Nonlinear Behavior Of Masonry Research Articles

Seismic performance of a masonry house prototype retrofitted using frp strip: a numerical study

This study presents a series of finite element analyses on the prototype of masonry house retrofitted using FRP strips . The model of the masonry house refers to the prototype scaled to 1:3 tested in an experimental campaign. The non-linear behavior of masonry is modeled through the Concrete Damage Plasticity (CDP) model, while the FRP and adhesive are modeled as two separated isotropic solid materials with elastic-plastic behavior. A good agreement between experimental and numerical result is obtained, indicating the increase of bearing capacity of the reinforced masonry prototype.

Out-of-plane response of ECC-strengthened masonry walls

ABSTRACTThis paper focuses on the flexural behavior of masonry walls strengthened with precast engineered cementitious composite (ECC) sheet. The walls were subjected to out-of-plane static loading and analyzed using ABAQUS. For the validation of numerical results, four masonry walls of size 762 × 480 × 230 mm were cast using burnt clay bricks and cement mortar. Out of four, two masonry walls were strengthened with precast ECC sheet using epoxy as adhesive, and the remaining two acted as control specimens. The validation of numerical results with the experimental results shows that the model can effectively capture the nonlinear behavior of masonry and ECC to predict the strength and failure mechanism. The influence of mesh size on the numerical results is also reported. Further, a parametric study has been carried out to observe the effect of several parameters such as percentage of ECC reinforcement ratio, span/depth (L/d) ratio and width/thickness (b/h) ratio of the strengthened masonry walls. This study reveals that the precast ECC sheet increases the load-carrying capacity and ductility of brick masonry walls and hence demonstrates its performance as a strengthening element for brick masonry structures.

Engineering simulations of a super-complex cultural heritage building: Ica Cathedral in Peru

The Cathedral of Ica, Peru, is one of the four prototype buildings involved in the ongoing Seismic Retrofitting Project, initiative of the Getty Conservation Institute. The complex historical building, which was heavily damaged by earthquakes in 2007 and 2009, can be divided into two substructures: an external masonry envelope and an internal timber frame built by a construction method known as quincha technique. This study makes use of the information available in literature and the results obtained from experimental campaigns performed by Pontificia Universidad Catolica del Peru and University of Minho. Nonlinear behaviour of masonry is simulated in the numerical models by considering specified compressive and tensile softening behaviour, while isotropic homogeneous and linear behaviour is adopted for modelling timber with appropriate assumptions on the connections. A single representative bay was initially studied by performing linear elastic analysis and verifying the compliance with the various criteria specified by the applicable normative to discuss the actual failure of Ica Cathedral. Afterwards, the structural behaviour of the two substructures composing the Cathedral is evaluated independently. Finally, the interaction of these two substructures is investigated by performing structural analysis on the entire structure of Ica Cathedral. Several structural analysis techniques, including eigenvalue, nonlinear static and dynamic analyses, are performed in order to: (1) evaluate the dominant mode shapes of the structure; (2) validate the numerical models by reproducing the structural damage observed in situ; (3) estimate the structural performance; and (4) identify the main failure mechanisms.

Seismic Assessment of a Monumental Building through Nonlinear Analyses of a 3D Solid Model

ABSTRACTThe paper analyzes the static behavior and the seismic vulnerability of the “San Francesco ad Alto” building in Ancona (Italy), which is currently used as a Regional Headquarter of the Marche Region by the Italian Army and was formerly a monastery. The global static structural behavior and the dynamic properties have been evaluated using the Finite Element modeling technique, in which the nonlinear behavior of masonry has been taken into account by proper constitutive laws. The concepts of homogenized material and smeared cracking are used to evaluate the capacity of the monastery to withstand lateral loads together with the expected demands resulting from seismic actions (N2 method), using a nonlinear static analysis (pushover). The comparison of seismic demand and capacity confirms the susceptibility of these types of buildings to extensive damage and collapse, as frequently observed in similar buildings. This paper aims to point out that advanced numerical analyses can offer significant information on the understanding of the actual structural behavior of historical buildings. It is believed that the methodology and the overall conclusions of this case study are valid for many historical monasteries in Europe.

