Determination of Shear Strength of Masonry Panels Through Different Tests

This study addresses the problem of evaluation of strength of masonry walls. In-plane behavior of masonry panels has been studied under monotonic diagonal-compression and shear-compression loading in quasi-static test facility. The results of 35 laboratory and in situ tests are analyzed to show that in the case of the diagonal compression test results are lower than the strength of masonry walls evaluated trough the shear-compression test, highlighting the problem of choosing the test which best simulates to the real behavior of the masonry when stressed by lateral loads. A presentation is also given of the results of a F.E. investigation for shear strength evaluation of masonry walls. F.E. modeling non-linear procedure was used for the representation of masonry panels. The numerical simulations are compared with experimental results and the reliability of the different finite element models is discussed, thus confirming the different shear strength values measured in the experimental campaign.     

Discrete Element Modeling of Groin Vault Displacement Capacity

Displacements experienced by many historic masonry structures concentrate at masonry joints and can be large before collapse is a concern, making modeling of stability using discrete element modeling (DEM) particularly suitable. In this study, masonry groin vault and arch models with several geometries were subjected to horizontal and vertical support displacements using DEM. Support movements were applied in a quasi-static manner to simulate the support settlement process. Displacements at collapse and at the point when the first block fell from the vault were recorded. Block separation and mechanisms were also noted during the simulations. A two-dimensional (2D) analytical model using thrust line analysis was developed to help evaluate the DEM results. In general, the displacements at first block fall were relatively large but significantly less than those at collapse. The groin vaults and arches exhibited significantly higher capacity to sustain vertical support displacement compared to horizontal displacements. For many geometries, the DEM collapse displacements of the groin vaults compared reasonably well to similar arches, indicating that the displacement capacity of groin vaults can be reasonably estimated using 2D simplifications. However, for certain geometries, three-dimensional effects were found to significantly affect displacement capacity.     

Effectiveness of FRCM Reinforcement Applied to Masonry Walls Subject to Axial Force and Out-Of-Plane Loads Evaluated by Experimental and Numerical Studies

ABSTRACT

An experimental campaign and a numerical analysis devoted to the investigation of the out-of-plane behavior of masonry walls reinforced with Fiber Reinforced Cementitious Matrix (FRCM) are presented here. The main goal of this study is to analyze and evaluate the effectiveness of the strengthening system, by discussing failure modes and capacity of strengthened masonry walls, in order to assess their behavior under out-of-plane horizontal actions, such as, for example, seismic actions. A purposely designed experimental set-up, able to separately and independently apply an axial force and out-of-plane horizontal actions on masonry walls, was used. Experimental results are discussed and compared with the outcomes of nonlinear analyses performed on simplified finite element models of the walls. A proper evaluation of the flexural capacity of FRCM strengthened walls is the first step of the ongoing process of drawing reliable code guidelines leading to a safe design of strengthened masonry structures.     

Seismic Assessment of a Historical Masonry Building in Switzerland: The “Ancien Hôpital De Sion”

This article presents the results of the evaluation of the seismic safety of the Ancien Hôpital de Sion, an important Swiss architectural heritage building, situated in the Canton of Valais, the region with the highest seismic hazard in Switzerland. Three-dimensional Applied Element (AEM) modeling of the whole structure has been performed and validated. The adopted modeling strategy, together with nonlinear dynamic analysis, was able to represent the actual behavior and failure mechanisms typical of complex masonry structures, in addition to a good computational efficiency compared to other available numerical approaches. The local collapse mechanisms have been also studied through a kinematic limit analysis based on rigid block rotation. Both linear and nonlinear approaches have been followed together with the capacity spectrum method. The results provided by the different methodologies have been compared with the aim to provide possible insights concerning a general procedure for the assessment of the safety of such type of structures.     

