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1.
Enzo Martinelli Francesco Perri Carmen Sguazzo Ciro Faella 《Bulletin of Earthquake Engineering》2016,14(6):1695-1720
This work reports the results of an experimental programme aimed at investigating the in-plane behaviour of clay-brick masonry walls externally strengthened by carbon fiber reinforced polymer (CFRP) strips. Particularly, four different geometrical layouts were considered for the CFRP strips, though keeping unchanged the quantity of composites employed in each wall. Firstly, a preliminary experimental work was carried out on samples of the constitutive materials for quantifying their key mechanical properties and evaluating the bond behaviour of FRP strips on the masonry substrates. Then, eleven cyclic shear-compression tests were performed to observe the response of strengthened walls and the influence of the strengthening layouts under investigation. The proposed experimental report is intended as a contribution to the current state of knowledge about the behaviour of FRP-strengthened masonry walls: it is available to assess the accuracy and possibly improve the predictive capacity of design-oriented capacity models. Finally, the comparison of the reported experimental results with the predictions obtained by applying the analytical relationships proposed by a recently issued guideline for FRP strengthening of masonry structures is proposed. 相似文献
2.
The evaluation of the dynamic behaviour of rocking elements is directly correlated to the energy dissipated because of the impacts at the base interface, which can be represented by means of a coefficient of restitution. This schematization is commonly accepted as representative of the out‐of‐plane response of stone masonry walls. An experimental campaign (in a lab environment) aiming at assessing the value of this coefficient for a sacco granite masonry wall is presented in this work. The rocking motion at a predefined bed joint level was induced in the tested specimens in order to validate a novel test setup designed to assess the coefficient of restitution value by means of a realistic reproduction of the rocking behaviour of a single element, under the hypothesis of an infinitely stiff system above the bed joint level. As the main objective of the work was to assess the rocking behaviour of a masonry wall that looses energy at the impacts at a certain joint level, the flexural behaviour was not desirable and had to be avoided. For this purpose, a test setup based on the equivalent block approach was developed. In the final section of this work, comparisons between experimental and numerical results are presented together with some preliminary conclusions on the appropriate modelling strategy and the values of the coefficient of restitution to be used for the seismic assessment of the out‐of‐plane rocking behaviour of this type of sacco stone masonry walls. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
3.
Fabio Mazza 《地震工程与结构动力学》2019,48(4):432-453
The out-of-plane (OOP) behaviour of masonry infills (MIs), inserted in reinforced concrete (r.c.)–framed buildings, is recognized as one of the most important failure modes of this nonstructural element during an earthquake, which may be a consequence of simultaneous or prior in-plane (IP) damage. A five-element macro-model, with four diagonal OOP non-linear beams and one horizontal IP non-linear truss, with an equivalent mass of the infill panel divided between two central nodes, takes into account the IP and OOP failure modes occurring in the event of seismic loading. Pivot hysteretic models predict the non-linear IP and OOP force-displacement laws of the infill panel, based on geometrical rules defining loading and unloading branches. Firstly, a calibration of the proposed IP-OOP interaction model of MIs is carried out considering full-scale experimental results of traditional masonry typologies. Each specimen is initially subjected to in-plane quasi-static cyclic loading, until a maximum drift is reached, and then one-sided OOP cycles are imposed pushing in the horizontal direction and back to zero force. Then a numerical investigation considers masonry infills of an existing six-storey r.c.-framed building designed in compliance with a former Italian seismic code. To evaluate the interaction, the results of simultaneous IP and OOP cyclic tests on MIs at the top, intermediate, and lowest levels of the test structure are presented, assuming different displacement histories: (1) OOP loading faster than IP, at the sixth storey; (2) equal IP and OOP loading, at the third storey; (3) IP loading faster than OOP, at the first storey. Finally, attention is focused on the contribution of masonry infills to the IP and OOP energy dissipation of r.c.-framed structures. 相似文献
4.
