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Since medieval times the Mediterranean area and in particular its coasts have witnessed a series of clashes for economic and cultural domination, partially concluded, with the Battle of Lepanto in 1571. The resulting state of uncertainty and endless terror among the population pushed military engineers to develop organized coastal defense systems consisting of a network of strongholds such as watchtowers, castles and fortresses whose structural and functional characteristics changed sensitively during the centuries. The result is a vast, heterogeneous and almost unexplored part of our built heritage. This paper focuses on the description of the coastal defensive system of the Pontifical State, concentrating on the geometrical, material and constructive characteristics of a particular structural typology: the 16th century watchtower. The aim is to establish an idealized model validated by historical information and in-situ surveys. A structural analysis is carried out, including a simple index analysis, linear dynamic and nonlinear static analyses. These analyses provide preliminary insights on the global mechanisms of failure and on the real behavior of the structure. Conclusions are drawn concerning the necessity of interventions in the perspective of an appropriate reuse of the towers which could endorse the restoration and maintenance bringing them to a new life. ...

Heritage masonry structures are often modelled as dry-jointed structures. On the one hand, it may correspond to the reality where the initial mortar was weak, missing, or has disappeared through time because of erosion and lixiviation. On the other hand, this modelling approach reduces complexity to the studied problem, both from an experimental and theoretical/numerical point of views, while being conservative. Still, for modelling purposes, in addition to the joint friction, numerical approaches require a specific elastic parameter, the dry-joint stiffness, which is often hard to estimate experimentally. This work numerically investigates the effect of the joint stiffness on the collapse of scaled-down tilting test experiments carried out on perforated dry-joint masonry shear walls. It is found that geometrical imperfections of bricks and the absence of vertical precompression load can lead to very low equivalent dry-joint stiffness, which strongly affects the results, both in terms of collapse and damage limit state (DLS) loads, with practical implications for the engineering practice. ; This work was partly financed by FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020. This study has also been funded by the STAND4HERITAGE project (New Standards for Seismic Assessment of Built Cultural Heritage) that has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant No. 833123) as an Advanced ...

Dry stone retaining walls are made of rubble stones assembled without mortar. They have shaped many regions worldwide and nowadays constitute a high cultural value, aside from their original operational role (agricultural terraces or transportation networks). However, given their high number and old age, they currently need maintenance, whereas only a few tools are available to assess their stability. In particular, the literature lacks a design tool that accounts for seismic loads. In this paper, a pseudo-static approach based on Coulomb's wedge theory is described in detail. General effects of cohesion, water pore pressure and geometrical features of the backfill are considered. On the other hand, the specificities of dry stone retaining walls are introduced through new parameters, whose values are extracted from laboratory and in-situ experiments. ; The authors want to acknowledge the French Ministry of Education and Research for their financial support through a PhD grant attributed to the first author. This work was also partly financed by FCT / MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB / 04029/2020. Finally, it has been partly funded by the STAND4HERITAGE project (new standards for seismic assessment of built cultural heritage) that has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement No. 833123), as an Advanced ...

On the 12th of June 2017 an earthquake of Mw = 6.3 struck SSE of Lesvos Island, causing one human fatality and severe damage to the built environment. The traditional settlement of Vrissa was the most affected area, having masonry structures as the majority of its building stock. The objective of the present study is two-fold: to present the structural damage and failure patterns induced by the Lesvos earthquake to masonry structures; to highlight the causes and weaknesses that led to damage, or the factors that prevented it. Particular attention is paid to traditional construction techniques and architectural features that contributed to the seismic response of the structures, either having beneficial or detrimental effect. To this end, a field reconnaissance has been conducted and meaningful technical conclusions are drawn by the observations. Structural systems of both unreinforced and timber-reinforced masonry are inspected. Besides the identification of frequent cases of local, out-of-plane and in-plane mechanisms, combined global mechanisms are also pointed out. Finally, insight into the performance of past interventions is also given, assisting the challenging task of engineering practice. ; This work was partly funded by project STAND4HERITAGE that has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement No. 833123), as an Advanced ...