Review of Out-of-Plane Seismic Assessment Techniques Applied To Existing Masonry Buildings

ABSTRACT

Observations after strong earthquakes show that out-of-plane failure of unreinforced masonry elements probably constitutes the most serious life-safety hazard for this type of construction. Existing unreinforced masonry buildings tend to be more vulnerable than new buildings, not only because they have been designed to little or no seismic loading requirements, but also because connections among load-bearing walls and with horizontal structures are not always adequate. Consequently, several types of mechanisms can be activated due to separation from the rest of the construction. Even when connections are effective, out-of-plane failure can be induced by excessive vertical and/or horizontal slenderness of walls (length/thickness ratio). The awareness of such vulnerability has encouraged research in the field, which is summarized in this article. An outline of past research on force-based and displacement-based assessment is given and their translation into international codes is summarized. Strong and weak points of codified assessment procedures are presented through a comparison with parametric nonlinear dynamic analyses of three recurring out-of-plane mechanisms. The assessment strategies are marked by substantial scatter, which can be reduced through an energy-based assessment.     

Interaction Curves for In-Plane and Out-of-Plane Behaviors of Unreinforced Masonry Walls

Different types of macro-elements have been proposed to simulate the behavior of unreinforced masonry (URM) structures under seismic loads. In many of these, macro-elements URM walls are replaced with beam elements with different hysteretic behaviors. The effect of out-of-plane loading or change of gravity load due to the overturning moment is usually not considered in the behavior of these macro-elements. This article presents interaction curves for bidirectional loadings of unreinforced masonry walls to investigate the importance of these factors. Two parameters are systematically changed to derive the interaction curves for a wall with specific dimensions, including compressive traction atop the wall to represent gravity loading, and loading angle that represents a combination of in-plane and out-of-plane earthquake loadings. Interaction curves are developed considering various possible failure modes for bricks and mortar, including tension, crushing and a combination of shear and compression/tension failures. The proposed interaction curves show the initiation of failure of URM walls as a function of compressive traction and loading angle. Several examples are presented for URM walls with different aspect ratios to aid in understanding the effects of various parameters on the derived interaction curves. Finally, for a specific case, the derived interaction curve is compared with nonlinear finite element results and ASCE41. The results show that, as a simplified method, the derived interaction curves can be used for the preliminary evaluation of URM walls under bidirectional loadings.     

Community sustainability and resilience: similarities,differences and indicators

Sustainability has been a core conceptual framework for community development since the approach was popularized in 1987, although in its essence it reflects a long history of environmental conservation reactions to industrialization. Resilience, as a framework for understanding and approaching community development, emerged more gradually out of ecological studies in the 1980s, but has only recently, since the mid-2000s, emerged as a focus of public interest as a way of responding and adapting to the planet's growing anthropogenic changes. For many, sustainability and resilience are slightly nuanced perspectives on the same phenomenon. For others, however, there are distinct differences between them, with sustainability's conservation goals being in opposition to the adaptation goals of resilience. Two major reasons for these confusions are (1) both concepts are defined and used in many different ways to achieve a variety of political goals that may not reflect their core definitions, and (2) both concepts share similar goals and some common approaches, such as a focus on climate change and seeking a balance between humans and nature. Returning to the core definitions of conservation and adaptation helps to clarify their similarities and differences, as well as to articulate indicators for understanding how each applies to community tourism development. Indicators from research in rural Taiwan tourism communities were therefore based on responses to the questions: What does the community want to conserve and how do they want to do it (sustainability)? What do they want to change and how do they want to do it (resilience)? Preliminary results suggest that the new ideal community is the one that is both sustainable and resilient.     

馆藏文物保护中数字建模技术应用研究

随着三维扫描技术的发展,三维扫描技术的应用范围逐步扩大。在文物保护领域,三维扫描技术也有着重要的应用。同时,作为博物馆数字化的一个重要组成部分,馆藏文物保护与修复的数字化技术也在不断深入。因此,首都博物馆文物保护分析实验室应用三维激光扫描技术开展了一系列在文物保护分析过程中的数字建模工作,特别是对文物修复和复制的辅助作用进行了有益的尝试。针对工作过程中遇到的技术难点诸如偏色、背景干扰等进行了分析,并提出解决办法,旨在供文物保护领域和计算机技术领域共同探讨研究。     

Quantitative basin modeling: present state and future developments towards predictability