Alexandre A. Costa António Arêde Aníbal Costa Carlos Sousa Oliveira 《Bulletin of Earthquake Engineering》2012,10(1):93-111
Masonry structures can be considered as the simplest type of structures concerning its assemblage but, at the same time, it
is one of the most complex construction materials in terms of mechanical properties and correct behaviour assessment. In this
context, the work herein presented aims at describing an experimental testing campaign recently carried out in order to characterize
the out-of-plane behaviour of traditional masonry constructions. Taking advantage of the existence of a traditional two-storey
masonry building abandoned after the 1998 Azores earthquake, several in-situ tests were defined and performed with the application
of quasi-static cyclic loads at the building top level in the out-of-plane direction. In addition, the efficiency of retrofitting
and/or strengthening techniques applied during the 1998 Azores reconstruction process was also experimentally evaluated. Finally,
an overall discussion of these techniques is presented, resorting also to previous tests’ results carried out by the same
authors, aiming at inferring and suggesting quantifications of strengthening techniques’ contributions for future interventions
on existing buildings. For this purpose, simple analytical mechanical approaches were adopted in order to provide numerical
estimates of strength that were found in good agreement with the experimental results. 相似文献
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6.
Umberto Tomassetti António A. Correia Francesco Graziotti Andrea Penna 《地震工程与结构动力学》2019,48(11):1297-1318
Typical low-rise masonry buildings consist of unreinforced masonry (URM) walls covered with various timber roof configurations generally supported or finished by masonry gables. Post-earthquake observations and experimental outcomes highlighted the large vulnerability of the URM gables to the development of overturning mechanisms, both because of the inertial out-of-plane excitation and the in-plane timber diaphragm deformability. This paper presents the static and dynamic experimental seismic performance of three full-scale roofs tested via quasi-static cyclic and shake table tests. Two of them were tested as part of a whole full scale one-storey and two-storey building. A single-degree-of-freedom (SDOF) numerical model is calibrated against experimental data and proposed for the analysis of this roof typology's dynamic behaviour. Several sets of analyses were conducted to assess the vulnerability of these structural components and to study the effect of the whole building's characteristics (eg, number of storeys and structural stiffness and strength) on the seismic performance of this roof typology. 相似文献
7.
The evaluation of the out‐of‐plane behaviour of unreinforced walls is one of the most debated topics in the seismic assessment of existing masonry buildings. The discontinuous nature of masonry and its interaction with the remainder of the building make the dynamic modelling of out‐of‐plane response troublesome. In this paper, the results of a shaking table laboratory campaign on a tuff masonry, natural scale, U‐shaped assemblage (façade adjacent to transverse walls) are presented. The tests, excited by scaled natural accelerograms, replicate the behaviour of external walls in existing masonry buildings, from the beginning of rocking motion to overturning. Two approaches have been developed for modelling the out‐of‐plane seismic behaviour: the discrete element method and an SDOF analytic model. Both approaches are shown to be capable of reproducing the experimental behaviour in terms of maximum rotation and time history dynamic response. Finally, test results and numerical time history simulations have been compared with the Italian seismic code assessment procedures. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
8.
The three-dimensional non-linear earthquake behaviour of unreinforced masonry buildings is studied by using a constitutive model established experimentally for burned-clay brick masonry wall panels. The parameter functions appearing in the constitutive model are modified so that they accommodate a wall panel made of a general masonry material. In the study it is assumed that the floors of the masonry building are reinforced concrete slabs which are infinitely rigid in their own planes and that the wall panels possess only in-plane rigidities. Some examples involving earthquake analyses of two different masonry structures are presented. It is found that the predictions of the model used in the study are in harmony with the experimental data available in the literature. 相似文献
9.
