that is inherent to the concrete damaged plasticity (CDP) macro-model used to represent the quasi-brittle behavior of masonry material. At critical conditions, energy imparted to a structure by loading can no longer be completely stored as elastic strain energy and must be dissipated. This occurs with fractures in masonry, which are represented with plastic strains when using CDP material. The development of plastic dissipation energy can therefore be used as a measure for understanding the progressive collapse of a structure, as we illustrate with the following three case studies analyzed using Abaqus/CAE Explicit: the massive earthen pyramid at Huaca de la Luna (Trujillo, Peru), the Roman pozzolanic concrete vault of Diocletian’s Frigidarium (Rome, Italy), and the mixed-material triumphal arch of the San Pedro Apóstol Church of Andahuaylillas (Peru). The method is verified by other measures of failure and has particular applicability for seismic analysis of complex masonry and earthen structures.

Remus A., Tezcan S., Pando M.A., Aguilar R., Perucchio R.

Aita D., Milani G., Taliercio A.

This contribution describes non-linear finite element analyses conducted to investigate the collapse behavior of the ogival dome with oculus and lantern of the Anime Sante church in L’Aquila, Italy. This dome, damaged significantly by a catastrophic earthquake in 2009, has been the focus of numerous studies on its structural behavior. The non-linear model utilized in this study, developed using Abaqus CAE software, aims to provide additional insights into the structural response, particularly focusing on the masonry that constitutes the dome. For this purpose, the dome is discretized into blocks and mortar joints. The mechanical behaviour of the mortar is described by means of a concrete damage plasticity model, with failure assumed to occur primarily at the interfaces between blocks. The preliminary analyses presented in this work consider gravitational loads, with an increasing vertical displacement applied at the crown to determine the collapse load. The resulting deformed shape of the dome and the location of plastic hinges are determined, alongside the study of collapse load through load-displacement diagrams. Furthermore, the results obtained from the finite element approach are compared with those derived from limit analysis methods. Specifically, novel versions of two classical approaches, grounded in the theoretical principles of lower and upper bound theorems, are referenced to assess the collapse load considering the strength of masonry. This comparative analysis serves to validate the numerical method employed in this study, enhancing confidence in the obtained results.

Cuadros-Rojas E., Saloustros S., Tarque N., Pelà L.

This research presents a cost-effective surveying methodology to assist the seismic assessment of complex heritage buildings, based on terrestrial structure-from-motion (SfM) photogrammetry. The method was applied to the study of the seismic performance of the church of San Juan Bautista – Inca temple of Huaytará, Peru, an emblematic case study due to its complex architecture and coexistence of different construction materials. The geometrical model for the seismic assessment was developed with an error of less than 2 % using SfM photogrammetry. Non-linear static pushover analyses were performed on 3D FEM models of the nave and the towers to evaluate their individual response under seismic loading. Mechanical properties of different structural materials of the church were evaluated based on laboratory experimental tests on mortar and adobe, contemporary and ancient fired brick, Inca stone, colonial stone and rubble stone units. Non-linear pushover analyses were conducted in four directions perpendicular to the perimeter walls, and the response of the structure was compared with the seismic demand specified in Peruvian Standards. The simulations show that damage-prone areas are the western and eastern facades, with cracking at the connections between orthogonal walls, as well as at the interface of adobe masonry with Inca stone masonry. The towers exhibit similar seismic response, with lower strength capacities compared to the main nave. In this case, flexural overturning mechanisms and cracking at the interface between stone and adobe masonry were observed. The displacement-based seismic assessment using the N2 method shows that a peak ground acceleration of 0.21 g could lead to the collapse of the north and south facades of the main nave. The towers showed a much smaller capacity with PGA leading to collapse of approximately 0.09 g. Overall, this study contributes to the understanding of the seismic performance of the Huaytará-Huancavelica church, highlighting vulnerabilities and providing valuable information for its preservation and future interventions. Future investigations should focus on on-site tests that will allow the estimation of the effect of existing damage on the structural response and their incorporation in the numerical model.

BENTO R., MILANI G., MOSOARCA M., SARHOSIS V.

Tezcan S., Pando M.A., Aguilar R., Perucchio R.