Assessment of seismic behaviour of heritage masonry buildings using numerical modelling

The paper analyzes the seismic vulnerability of the historical complex of “San Francesco” located in Cagli, Marche Region, Italy. It provides both advanced 3D modelling with solid elements and equivalent frame modelling. The building is composed of a church and a monastery used as a lower secondary school, and preservation and maintenance of its structural efficiency are of primary importance. The global structural behaviour and dynamic properties of the compound have been evaluated using the Finite Element Modelling (FEM) technique, where the nonlinear behaviour of masonry has been taken into account by proper constitutive assumptions. A sensitivity analysis is done to evaluate the effect of the choice of the control point on the value of seismic risk index, by varying the stiffness of the floors and the effects of different knowledge levels. The aim of the paper is to emphasize the importance of thorough knowledge of historic buildings in order to understand the real seismic behaviour of a structure, to detect common vulnerability of this type of building, the knowledge of which is necessary to design restorations aimed at improving the seismic behaviour of masonry buildings. Some comparisons with the Equivalent Frame Method (EFM) are also presented.

Damage Functions for the Vulnerability Assessment of Masonry Buildings Subjected to Tunneling

This paper describes a new framework for the assessment of potential damage caused by tunneling-induced settlement to surface masonry buildings. Finite element models in two and three dimensions, validated through comparison with experimental results and field observations, are used to investigate the main factors governing the structural response to settlement. Parametric analyses are performed on the effect of geometrical and structural features, like the building dimensions, the nonlinear behavior of masonry, and soil-structure interactions. These results are used to create a framework of an overall damage model that correlates the analyzed parameters with the risk of the building being damaged by a given level of settlement. The proposed vulnerability framework has the potential to be developed as a decision and management tool for the evaluation of the risk associated with underground excavations in urban areas.

An efficient Bouc & Wen approach for seismic analysis of masonry tower

The assessment of existing masonry towers under exceptional loads, such as earthquake loads, requires reliable, expedite and efficient methods of analysis. These approaches should take into account both the randomness that affects the masonry properties (in some cases also the distribution of the elastic parameters) and, of course, the nonlinear behavior of masonry. Considering the need of simplified but effective methods to assess the seismic response of such structures, the paper proposes an efficient approach for seismic assessment of masonry towers assuming the material properties as a stochastic field. As a prototype of masonry towers a cantilever beam is analyzed assuming that the first modal shape governs the structural motion. With this hypothesis a nonlinear hysteretic Bouc & Wen model is employed to reproduce the system response which is subsequently employed to evaluate the response bounds. The results of the simplified approach are compared with the results of a finite element model to show the effectiveness of the method.

Seismic capacity evaluation of unreinforced masonry residential buildings in Albania

Abstract. This study evaluates seismic capacity of the unreinforced masonry buildings with the selected template designs constructed per pre-modern code in Albania considering nonlinear behaviour of masonry. Three residential buildings with template designs were selected to represent an important percentage of residential buildings in medium-size cities located in seismic regions of Albania. Selection of template designed buildings and material properties were based on archive and site survey in several cities of Albania. Capacity curves of investigated buildings were determined by pushover analyses conducted in two principal directions. The seismic performances of these buildings have been determined for various earthquake levels. Seismic capacity evaluation was carried out in accordance with FEMA (Federal Emergency Management Agency) 440 guidelines. Reasons for building damages in past earthquakes are examined using the results of capacity assessment of investigated buildings. It is concluded that of the residential buildings with the template design, with the exception of one, are far from satisfying required performance criteria. Furthermore, deficiencies and possible solutions to improve the capacity of investigated buildings are discussed.