Displacement capacity of masonry piers: parametric numerical analyses versus international building codes 总被引：1，自引：1，他引：0
Maurizio Orlando Luca Salvatori Paolo Spinelli Mario De Stefano 《Bulletin of Earthquake Engineering》2016,14(8):2259-2271
The nonlinear behaviour of masonry piers loaded in their plane is investigated by parametric numerical simulations. Each pier has a cantilever scheme, is loaded by a constant axial load and is subjected to an increasing horizontal displacement at the top. The macro-modelling approach is used to perform numerical analyses, adopting two different constitutive laws: a total strain crack model and a plastic model. The numerical model is calibrated on a block-masonry type for which experimental tests are available in literature. Parametric numerical simulations are performed by varying the aspect-ratio and the compression level, in order to assess the influence of such parameters on both shear strength and displacement capacity. By comparing numerical results with formulas of international codes, a good agreement for the shear strength is obtained, while significant differences are observed for the displacement capacity, which is influenced by both parameters. The authors propose a simple empirical formula for the displacement capacity, obtained by fitting the numerical results. The expression can be useful in the practical design for considering the influence of aspect-ratio and compression level, currently neglected by building codes. 相似文献
10.
Jorge Proen?a António Sousa Gago Joaquim Cardoso Vítor Cóias Raquel Paula 《Bulletin of Earthquake Engineering》2012,10(1):113-133
Traditional non-reinforced masonry walls are particularly prone to failure when subjected to out-of-plane loads and displacements
caused by earthquakes. Moreover, singularities such as openings in fa?ades may trigger local collapse, for either in-plane
or out-of plane motion. Bearing in mind all the former limitations, STAP, with the scientific support of ICIST and LNEC, has
been developing a reduced intrusiveness seismic strengthening methodology for traditional masonry structures. The technique
consists in externally applying Glass Fibre Reinforced Polymer (GFRP) composite strips to one or both faces of walls. Connection
between GFRP composite strips and masonry substrate is enhanced through specifically detailed anchorages or confinement connectors.
This technique has been developed and studied through an extensive series of experimental tests, which are briefly reviewed.
This paper focuses more deeply on the latest experimental program, aimed at the characterization of the masonry-GFRP composite
interface behaviour. This testing program comprised 29 masonry specimens, strengthened with externally bonded GFRP composite
strips with anchorages. The testing variables were the number and spacing of anchorages as well as the loading history type:
monotonic or repeated. Results clearly show that the use of anchorages dramatically enhances bond behaviour and that its number
and spacing have a significant effect on deformation capacity and a less pronounced effect on strength. Based on experimental
evidence, this paper also provides a calculation model and ULS safety assessment procedure for out-of-plane strength of reinforced
masonry walls. This calculation model leads to interaction curves on strengthened masonry walls subjected to compression and
out-of-plane flexure. 相似文献
11.
The determination of displacement demands for masonry buildings subjected to seismic action is a key issue in the performance-based assessment and design of such structures. A technique for the definition of single-degree-of-freedom (SDOF) nonlinear systems that approximates the global behaviour of multi-degree-of-freedom (MDOF) 3D structural models has been developed in order to provide useful information on the dependency of displacement demand on different seismic intensity measures. The definition of SDOF system properties is based on the dynamic equivalence of the elastic properties (vibration period and viscous damping) and on the comparability with nonlinear hysteretic behaviour obtained by cyclic pushover analysis on MDOF models. The MDOF systems are based on a nonlinear macroelement model that is able to reproduce the in-plane shear and flexural cyclic behaviour of pier and spandrel elements. For the complete MDOF models an equivalent frame modelling technique was used. The equivalent SDOF system was modelled using a suitable nonlinear spring comprised of two macroelements in parallel. This allows for a simple calibration of the hysteretic response of the SDOF by suitably proportioning the contributions of flexure-dominated and shear-dominated responses. The comparison of results in terms of maximum displacements obtained for the SDOF and MDOF systems demonstrates the feasibility and reliability of the proposed approach. The comparisons between MDOF and equivalent SDOF systems, carried out for several building prototypes, were based on the results of time-history analyses performed with a large database of natural records covering a wide range of magnitude, distance and local soil conditions. The use of unscaled natural accelerograms allowed the displacement demand to be expressed as a function of different ground motion parameters allowing for the study of their relative influence on the displacement demand for masonry structures. 相似文献
12.