Huaca de la Luna is a monumental earthen complex near Trujillo in north coastal Peru built from 200 AD to 850 AD by the Moche civilization. Its principal structure – a stepped pyramid built with millions of adobe bricks on sloping bedrock and soft soil – presents severe structural damage at the NW corner. The static and dynamic response of the pyramid is systematically analyzed using 2D and 3D nonlinear FE models derived from a detailed evaluation of archaeological, material, and geotechnical data. The analyses are performed in Abaqus/CAE Explicit using concrete-damaged plasticity and Mohr-Coulomb formulation for adobe construction and soft soils, respectively. The time-evolution of elastic strain and dissipative plastic energy is used to follow the development of local damage conditions up to structural collapse. A critical cross-sectional configuration is identified through 2D FE plane strain sensitivity analysis of the static and lateral capacity to (a) pyramid stepped west side profile, (b) underlying bedrock configuration, and (c) adobe tensile strength. 3D models derived from the 2D critical configuration are then evaluated in terms of static stability, lateral capacity, and failure mechanisms. Results indicate that horizontal accelerations produce large structural failure at the pyramid northwest corner similar in extent and location to the present damage.

Remus A.M., Yılmaz L., Tezcan S., Perucchio R.

The Moche civilization constructed the monumental adobe complex Huaca de la Luna in phases from 100–650 CE. Its main stepped pyramid is the focus of this study. Located at the foot of Cerro Blanco, near coastal Trujillo, Perú, the structure is subject to Pacific Ring of Fire seismic activity. Damage to the northwest corner and looting on the north and west façades have motivated structural analysis using nonlinear FE models that treat the base of the pyramid as directly attached to the underlying sloping bedrock and soft soil. The present work introduces the following factors to a 2D cross-section model: (a) an interposing sand layer of varying thickness between the adobe construction and the sloping bedrock of Cerro Blanco, (b) a frictional interaction at this interface, and (c) architectural additions to the main pyramid’s east side. Using a Design of Experiments (DOE) methodology, this study investigates how these factors affect the monument’s lateral capacity, measured through the time-evolution of strain and plastic dissipation energy. Results indicate that the interposing sand layer and construction on the east side influence the results the most. Consequently, further on-site survey should focus on a more accurate definition of these features. Simulations are performed in Abaqus/CAE Explicit using the concrete damaged plasticity and the Mohr-Coulomb formulations for modeling adobe and sand, respectively. Statistical analysis is performed in the statistical software JMP version 16, primarily focusing on Analysis of Variance (ANOVA).

Riccio C., Remus A., Tezcan S., Silva L.C., Milani G., Perucchio R.

This study contributes to the structural assessment of the main pyramid in the archaeological complex of Huaca de la Luna, Peru. Built with millions of adobe bricks by the Moche civilization (200–850 A.D.), the monument is one of the largest adobe structures in the world. Located in a seismically active area, the monument shows signs of severe natural and anthropogenic damage. The pyramid was built as a succession of taller and larger platforms, each formed by erecting adjacent but disconnected vertical piers made of adobe masonry. A multiscale 2D nonlinear FE model is introduced for assessing the contribution of this pier architecture to the dynamic response of the pyramid. A representative cross-section of the pyramid is analyzed under plane strain conditions. Critical regions are modelled with individual piers represented by macroblocks separated by frictional interfaces, while a continuous description is adopted for the remaining part of the model. The analysis is performed in Abaqus/CAE Explicit using concrete-damaged plasticity and Mohr-Coulomb formulation for adobe construction and soft soils, respectively. The time-evolution of elastic strain and dissipative plastic energy is used to follow the development of local damage conditions up to structural collapse. The structural assessment includes (i) a quasi-static analysis aiming to predict the stress state due to gravitational loads, and (ii) dynamic analysis to identify lateral capacity and failure mechanisms triggered by monotonically increasing ground acceleration. Sensitivity analyses was conducted to evaluate the effect of the contact friction coefficient and the number of macro-blocks used to discretize the critical area.

Riccio C., Remus A., Tezcan S., Silva L.C., Milani G., Perucchio R.