A critique review of the state of quantitative basin modeling is presented. Over the last 15 years, a number of models are proposed to advance our understanding of basin evolution. However, as of present, most basin models are two dimensional (2‐D) and subject to significant simplifications such as depth‐ or effective stress‐dependent porosity, no stress calculations, isotropic fracture permeability, etc. In this paper, promising areas for future development are identified. The use of extensive data sets to calibrate basin models requires a comprehensive reaction, transport, mechanical (RTM) model in order to generate the synthetic response. An automated approach to integrate comprehensive basin modeling and seismic, well‐log and other type of data is suggested. The approach takes advantage of comprehensive RTM basin modeling to complete an algorithm based on information theory that places basin modeling on a rigorous foundation. Incompleteness in a model can self‐consistently be compensated for by an increase in the amount of observed data used. The method can be used to calibrate the transport, mechanical, or other laws underlying the model. As the procedure is fully automated, the predictions can be continuously updated as new observed data become available. Finally, the procedure makes it possible to augment the model itself as new processes are added in a way that is dictated by the available data. In summary, the automated data/model integration places basin simulation in a novel context of informatics that allows for data to be used to minimize and assess risk in the prediction of reservoir location and characteristics.     

泰州水关遗址结构分析及修缮设计

水关是古城墙建筑的一个重要元素,对研究古城墙布局及城市演变具有重要意义。为了对泰州水关遗址进行科学保护,首先通过现场调研,对泰州水关遗址的残损进行分析,找出其可见的病害,包括墙体残损、基础残损、券体残损及木桩残损;然后通过有限元模拟分析其结构性能,找出其隐在的病害,主要是地基和墙体问题。最后,综合残损调研及数值模拟结果,提出了适用于水关遗址的修缮设计方法,包括地基加固、墙体加固以及木桩保护方法。     

Methods and Approaches for Blind Test Predictions of Out-of-Plane Behavior of Masonry Walls: A Numerical Comparative Study

ABSTRACT

Earthquakes cause severe damage to masonry structures due to inertial forces acting in the normal direction to the plane of the walls. The out-of-plane behavior of masonry walls is complex and depends on several parameters, such as material and geometric properties of walls, connections between structural elements, the characteristics of the input motions, among others. Different analytical methods and advanced numerical modeling are usually used for evaluating the out-of-plane behavior of masonry structures. Furthermore, different types of structural analysis can be adopted for this complex behavior, such as limit analysis, pushover, or nonlinear dynamic analysis.

Aiming to evaluate the capabilities of different approaches to similar problems, blind predictions were made using different approaches. For this purpose, two idealized structures were tested on a shaking table and several experts on masonry structures were invited to present blind predictions on the response of the structures, aiming at evaluating the available tools for the out-of-plane assessment of masonry structures. This article presents the results of the blind test predictions and the comparison with the experimental results, namely in terms of formed collapsed mechanisms and control outputs (PGA or maximum displacements), taking into account the selected tools to perform the analysis.     

Study of interactions between polyethylene glycol and archaeological wood components by C high-resolution solid-state CP-MAS NMR

While use of polyethylene glycols, PEG, polymers for archaeological wood conservation has been well established, there is almost no study of such composite materials with carbon thirteen high-resolution solid-sate NMR. We demonstrate that NMR is an useful analytical tool to characterize rapidly samples of conserved wooden objects. By choosing an appropriate value of the contact time (from 3 to 5 ms) for which the PEG component gives only a small residual NMR signal in the CP-MAS experiment, it is possible to edit selectively the spectra of the wood components. It allows one to visualize the degradation extent of the archaeological wood even when the conservation processes have been already applied. Moreover, by studying the kinetics of CP-MAS experiments, the time constants, T_1ρH and T_CH values for PEG moiety were computed. From these data, it is shown that either in the crude commercial product or in incorporated in archaeological woods, two components are present and they are the signatures of crystalline (or ordered) and amorphous (or disordered) molecular domains. Moreover, it was shown in the archaeological woods that almost 30% of PEG was in close molecular interactions with lignins. This study is the first evidence that the PEG in conserved wood can interact at a molecular level with wood components. It also demonstrates that the PEG diffuses inside the residual cell walls of archaeological wood. This data are important for scientists in charge of process development for the conservation of wooden artifacts.     