Near Surface Mounted (NSM) reinforcement is an interesting technique for seismic strengthening of masonry and historical structures. Despite having several advantages compared to conventional techniques, little attention has been given to understanding the involved mechanisms (such as bond behavior) in the performance of masonry components strengthened with this reinforcement technique. This study presents an experimental and analytical investigation on the bond performance of NSM-strengthened masonry bricks aiming at filling the existing gaps in the available experimental results in the literature. The main focus is on the effect of test setup and bond length, but attention has also been given to the groove size and loading regime effect on the bond performance. The accuracy of the existing bond strength prediction models is also assessed and the required modifications are proposed. ; The second author acknowledges the financial support of the financial support of the European Union's Marie Curie Individual Fellowship program under REA grant agreement No. 701531. ...

The usage of general mortar for embedding and partially filling of units in 12 masonry prisms is evaluated through compressive tests. Filled and unfilled prisms were 13 tested in order to verify the differences on their compressive behavior. Four mortar 14 mixes with three water/cement ratios for each mix were used in tests. Results indicated 15 small differences between filled and unfilled masonry prisms. Mortar had a small 16 influence in the compressive strength of the masonry. However, a more significant 17 influence could be observed on secant elastic modulus, compressive fracture energy and 18 deformations of masonry prisms. Besides, an analytical model to represent the stress vs. 19 strain diagram of masonry prisms is proposed. The analytical model depends on the 20 compressive strength of mortar and masonry prism. Furthermore, results indicated that 21 the usage of general mortar for embedding and filling masonry prisms can be a solution 22 in terms of building technology. ; This work was partly supported by the European Commission's DISWALL contract (Development of innovative systems for reinforced masonry walls - COOP-CT-2005-018120). The first author was supported by the Alssan Programme, the European Union Programme of High Level Scholarships for Latin America, Number ...

Masonry spandrels together with shear walls are structural components of a masonry building subjected to lateral loads. Shear walls are the main components of this structural system, even if masonry spandrels are the elements that ensure the connection of shear wall panels and the distribution of stresses through the masonry piers. The use of prefabricated truss type bars in the transversal and longitudinal directions is usually considered a challenge, even if the simplicity of the applications suggested here alleviate some of the possible difficulties. This paper focus on the experimental behavior of masonry spandrels reinforced with prefabricated trusses, considering different possibilities for the arrangement of reinforcement and blocks. Reinforced spandrels with three and two hollow cell concrete blocks and with different reinforcement ratios have been built and tested using a four and three point loading test configuration. Horizontal bed joint reinforcement increased the capacity of deformation as well as the ultimate load, leading to ductile responses. Vertical reinforcement increased the shear strength of the masonry spandrels and its distribution play a central role on the shear behavior. ; This work was partly supported by contract DISWALL - "Development of innovative systems for reinforced masonry walls" - COOP-CT-2005-018120 from the European Commission. The first author was supported by the Programme Al(ss)an, the European Union Programme of High Level Scholarships for Latin America, Scholarship No. ...

A parametrical study of masonry beams through numerical modelling has been performed in order to better understand the mechanical behaviour of these elements. Boundary conditions, geometry and reinforcement ratios are the main parameters analysed in this study. The numerical simulation is performed with DIANA® software, based on the Finite Elements Method. A comparison between numerical and experimental results is presented in order to validate the simulation. In conclusion, it was verified that the behaviour of masonry beams is greatly affected by the boundary conditions and geometry, as expected. With regard to reinforcement, it was noted that horizontal reinforcement increases the flexural strength of beams. On the other hand, variation in horizontal reinforcement had no influence on the shear resistance of masonry beams. Finally, the combination of horizontal and vertical reinforcement is shown to enhance the flexural and shear behaviour of masonry beams. ; This work was in part supported by a contract from DISWall - "Development of innovative systems for reinforced masonry walls' - (COOP-CT-2005-018120) awarded by the European Commission. The first author was supported by the Programme Alssan, the European Union Programme of High Level Scholarships for Latin America, Scholarship no ...