This study contributes to the seismic structural failure analysis of the main pyramid of the archaeological complex Huaca de la Luna, Peru. Built with millions of adobe bricks by the Moche civilization (200–850C.E.), the monument is one of the largest adobe structures in the world. The monument shows signs of severe natural and anthropogenic damage due to its position along the Pacific Ring of Fire and extensive looting since Spanish colonial times. The pyramid was built as a succession of taller and larger platforms, each formed by erecting adjacent but disconnected vertical piers made of adobe masonry. A multiscale 2D nonlinear finite element (FE) model is introduced for assessing the contribution of this pier architecture to the structural response of the pyramid. The time-evolution of elastic strain and plastic dissipation energies is used to quantitatively track structural failure. The instant of structural collapse and attendant lateral capacity can be extracted from the point at which these energies match. Critical regions of a representative cross-section are modelled with individual piers represented by macroblocks and separated by frictional interfaces. A continuous description is adopted for the remaining part of the model. A nonlinear, two-dimensional (2D) plane strain analysis is conducted in Abaqus/CAE Explicit using concrete damaged plasticity and Mohr-Coulomb formulations for adobe construction and soft soil, respectively. A two-stage assessment procedure begins with a quasi-static analysis to predict the stress state due to gravitational load. A dynamic analysis follows to identify lateral capacity and failure mechanisms triggered by monotonically increasing ground acceleration. The development of local damage conditions up to structural collapse is visualized by the nucleation and propagation of maximum principal plastic strains throughout the model. A sensitivity analysis was conducted to evaluate the effect on lateral capacity of the contact friction coefficient between macroblocks and the number of macroblocks used to discretize the critical area. Introducing macroblocks to the model produces lateral capacities that are lower than analogous, purely-continuum models. These results are shown to be critically affected by the frictional coefficient that governs contact between the macroblocks. The results of this study offer critical insights on the consolidation strategy for the northwest corner of the pyramid and may find application to similarly-built historical earthen structures in northern Peru.

Almassri B., Safiyeh A.

Remus A., Tezcan S., Pando M.A., Aguilar R., Perucchio R.

Vitorino S., Corazzi R., Doz G.

The Cathedral of Santa Maria del Fiore was constructed in 1420 and features one of the largest masonry domes constructed without the use of reinforcement. The city of Florence is situated between two zones of seismic activity, namely Mugello and Chianti, and has been affected by earthquakes in recent years. The objective of the present work is to develop a non-linear numerical analysis of the seismic behavior of the Cathedral using the finite element method, with the aim of allowing the perpetuation of historical constructions. The seismic analysis was developed with geological database comprising seven natural accelerograms, with five return times (50, 75, 101, 201, and 475 years). This analysis entailed the detailed examination of the accelerations, tensions and deformations resulting from the application of seismic events in the Cathedral's structure and indicate the failure zones. The greatest accelerations were observed for the seismic event with a magnitude of 6.93 Mw, a return time of 475 years, and were indicative of the most fractures in the Dome region.

Tezcan S., Pando M.A., Aguilar R., Perucchio R.

Huaca de la Luna is a monumental earthen complex near Trujillo in north coastal Peru built from 200 AD to 850 AD by the Moche civilization. Its principal structure – a stepped pyramid built with millions of adobe bricks on sloping bedrock and soft soil – presents severe structural damage at the NW corner. The static and dynamic response of the pyramid is systematically analyzed using 2D and 3D nonlinear FE models derived from a detailed evaluation of archaeological, material, and geotechnical data. The analyses are performed in Abaqus/CAE Explicit using concrete-damaged plasticity and Mohr-Coulomb formulation for adobe construction and soft soils, respectively. The time-evolution of elastic strain and dissipative plastic energy is used to follow the development of local damage conditions up to structural collapse. A critical cross-sectional configuration is identified through 2D FE plane strain sensitivity analysis of the static and lateral capacity to (a) pyramid stepped west side profile, (b) underlying bedrock configuration, and (c) adobe tensile strength. 3D models derived from the 2D critical configuration are then evaluated in terms of static stability, lateral capacity, and failure mechanisms. Results indicate that horizontal accelerations produce large structural failure at the pyramid northwest corner similar in extent and location to the present damage.