A COMPARATIVE STUDY OF STRENGTHENING AND RETROFITTING MEASURES FOR UNREINFORCED BRICK MASONRY MODEL UNDER CYCLIC TESTING

An experimental study on half-scale brick-masonry models with different strengthening and retrofitting measures has been studied under cyclic loading in a quasi-static test facility. The strengthening measures undertaken for the studies axe the horizontal bond beam at the lintel and sill level with a combination of vertical reinforcement at corners and openings. The retrofitting measures studied are grouting with epoxy-sand-mortar and cement-grout-injection with welded wire mesh in the cracked region. The tests reveal that the horizontal bond beam at lintel level with vertical reinforcement is effective in reducing the cracking above the lintel level. The insertion of an additional sill-band signi-ficantly reduces the cracking in walls. The epoxy-sand-mortar techniques for retrofitting of cracked regions prove to be effective enough to restore the initial strength, stiffness and deformation capacity. Although specimen retrofitted with cement-grout-injection with welded wire mesh is effective to regain the ultimate strength yet the brittle failure is observed as the specimen is stressed beyond the elastic limit.     

Authenticity and heritage conservation: seeking common complexities beyond the ‘Eastern’ and ‘Western’ dichotomy

ABSTRACT

This article challenges the claimed gulf between ‘Eastern’ and ‘Western’ concepts and approaches to heritage conservation through an analysis of the common complexities surrounding authenticity. The past few decades have witnessed an important critique of ‘Eurocentric’ notions of heritage conservation, drawing on ‘non-Western’, particularly Asian, contexts. Authenticity has been a core principle and defining element in this development. Endorsed by a series of charters and documents, a relativistic approach emphasising the cultural specificity of authenticity has been introduced alongside the European-originated materialist approach in international policy and conservation philosophy. However, the promotion of Asian difference has also contributed to an increasingly entrenched and unproductive dichotomy between ‘Eastern’ and ‘Western’ approaches to heritage. This article reveals common complexities surrounding authenticity in two countries crosscutting this dualism – China and Scotland. Drawing on a number of ethnographic projects, our analysis identifies themes that characterise the experience of authenticity across different cultural contexts. It contributes to a more nuanced understanding of the evolving relationships between heritage conservation and contemporary societies with important implications for global heritage discourses and collaborative ventures crosscutting ‘Eastern’ and ‘Western’ contexts.     

Analysis of the collapse mechanisms of medieval churches struck by the 2016 Umbrian earthquake

The 2016 Umbrian earthquake caused the collapse of several medieval churches, while it was noted that ordinary buildings only reported moderate or little damage. Researchers and technicians are looking to these religious constructions with the aim of understanding their structural behavior under seismic action. Depending on the direction of the seismic action, the typical collapse mode was the overturning of the side walls or of the church façade. This often produced the collapse of the roof structure. In many situations, the overturning was facilitated by a weak connection between the load-bearing walls. In this article, the collapse modes of three mediaeval churches are investigated. The article goes into some detail about what considerations are relevant when analyzing a historic masonry construction. The churches object of this study are located in Campi, a hamlet of Norcia, Italy. Between 2000 and 2004, a research team from the Technical University of Milan in collaboration with the Italian Ministry of Culture carried out an extensive investigation on the historic buildings of Campi, providing interesting data about the maintenance level and a summary of the structural state of the churches. These data were used in this article for a critical analysis of the causes of collapse, performed in combination with numerical simulations of the global behavior and local instability.     

A Time Series Analysis of Regional Income Inequalities and Migration in Japan, 1955–1985

This study tests the neoclassical concept of interregional migration in post–World War II Japan. The lead-lag relationship between net migration to a core area and regional income inequalities is examined by modeling an ARIMA transfer function. Until 1961, there was a rapid growth in net migration from the periphery to the core area that was accompanied by rapid divergence in regional income inequalities. Since then, migration to the core apparently has declined due to a convergence of regional income inequalities. The time series analysis indicates there has been short-run, as well as long-run, volatility in migration related to cyclical variations in economic performance in the core.     