This paper deals with the numerical assessment of the influence of parameters such as pre-compression level, aspect ratio, vertical and horizontal reinforcement ratios and boundary conditions on the lateral strength of masonry walls under in-plane loading. The numerical study is performed through the software DIANA® based on the Finite Element Method. The validation of the numerical model is carried out from a database of available experimental results on masonry walls tested under cyclic lateral loading. Numerical results revealed that boundary conditions play a central role on the lateral behavior of masonry walls under in-plane loading and determine the influence of level of pre-compression as well as the reinforcement ratio on the wall strength. The lateral capacity of walls decreases with the increase of aspect ratio and with the decrease of pre-compression. Vertical steel bars appear to have almost no influence in the shear strength of masonry walls and horizontal reinforcement only increases the lateral strength of masonry walls if the shear response of the walls is determinant for failure, which is directly related to the boundary conditions. ; This work was partly supported by contract DISWALL - "Development of innovative systems for reinforced masonry walls" - COOP-CT-2005-018120 from the European Commission. The first author was supported by the Programme Alssan, the European Union Programme of High Level Scholarships for Latin America, Scholarship No. ...

Mortar is the material responsible for distribution of stresses in masonry structures. Knowledge about the fresh and hardened properties of mortar is fundamental to ensure a good performance of masonry walls. Water/cement ratio and aggregates grading are among several variables that influence physical and mechanical behaviour of mortars. An experimental program is presented in order to evaluate the influence of aggregates grading and water/cement ratio in workability and hardened properties of mortars. Eighteen compositions of mortar are prepared using three relations cement:lime:sand, two types of sand and three water/cement ratios. Specimens are analyzed through flow table test, compressive and flexural strength tests. Results indicate that the increase of water/cement ratio reduces the values of hardened properties and increases the workability. Besides, sands grading has no influence in compressive strength. On the other hand, significant differences in deformation capacity of mortars were verified with the variation of the type of sand. Finally, some correlations are presented among hardened properties and the compressive strength. ; This work was partly supported by contract DISWALL - "Development of innovative systems for reinforced masonry walls" - COOP-CT-2005-018120 from the European Commission. The first author was supported by the Programme Al beta an, the European Union Programme of High Level Scholarships for Latin America, Scholarship No. ...

An innovative system for reinforced concrete masonry walls based on the combination of vertical and horizontal trussed reinforcement is proposed. The mechanical characterization of the seismic behavior of such reinforced masonry walls is based on static cyclic tests carried out on panels with appropriate geometry. The influence of the factors influencing the in-plane cyclic behavior of concrete masonry walls, such as the horizontal reinforcement, precompression, and masonry bond pattern, is discussed. The results are analyzed in terms of failure modes and force versus displacement diagrams, from which the seismic performance is assessed based on the ductility and energy capacity dissipation. The results stressed that the increase on the precompression level leads to a stiffer and more brittle lateral behavior of the masonry walls. The presence of horizontal reinforcement ensures better control and better distribution of cracking, even if only a marginal increase of lateral strength was found in the particular testing program. ; This work was partly supported by contract DISWALL – "Development of innovative systems for reinforced masonry walls" – COOP-CT-2005-018120 from the European Commission. The first author was supported by the Programme Alβan, the European Union Programme of High Level Scholarships for Latin America, Scholarship nº ...

This paper focus on the experimental flexural behavior of masonry beams. In the sequence of the development of a novel structural solution for reinforced masonry walls at University of Minho, different possibilities for the construction of lintels with concrete block masonry have been tested. Reinforced concrete beams with three and two hollow cell concrete blocks and with different reinforcement ratios have been built and tested in a four point loading test configuration. It was clear that horizontal bed joint reinforcement increased the ultimate flexure capacity as well as the ultimate deflection, leading to much more ductile responses. Moreover, it was also clear that a more deep analysis should be made regarding the role of the compressive strength of masonry in the parallel direction to the bed joints on the global behavior of the masonry beams. ; This work was partly supported by contract DISWALL – "Development of innovative systems for reinforced masonry walls" – COOP-CT-2005-018120 from the European Commission. The first author was supported by the Programme AlBan, the European Union Programme of High Level Scholarships for Latin America, Scholarship nº ...