Remus A.M., Yılmaz L., Tezcan S., Perucchio R.

The Moche civilization constructed the monumental adobe complex Huaca de la Luna in phases from 100–650 CE. Its main stepped pyramid is the focus of this study. Located at the foot of Cerro Blanco, near coastal Trujillo, Perú, the structure is subject to Pacific Ring of Fire seismic activity. Damage to the northwest corner and looting on the north and west façades have motivated structural analysis using nonlinear FE models that treat the base of the pyramid as directly attached to the underlying sloping bedrock and soft soil. The present work introduces the following factors to a 2D cross-section model: (a) an interposing sand layer of varying thickness between the adobe construction and the sloping bedrock of Cerro Blanco, (b) a frictional interaction at this interface, and (c) architectural additions to the main pyramid’s east side. Using a Design of Experiments (DOE) methodology, this study investigates how these factors affect the monument’s lateral capacity, measured through the time-evolution of strain and plastic dissipation energy. Results indicate that the interposing sand layer and construction on the east side influence the results the most. Consequently, further on-site survey should focus on a more accurate definition of these features. Simulations are performed in Abaqus/CAE Explicit using the concrete damaged plasticity and the Mohr-Coulomb formulations for modeling adobe and sand, respectively. Statistical analysis is performed in the statistical software JMP version 16, primarily focusing on Analysis of Variance (ANOVA).

Riccio C., Remus A., Tezcan S., Silva L.C., Milani G., Perucchio R.

This study contributes to the seismic structural failure analysis of the main pyramid of the archaeological complex Huaca de la Luna, Peru. Built with millions of adobe bricks by the Moche civilization (200–850C.E.), the monument is one of the largest adobe structures in the world. The monument shows signs of severe natural and anthropogenic damage due to its position along the Pacific Ring of Fire and extensive looting since Spanish colonial times. The pyramid was built as a succession of taller and larger platforms, each formed by erecting adjacent but disconnected vertical piers made of adobe masonry. A multiscale 2D nonlinear finite element (FE) model is introduced for assessing the contribution of this pier architecture to the structural response of the pyramid. The time-evolution of elastic strain and plastic dissipation energies is used to quantitatively track structural failure. The instant of structural collapse and attendant lateral capacity can be extracted from the point at which these energies match. Critical regions of a representative cross-section are modelled with individual piers represented by macroblocks and separated by frictional interfaces. A continuous description is adopted for the remaining part of the model. A nonlinear, two-dimensional (2D) plane strain analysis is conducted in Abaqus/CAE Explicit using concrete damaged plasticity and Mohr-Coulomb formulations for adobe construction and soft soil, respectively. A two-stage assessment procedure begins with a quasi-static analysis to predict the stress state due to gravitational load. A dynamic analysis follows to identify lateral capacity and failure mechanisms triggered by monotonically increasing ground acceleration. The development of local damage conditions up to structural collapse is visualized by the nucleation and propagation of maximum principal plastic strains throughout the model. A sensitivity analysis was conducted to evaluate the effect on lateral capacity of the contact friction coefficient between macroblocks and the number of macroblocks used to discretize the critical area. Introducing macroblocks to the model produces lateral capacities that are lower than analogous, purely-continuum models. These results are shown to be critically affected by the frictional coefficient that governs contact between the macroblocks. The results of this study offer critical insights on the consolidation strategy for the northwest corner of the pyramid and may find application to similarly-built historical earthen structures in northern Peru.

Rainone L.S., Tateo V., Casolo S., Uva G.

Considering the high vulnerability of existing masonry buildings, which often have strategic or cultural value, professionals and specialized engineers are frequently required to model complex historical buildings. The approaches proposed by National Building Codes may not always be suitable for such cases, but more detailed approaches are necessary, relying on FEM continuum modeling and inelastic constitutive law. There are many constitutive laws proposed in the literature that allow us to accurately reproduce the mechanical behavior of masonry. However, they require the identification of several parameters that are not easy to determine. In this study, a sensitivity analysis of the parameters of a nonlinear constitutive law very popular for masonry modeling (the “Concrete Damage Plasticity—CDP” model) is conducted, considering literature tests of masonry panels under shear stress as the benchmark. The aim is to assess the influence of the main parameters of the model and compare them to one of the more commonly used Mohr–Coulomb failure criteria.