A non-linear finite element model for plain masonry structures under lateral static loads and seismic base inputs is presented. Three super-imposed elasto-plastic shear elements are used in order to approximate the typical force-displacement curve for masonry. Material properties are identified with respect to results of shear tests on single piers. Modelling of entire structures is then performed and the numerical results are satisfactorily checked against the experimental outputs of static and shaking table tests of simple 1 and 2 storey buildings. The out of plane behaviour of walls is accounted for by means of a simplified method. 相似文献
13.
The in-plane capacity of unreinforced masonry (URM) elements may vary considerably depending on several factors, including boundary conditions, aspect ratio, vertical overburden, and masonry texture. Since the overall system resistance mainly relies on the in-plane lateral capacity of URM components when out-of-plane modes are adequately prevented, the structural assessment of URM structures could benefit from advanced numerical approaches able to account for these factors simultaneously. This paper aims at enhancing and optimising the employment of the distinct element method, currently confined to the analysis of local mechanisms of reduced-scale dry-joint blocky assemblies, with a view to simulate the experimentally observed responses of a series of URM full-scale specimens with mortared joints subjected to quasi-static in-plane cyclic loading. To this end, a mesoscale modelling approach is proposed that employs a simplified microscale modelling approach to effectively capture macroscale behaviour. Dynamic relaxation schemes are employed, in combination with time, size, and mass-scaling procedures, to decrease computational demand. A new methodology for numerically describing both unit, mortar and hybrid failure modes, also including masonry crushing due to high-compression stresses, is proposed. Empirical and homogenisation formulae for inferring the elastic properties of interface between elements are also verified, enabling the proposed approach to be applied more broadly. Using this modelling strategy, the interaction between stiffness degradation and energy dissipation rate was accounted for numerically. Although the models marginally underestimate the energy dissipation in the case of slender piers, a good agreement was obtained in terms of lateral strength, hysteretic response, and crack pattern. 相似文献
14.
等效框架模型采用宏观模型来模拟砌体墙在平面内的抗震性能。砌体墙的墙柱和墙梁采用同时考虑轴向弯曲和剪切变形的基于力法的纤维截面进行模拟,且两者的连接视为刚性区域。轴向压缩及弯曲效应在截面纤维模型中考虑,而剪切效应由V-γ剪切恢复力模型表达,弯曲和剪切在单元层面进行耦合。通过统计和分析,确定骨架曲线的计算方法,并基于Ibarra-Krawinkler模型提出剪切恢复力模型。通过算例得出:该模型在单调加载和循环加载下的数值计算结果与试验结果均吻合较好。 相似文献
15.
Shaking table tests on a full-scale unreinforced and IMG-retrofitted clay brick masonry barrel vault
The recent earthquakes in Italy demonstrated the extreme vulnerability of historical and cultural structures. Masonry vaults, which represent artistically valuable elements of these constructions, have been recognised among the most vulnerable elements. Traditional vault retrofit methods, such as buttresses or ties, are still widely adopted. These retrofit methods prevent differential displacements between vault supports (e.g., abutments, masonry piers and loadbearing walls). However, the pier differential displacement is not the only vulnerability source for vaults, and in many cases, further retrofit interventions are needed. Innovative retrofit methods based on inorganic matrixes, such as IMG, are aimed to prevent hinge mechanism failures. Such methods are suitable to be applied on vaults already retrofitted using traditional methods. The knowledge of the seismic behaviour of a vault, once the differential displacement between the supports is prevented, can be crucial to the assessment of potential further vulnerabilities of vaults already retrofitted with traditional methods. However, a deep knowledge of vault seismic behaviour is still lacking from an experimental point of view. Indeed, to date, few dynamic experimental studies have been conducted. Therefore, to investigate the seismic behaviour of masonry barrel vaults, several shaking table tests were performed on a full-scale specimen before and after the retrofit interventions. The tests investigated the main seismic properties of the tested structure and clarified the cracking mechanisms and capacity improvement due to the retrofit interventions. A comprehensive overview of the main results of the experimental tests has been presented. 相似文献
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18.