Attention is given to the mechanical properties of concrete block masonry, with respect to its compressive and tensile strength. These properties are important parameters in the in-plane lateral behaviour of masonry walls, determining their resistance and ductility. Such properties play also a central role when analytical and numerical analysis is used for simulating or predicting the behaviour of masonry structures. The influence of two selected parameters on the mechanical properties of masonry is discussed, namely the geometry of the units and the filling of the vertical joints. Results show that masonry under compression behaves as a homogeneous material and the stress-strain diagrams can be represented by a parabola similarly to what is suggested for structural concrete. in case of tensile strength, filling of vertical joints appears to influence considerably the tensile strength. The filling of the vertical joints increased the strength but lead to a more brittle behaviour. ; The first author was supported by the Programme Alβan, the European Union Programme of High Level Scholarships for Latin America, Scholarship nº ...

This paper presents a user-friendly, CAD-interfaced methodology for the rapid seismic assessment of historic masonry structures. The proposed multi-level procedure consists of a two-step analysis that combines upper bound limit analysis with non-linear dynamic (rocking) analysis to solve for seismic collapse in a computationally-efficient manner. In the first step, the failure mechanisms are defined by means of parameterization of the failure surfaces. Hence, the upper bound limit theorem of the limit analysis, coupled with a heuristic solver, is subsequently adopted to search for the load multiplier's minimum value and the macro-block geometry. In the second step, the kinematic constants defining the rocking equation of motion are automatically computed for the refined macro-block model, which can be solved for representative time-histories. The proposed methodology has been entirely integrated in the user-friendly visual programming environment offered by Rhinoceros3D + Grasshopper, allowing it to be used by students, researchers and practicing structural engineers. Unlike time-consuming advanced methods of analysis, the proposed method allows users to perform a seismic assessment of masonry buildings in a rapid and computationally-efficient manner. Such an approach is particularly useful for territorial scale vulnerability analysis (e.g., for risk assessment and mitigation historic city centres) or as post-seismic event response (when the safety and stability of a large number of buildings need to be assessed with limited resources). The capabilities of the tool are demonstrated by comparing its predictions with those arising from the literature as well as from code-based assessment methods for three case studies. ; This work was partly funded by project STAND4HERITAGE that has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement No. 833123), as an Advanced ...

The number of tall housing buildings using cross laminated timber (CLT) as the main structural material has been growing all around the world but especially in Europe. This kind of construction has already proven to be a solution with a sustainable profile and despite the conflicts with some building codes and some countries legislation, this construction material is able to shape safe structures. However, to get the full confidence of the public, several researches focused on main CLT restrictions are still under development, such as fire safety, strength of connections, structural behavior, acoustics and durability. This last point is of huge importance considering timber's propensity for rotting and its known hygroscopic behavior. If humidity effects are not considered during the building design as well as the structure's integrity the people's wellbeing can be compromised. The content of the present paper aims to outline important recommendations concerning the reduction of humidity causing damages in tall timber buildings. For that, CLT/glulam hybrid construction system (Urban Timber system) is used to illustrate and describe suggested construction details of a timber building, from the foundations to the roof: the most cautious solution for foundations is to resort to reinforced concrete, in case of biological attacks or unexpected hazards; facades have to ensure the protection of timber structural elements from contact with moisture either through insulation materials or by glazed walls; windows in contact with timber ends should be able to prevent water to reach them; connection between timber elements must predict swelling/shrinkage movements of timber; at least an efficient rain water drainage has to be guaranteed by the balconies and the roof ...