Schiavoni M., Giordano E., Roscini F., Clementi F.

The structural assessment of ancient masonry structures is still a challenging task. The main reasons have been related to the shortage of information in the materials’ characterization along with the complex geometry and different evolutions of its constituents’ parts through the time. Scientific studies on the evaluation of the structural capacity and design of these masonry buildings have reported several modelling techniques. The goal of this work is to investigate the effectiveness of different numerical approaches in the simulation of the cyclic behaviour of historic masonry buildings under seismic loads. In addition, the damage level of the structural interconnections will be evaluated and what extent they affect the global instability. The specific case study seeks to examine an ancient palace with its civic tower hit by the 2016 Central Italy earthquake. A couple of masonry modelling are used: the first one is discontinuous (DM) and the second one is continuous (CM). Two models were set: one model replicated the structure as a whole, the other one considered only the tower. The DMs were studied with 3DEC© and LMGC90© software, where, in turn, different contact conditions were implemented. In parallel, the CMs were analysed with the Midas FEA NX©. The present research offers significant outcomes obtained from the non-linear dynamic analyses performed using the proper sequence recorded in that seismic event. Likewise, this document underlines the importance of the correct modelling techniques definition, based on the state of the case study, especially when an isolated tower is considered.

Nastri E., Tenore M., Todisco P.

The masonry buildings represent the largest portion of the Italian building heritage considering that about eighty percent of buildings is made of different kind of masonry. Italian cities are characterized by the presence of numerous masonry buildings of historical and architectural value. It is possible to find a large variety of building techniques and constructional material leading to different masonry structures that need to be precisely characterized as regards the mechanical behaviour. In this paper, the calibration of the materials parameter for an adequate modelling of typical tuff masonry constructive systems spread in Campania region is given. The calibration has been developed reproducing, by FEM analysis, real compression tests performed in displacement control available in literature. In particular, reference is made to masonry with regular ashlars, listed tuff masonry and chaotic tuff masonry. The FEM analyses have been carried out considering the “Concrete Damaged Plasticity” failure criteria. Moreover, the modelling of a wall subjected to horizontal actions has been investigated with reference to solid brick elements and shell to analyse if there is any shape factor affecting the different response. It can be pointed out that the analytical model used for the calibration of uniaxial tension and compression curves shows great adaptability and versatility for each type of masonry.

Ferretti F., Simoni E., Buratti N., Mazzotti C.

AbstractUnReinforced Masonry (URM) buildings constitute the majority of the Italian building stock and represent one of the most vulnerable construction typologies, as emerged during the seismic events occurred in the last decades. The objective of the present work is the proposal of a methodology for the seismic vulnerability and fragility assessment of different typologies of URM buildings. Through the statistical analysis of post-earthquake damage survey forms and of census data, the most prevalent structural typologies were identified in the Emilia Romagna region (Italy), leading to the definition of two reference masonry buildings, built at the beginning of the XX century and representative of the building stock of the study area. These buildings were modeled according to the equivalent frame method and their seismic performance was studied by means of nonlinear static analyses, considering uncertainties on the mechanical properties of masonry, on the intensity of the seismic action and on the displacement demand calculation method. Through the definition of Response Surfaces, analytical fragility curves relative to the investigated structural typologies were determined for the different damage states.

Misir I.S., Yucel G.

Failure under seismic action generally occurs in the form of out-of-plane collapses of walls before reaching their in-plane strength in historical stone masonry buildings. Consistent finite element (FE) macro modeling has emerged as a need for use in seismic assessments of these walls. This paper presents the numerical model calibration of U-shaped multi-leaf stone masonry wall specimens tested under ambient vibrations and out-of-plane (OOP) load reversals. The uncertain elastic parameters were obtained by manual calibration of the numerical models based on ambient vibration test (AVT) data of the specimens. To obtain nonlinear calibration parameters, static pushover analyses were performed on FE models simulating quasi-static tests. The calibrated numerical models matched well with the experimental results in terms of load–drift response and damage distribution. As a result, the modulus of elasticity and tensile and compressive degrading strength parameters of masonry walls were proposed. A parametric study was conducted to examine the effects of different materials and geometric properties (tensile strength, aspect ratio, slenderness ratio, and geometric scale) on the OOP behavior of stone masonry walls. A quite different strain distribution was obtained in the case of a large aspect ratio, while it was determined that the geometric scale had no effect on the strain distribution. Tensile strength was the dominant parameter affecting the load–drift response of the models. Within the presented work, a practical tool for out-of-plane seismic assessment has been proposed for the structures covered in this paper.