Seismic Assessment of St James Church by Means of Pushover Analysis – Before and After the New Zealand Earthquake

The paper presents a numerical study for the seismic assessment of the St James Church in Christchurch, New Zealand affected by the recent 2011 earthquake and subsequent aftershocks. The structural behavior of the Church has been evaluated using the finite element modelling technique, in which the nonlinear behavior of masonry has been taken into account by proper constitutive assumptions. Two numerical models were constructed, one incorporating the existing structural damage and the other considering the intact structure. The validation of the numerical models was achieved by the calibration of the damaged model according to dynamic identification tests carried out in situ after the earthquake. Non-linear pushover analyses were carried out on both principal directions demonstrating that, as a result of the seismic action, the Church can no longer be considered safe. Pushover analysis results of the undamaged model show reasonable agreement with the visual inspection performed in situ, which further validates the model used. Finally, limit analysis us-ing macro-block analysis was also carried out to validate the main local collapse mechanisms of the Church.

Numerical assessment of the static and seismic behaviour of the basilica of Santa Maria all’Impruneta (Italy)

The paper analyses the static behaviour and the seismic vulnerability of the Basilica of Santa Maria all’Impruneta near Florence (Italy). The static structural behaviour and the dynamic properties of the church have been evaluated using the finite element modelling technique, where the nonlinear behaviour of masonry has been taken into account by proper constitutive assumptions. A macro-modelling approach has been used based on the concepts of homogenisated material and smeared cracking and crushing constitutive law. Seismic vulnerability has been evaluated using a pushover method, and the results obtained with the nonlinear numerical model have been compared with the simplified schemes of limit analysis. The capacity of the church to withstand lateral loads is evaluated together with the expected demands resulting from seismic actions. The comparison of seismic demand vs. capacity confirms the susceptibility of this type of buildings to extensive damage and collapse, as frequently observed in similar buildings. The paper’s aim was to point out that advanced numerical analyses can offer significant information on the understanding of the actual structural behaviour of historic buildings. The methodology and the conclusions of this case study it is believed that are applicable to a wide variety of historic Basilica churches.

Analysis and modelling of the in-plane shear behaviour of hollow brick masonry panels

The paper presents a numerical and an experimental analysis of the in-plane shear behaviour of hollow brick masonry panels. The non-linear behaviour of masonry is modeled considering elastic-perfectly plastic behaviour of the mortar joint. Experimental methodology consists in the diagonal compression of considered masonry walls. Numerical and experimental results are compared and discussed. The efficiency of modelling to forecast a representative failure mode of the masonry is investigated.

Typical masonry failures and repairs: a German Engineer's view

AbstractMasonry is one of the oldest or maybe the oldest building material of all. Starting with a very short historical review, the paper gives some remarks on the basic mechanical and material behaviour of the discontinuous, nonlinear behaviour of masonry as a jointed block structure. It is important to keep in mind that there is a big difference in masonry on different sides of the Atlantic.Basic principles and statements dealing with the compressive (uniaxial, biaxial) and shear strength are derived. Typical failures and repairs are discussed. Taking into account the complex structure and the large variety with respect to block sizes, block qualities, mortars, bond forces and the overall geometry, the designer is forced to use alternative modelling techniques to the finite element method (FEM).One alternative is the distinct element method (DEM), which allows large rotations of the blocks and large deformations, e.g. separations in and of the joints. This method is well established for analysing rock masses, but, as is demonstrated in this paper, it is also well suited to investigate masonry failure mechanisms. The discontinuous non‐homogeneous behaviour of masonry can be modelled very well, and the results can be favourably compared with real cracking behaviour.

Basic behaviour of masonry: Case studies, alternative approaches and modelling hints

Masonry is one of the oldest building materials, but there are many unsolved problems regarding the basic strength and deformation behaviour. The paper focuses on the different masonry qualities both in Europe and the USA by comparing the discontinuous, non-linear behaviour of masonry as a jointed block structure with other building materials, e.g. rock mass. Basic principles and statements dealing with the compressive (uniaxial, biaxial) and shear strength are derived. Taking into account the complex structure and the large variety with respect to block sizes, block qualities, mortars, bond forces and the overall geometry the designer is obliged to use alternative modelling techniques to the finite element method (FEM). One alternative is the distinct element method (DEM), which allows large rotations of the blocks and large deformations, e.g. separations in and of the joints. This method is well established for analysing rock masses but, as demonstrated in this paper, it is well suited also to the inves...