乾陵东一翁仲裂隙调查及稳定性分析

乾陵东一翁仲病害众多,但裂隙是危及其安全的首要因素。通过现场调查确定了东一翁仲裂隙分布特征并对其稳定性进行了分析。结果表明:东一翁仲现存5条影响其稳定性的裂隙,其中3条贯通,2条局部贯通。裂隙将石刻分割为5个块体,中间块体上大下小且重心前偏,导致石刻整体前倾,为石刻失稳提供了动力来源,脚后跟块体是石刻稳定的关键块体。石刻目前处于欠稳定状态,当遇到关键块体上部破碎、钢箍断裂失效、地震荷载等任一情况时,石刻将处于失稳状态,有整体倒塌的危险。研究结果可为东一翁仲的保护工作提供科学依据。     

A GIS method for assessing the zone of human-environmental impact around archaeological sites: a test case from the Late Neolithic of Wadi Ziqlâb,Jordan

Assessing the impact of prehistoric sites on their local environment is difficult to accomplish with standard archaeological methods. Simulation modeling offers a solution to this issue, but it is first necessary to delimit a site catchment, or “zone of impact”, around archaeological sites in which to carry out human–environment interaction modeling. To that end, I have developed a new method for GIS-based catchment reconstruction and distilled it into a custom module (r.catchment) for GRASS GIS, which calculates catchments of a given area based on anisotropic travel costs from a point of origin. One method of applying this new module in exploratory catchment modeling is discussed using the pastoral economy of the Late Neolithic period in Wadi Ziqlâb, Northern Jordan as a test case. A model of Late Neolithic herding economy and ecology is constructed, which combines data from archaeology, phytogeography, range science, agronomy, and ethnohistory. Four sizes of pastoral catchments are then derived using r.catchment, and the herd ecology model is used to estimate the stocking-rate (carrying capacity) of mixed goat and sheep herds for each catchment. The human populations these herd numbers could support (between 3 and 630 people in the Wadi) are then compared with human population estimates derived from household architectural analyses (between 18 and 54 people in the Wadi) to determine the most probable catchment configurations. The results indicate that the most probable zone of impact around the known Late Neolithic sites in Wadi Ziqlâb was somewhere between 9 and 20 square kilometers, delineated by 3 and 4.5 km pasture radii respectively.     

Building Bridges across the Atlantic: the European Union Visitors Program. A Case Study for Public Diplomacy and the Transatlantic Relationship in the 1970s

This article addresses the core question of the complex interplay between Atlantic-alliance politics and European integration in the 1970s, a turning point in the European-US relationship. The analysis focuses on the European Community Visitors Program: the first European Community (EC) professional exchange programme seeking to foster mutual understanding between the Community and the United States, which is an intriguing case study in the history of transatlantic relations from a public-diplomacy standpoint. Its relevance is indeed twofold. From an intra-European perspective, it has contributed to laying the foundations for an identity discourse, upon which the narrative of a Euro-exceptionalism has been constructed from the 1970s onwards. Furthermore, as an exchange programme fostering connections among elites abroad, it has enhanced the EC's visibility outside its borders and thus promoted its recognition worldwide. At a systemic level, the ECVP - modelled after the most famous US public-diplomacy programmes - has served as a transatlantic bridge-builder and a prime tool for facilitating alliance management during the cold war, particularly in the troubled 1970s.     

OUT-OF-PLANE SEISMIC RESISTANCE OF MASONRY WALLS

Seismic vulnerability of unreinforced masonry buildings is studied by means of simplified out-of-plane collapse mechanisms that take into account connections with transversal walls. According to experimental evidence, the analysis assumes that failure is reached with a rigid body motion of a part of the facade that falls down. Two classes of mechanism are examined: the overturning of the facade due either to a vertical crack at the connection or a diagonal crack on the transversal wall, both defined resorting to a simple model of masonry fabric, viewed as a regular assembly of rigid blocks and elastic plastic joints with friction but no cohesion. The use of simplified mechanisms give rise to an explicit evaluation of the seismic resistance to changes in the geometry and in the masonry fabrics, that could be used by practising engineers. This formulation is developed for both static horizontal actions and ground velocity peak, in the belief that the latter probably gives a better approximation of seismic action, while also providing, by comparison with the results of static forces, an estimate of the behaviour factor for unreinforced masonry. Eventually, the analytical forecasts are compared with numerical results obtained by means of the distinct element method.