Gaggero M.B., Korswagen P.A., Esposito R., Rots J.G.

Innovative solutions for seismic-retrofitting existing structures are currently required, as often traditional strategies are expensive, non-reversible, highly invasive, and/or fail to address both serviceability and ultimate limit states together. The present paper describes a preliminary experimental campaign performed at TU Delft to investigate an innovative structural glass window for strengthening masonry buildings. To this purpose, a prototype composed of a timber frame, a semi-rigid adhesive, and a 20 mm thick structural glazing layer was designed. The prototype aimed to improve the structure’s behavior against minor but more frequent service vibrations (SLS), as well as against ultimate ones (ULS). Specifically, an increase in the structure’s in-plane capacity and stiffness was targeted to reduce cracking at low drifts/displacements, while at larger drifts, the adhesive’s tearing and timber crushing were used to activate damping. To evaluate the prototype’s performance, a quasi-static, cyclic, in-plane test on a strengthened full-scale wall was performed and compared with available data on a similar, yet unstrengthened, wall. Although the benefits were not pronounced in terms of cracking and energy dissipation, the implementation of the proposed strategy provided an increase in terms of initial stiffness (18%), force capacity (8%, 36%), and ductility (220%, 135%). This outcome provides the ground for numerical studies that will help better delineate the proposed strategy and improve the current design.

Schiavoni M., Giordano E., Roscini F., Clementi F.

The conservation of the historical and artistic heritage is one of the main priorities of Italian and international policy. The great variety of masonry buildings that make up this heritage is characterized by different combinations of materials and construction techniques. Then, several damage scenarios could be observed as a result, requiring appropriate retrofitting interventions. A rather accurate structural behavior analysis, especially for horizontal load conditions, allows for elaborating a correct seismic assessment. Albeit there are various numerical tools available to examine them, each one’s process starts by means of certain assumptions that could not be applied indiscriminately. This paper aims to compare two different types of modeling techniques to evaluate their strengths and weaknesses. To achieve this goal, an earthquake-damaged complex in Central Italy was chosen as a case study. The structure was modeled using a finite element (continuous) and a distinct element (discontinuous) method. Both approaches underwent a nonlinear dynamic analysis using the strong motions recorded during the 2016 seismic sequence. The results show that both approaches can evaluate the weak structural points. However, in some cases, the distinct element method appeared more accurate in reproducing the cracks.

Orlando M., Becattini G., Betti M.

The paper deals with the structural analysis and strengthening design of a masonry fortress, named “Rocca Ariostesca”, located in Castelnuovo Garfagnana, Italy, through the combination of visual/empirical, experimental, and numerical methods. The work was developed within a project aimed at the rehabilitation of the fortress. The project involves the creation of a new museum dedicated to the famous poet Ludovico Ariosto and the Garfagnana region in the sixteenth century. The paper illustrates the evaluation of the conservation state of the building, the analysis of its static and seismic behaviour, and the strengthening design. The first part describes the activities carried out to acquire a suitable knowledge of the structure, which is of fundamental importance to choose the most appropriate analysis strategies and structural strengthening works. The information acquired in the knowledge phase is also important to choose the modelling scale to evaluate the static and dynamic behaviour of the building. The second part of the paper deals with the structural check of the masonry walls and wooden floors for both gravitational and seismic loads. The last part of the paper presents the strengthening design of the building, aimed at increasing the structural capacity to both vertical and seismic loads. The paper highlights how a multi-method approach, through the combination of visual/empirical methods and finite element numerical models, calibrated and validated on experimental data, allow for an efficient and reliable structural evaluation of existing historical masonry buildings and for the design of the structural strengthening. The multi-method approach allows for reducing the uncertainties in the evaluation of the structural safety of the building and to better define its structural rehabilitation and seismic retrofitting. • Knowledge process for a masonry fortress through geometric survey, in-situ tests, and load testing on floors. • Creation of a 3D F.E. model for global static analysis and modal analysis and of a 3D macro-element model for identification of local failure mechanisms. • Seismic capacity of the building mainly controlled by local collapse mechanisms. • Design of non-invasive retrofitting works to solve structural deficiencies respecting the monumental building conservation state.