Bruno Silva Jo?o M. Guedes António Arêde Aníbal Costa 《Bulletin of Earthquake Engineering》2012,10(1):211-234
The conservation and rehabilitation of monuments is a matter of important investigation, and the need for accurate structural
analysis, capable of effectively predicting the structural behaviour of this type of constructions, under static and dynamic
loads, is increasing. Currently there are numerous computational methods and tools, supported by different theories and strategies
with different levels of complexity, computation time and cost which are available to perform such analyses. A complex analysis
is not always synonym of a better result and the choice of a method over another depends mostly on the purpose of the analysis.
This work aims at evaluating the capacity of a non linear continuum damage model (Faria et al. in Int J Solids Struct 35(14):1533–1558,
1998), originally developed for concrete structures, to simulate the behaviour of stone masonry structures. In particular, the
seismic response of an old stone masonry construction, the Gondar church, is analysed considering different levels of geometrical
and material complexity. The verification and calibration procedures use the experimental results from tests performed on
stone masonry walls at the Laboratory for Earthquake and Structural Engineering of the Faculty of Engineering of Porto University
and from other tests found in the bibliography (Vasconcelos in Experimental investigations on the mechanics of stone masonry:
Characterization of granites and behaviour of ancient masonry shear walls. PhD Thesis, Universidade do Minho, Guimar?es, Portugal,
2005). The results are compared, assessing the differences and the importance of using complex tools, such as the continuum damage
model, to better simulate and understand the global behaviour of such constructions. 相似文献
19.
This paper deals with the results of cyclic load tests on masonry walls performed for the purpose of evaluation of in-plane shear behaviour and identification of shear strength, stiffness and energy dissipation. Eight walls in two series were assembled in laboratory conditions. The first series consisted of four unreinforced masonry walls constructed from solid clay bricks and lime mortar. The walls from the second series were strengthened by application of RC jackets on both sides. These were constructed of the same material and were characterized by the same geometry properties and vertical load levels as those of the walls from the first series. The main goal of the tests was to compare the behaviour of the unreinforced and strengthened walls under cyclic horizontal load. The results from the tests showed that the application of the strengthening method contributed to a significant improvement of the shear resistance of the jacketed walls. Analytical models were used to predict the shear resistance of the walls. Good agreement with the experimental results was obtained with a model based on tensile strength of masonry. 相似文献
20.
This study focuses on the evaluation of seismic safety of unreinforced masonry buildings in Turkey by using fragility curves generated for two behavior modes of load bearing walls: in-plane and out-of-plane. During generation of fragility curves, a force-based approach has been used. There exist two limit states in terms of base shear strength for in-plane behavior mode and flexural strength for out-of-plane behavior mode. To assess the seismic vulnerability of unreinforced masonry buildings in Turkey, fragility curves generated for in-plane behavior were verified by the observed damage during the 1995 Dinar (Turkey) earthquake and fragility curves generated for out-of-plane behavior were verified by the observed damage during the 2010 Elaz?? (Turkey) earthquake. The verification results reveal that the proposed fragility-based procedure can provide an alternative for the seismic safety evaluation of unreinforced masonry buildings in Turkey. Using this procedure, it becomes possible to investigate a large population of masonry buildings located in regions of high seismic risk in a short period of time. The obtained results are valuable in the sense that they can be used as a database during the development of strategies for pre-earthquake planning and risk mitigation for earthquake prone regions of Turkey. 相似文献