Bayraktar A., Hökelekli E., Yang T.T.

• Static and seismic behaviours of masonry domes with circular drum, with circular drum and buttress, with octagonal drum, and with octagonal drum and buttress. • Failure behaviours of masonry domes (a dome with circular drum, a dome with circular drum and buttress, a dome with octagonal drum, a dome with octagonal drum and buttress) under strong earthquake shaking. • Failure angles of masonry domes (a dome with circular drum, a dome with circular drum and buttress, a dome with octagonal drum, a dome with octagonal drum and buttress) with thickness-to-span ratios t/R=0.092 under strong ground motions. General stability and failure behaviors of masonry domes under static loads have been investigated extensively in literature. However, a few studies have been done on the seismic failure behavior of masonry domes under strong ground shaking. This study aims to investigate the seismic failure behaviors and failure angles of masonry domes with support system including drum and buttresses using advanced 3D nonlinear numerical simulations. Four types of masonry domes with thickness-to-span ratios t/R=0.092, such as a dome with circular drum (Dome A), a dome with circular drum and buttress (Dome B), a dome with dodecagon drum (Dome C), a dome with dodecagon drum and buttress (Dome D), built on historical structures are selected. Three-dimensional solid finite element models of the selected masonry domes are created using isotropic continuum macro modelling technique with homogenized properties. The finite element models are utilized to simulate the seismic behaviors of the masonry domes under three different strong ground motion acceleration records matched according to the target response spectrum with a return period of 475 years in the Turkish Building Earthquake Code. The seismic failure behaviors of four masonry dome models are evaluated by comparing mode shapes, displacements, maximum principal stresses, damage propagation patterns and failure angles. It is determined that the average angle intervals of hoop tension failure regions of Dome A, Dome B, Dome C and Dome D models under strong ground motions vary between 39, 25, 35 and 26 degrees, respectively.

Preciado A., Peña F., Colmenero Fonseca F., Silva C.

• Observed damages during post-earthquake investigations on Colonial Churches. • Damage identification and failure propagation on different masonry elements. • Schematic representation of cracks/failure patterns in several structural elements. • Crack propagation in arches, vaults, domes, bell towers, belfries and façades. • Valuable insights to propose suitable rehabilitation and retrofitting works. This paper aims to describe the observed damage and crack propagation in patrimonial masonry buildings of Puebla and Morelos, Mexico due to both September 7 (M w = 8.2) and 19 (M w = 7.1) 2017 earthquakes. Historical masonry buildings are earthquake prone structures due to the missing structural integrity by the low tensile strength of masonry, heavy inertial forces, large openings and structural elements with different in-plane and out-of-plane behavior, especially when detached from the rest of the building. The two large seismic events damaged 2340 architectural heritage buildings, mainly in the States of Puebla, Morelos and Mexico. The observed damages during post-earthquake investigations ranged from moderate to heavy, with partial and total collapses, mainly in vaulted systems and bell towers. The presented damage identification and failure propagation description allowed to generate practical schematic representations of crack patterns in several structural elements such as domes, vaulted covers, façades, bell towers and so on, providing valuable information that can be useful to propose suitable rehabilitation and retrofitting works. The 2017 earthquakes also generated uncountable damages in different cultural assets including retables, painted murals and bells, being of great cultural and historical value. The main causes of the observed damages in masonry structures are also due to the lack of maintenance, previous structural modifications and inadequate interventions. Continuous and correct maintenance of structures is indispensable to reduce the possible damages due to earthquakes. Thus, a detailed structural assessment of the buildings is always necessary to carry out an adequate intervention according to the criteria of restoration.