Reinforcement of the 18th Century Buttresses of Maniace Castle: Design and Execution

ABSTRACT

Maniace Castle, built on Ortygia island in Siracusa (Italy) in the first half of the 13th century and hosting a magnificent hypostyle hall (the Salone), a square area covered by 25 cross vaults supported by columns, was severely damaged by the 1693 earthquake and the explosion of the ammunition dump in 1704. The buttresses, built immediately afterward to counteract the thrust of the 10 surviving vaults, did not guarantee adequate seismic safety so that a metal scaffolding was installed in 2001 to prevent an overturning mechanism. This article discusses the design and execution of an external pre-stressing steel system to increase existing buttress strength and the seismic capacity of the Salone, starting with historical and constructional analyses and dealing with both analytical and technical aspects. The monitoring system installed to detect structural response during and after the working execution is shown, along with some of the data acquired so far.     

Minimum Thrust of Rounded Cross Vaults

This study analyzes the static behavior of the rounded cross vaults based on the limit analysis approach developed for masonry structures and adopts a rigid no-tension constitutive model with no sliding. The kinematic theorem of the limit analysis with a compatible tridimensional mechanism is applied on these structures with the aim of evaluating the minimum thrust. In this way it was possible to build some abaci in which the ratio between the minimum thrust and the weight is plotted versus the geometrical characteristics of the vaults. Finally, the proposed abaci are used to calculate the thrust of the main vault of the Diocletian Baths in Rome.     

Geometry,Construction and Structural Analysis of the Crossed-Arch Vault of the Chapel of Villaviciosa,in the Mosque of Córdoba

The vault of Villaviciosa is one of the oldest existing examples of a true ribbed vault, and is the first of the crossed-arch type. Although its perfection suggests earlier trials, none has been found so far. It predates the oldest Romanesque ribbed vaults by more than a century. Notwithstanding its importance, no construction and structural study has ever been done; neither has an accurate survey been published. The purpose of this article is to fill this gap in the history of vault construction. A detailed survey has been made, providing the first accurate drawings of the vault. A close inspection of the extrados, completed with a visual inspection of interior damages, has allowed ascertaining the main construction features. With the geometry and the material data a structural analysis has been carried out. This analysis explains the fundamental structural behavior of the vault and throws new light into some historical issues; for example, it leads to discarding the widespread belief that the ribs are decorative: they are supporting the weight of the vault.     

Experimental Studies on Buried Barrel Vaults

The paper concerns an interaction problem between soil and masonry vaults in historic buildings. A particular emphasis was placed on the influence of finishing method of vaults extrados and fill material properties on the behavior of masonry vaults. The results of experimental studies on barrel vaults with and without backfill are presented. During the experiments three finishing methods of vaults extrados and three fill materials were investigated. The results of the experiments show that the presence of backfill and type of vaults extrados finish affect the behavior and load-carrying capacity of tested elements. Moreover, tests were performed on vaults without fill for comparative purposes. The comparison of experimental results obtained for specimens with and without fill shows that the presence of backfill in vault haunches modifies the failure mechanism and increases load capacity of the analysed models. The presented results confirm the importance of backfill as a structural element of vaulted structures.     

A Hybrid Masonry and Steel Mirror-Type Vault with Lunettes: Survey and Structural Analysis

ABSTRACT

The structural analysis of a mirror-type vault, consisting of a single- or double-curvature perimeter and a nearly flat part, is carried out. The vault is similar to a number of hybrid iron (or steel) and masonry vaults built between the late 19th century and the early 20th century to span large halls. The numerical analyses were preceded by an accurate geometrical survey and mechanical tests aimed at evaluating the properties of the materials. Thermography allowed the complex brick pattern of the vault to be detected. The influence of rib-walls (frenelli) and the material anisotropy on the stress and deformation of the vault is discussed. Eventually, attention is focused on one of the segmental vaults in the central part of the structure: it is found that the stress can be safely estimated by assuming its boundary to be fixed.     

VAULTED CONSTRUCTION IN FRENCH MEGALITHIC TOMBS

Summary. The passage graves of France now have a serious claim to be the earliest known corbelled vaults. The structural mechanics of these buildings is investigated through an analysis of the vaults at Barnenez and Ile Carn, the only examples surviving complete. The cultural setting of the French passage graves and their typology are briefly reviewed. Chambers G, G'and F of the great mound at Barnenez and the central chamber of Ile Carn are described with reference to the materials used and their construction. The theory underlying our analysis of corbelling is introduced and the results of the analysis summarised. All three of the chambers at Barnenez are found to follow the same formula, indicating the same technique was used over the different phases of construction. Ile Carn, however, is vaulted in a completely different manner. These findings are placed in the broader context of the development of megalithic architecture.     

Historic Barrel Vaults Undergoing Differential Settlements

ABSTRACT

A principal reason of damage in historic masonry vaults consists in relative displacements of the vaults’ abutments. Excluding the case of seismic-induced damage, cracks are often produced by differential settlements generated by the lateral wall instability or soil degradation (e.g., due to stress concentrations, non-uniform soil stratigraphy, flooding phenomena etc.). When dealing with historic vaults, the effects of long-term deformation processes cannot often be linked directly to causes, which may also be unknown. In this article, the effects of differential settlements on historic masonry barrel vaults are investigated. An efficient 3D contact-based model was developed to reproduce experiments on a scaled pointed barrel vault (representative of a typology of late-medieval barrel vaults in Scotland) under non-uniform differential settlement. First, the numerical model is used to simulate the experimental campaign, achieving good agreement in terms of crack pattern (longitudinal shear) and transverse-longitudinal deformation profiles. Then, further analyses are carried out to gain insight on the effects of several plausible uniform and non-uniform settlement patterns on representative historic barrel vaults. Various settlement configurations were analysed and complex failure patterns observed. This study could help analysts in understanding the nature of on-going deformation process in historic masonry vaults and engineers in the design of strengthening strategies.     

The Dynamic Behavior of the Basilica of San Francesco in Assisi Using Simplified Analytical Models

The Basilica of San Francesco in Assisi endured stronger earthquakes for centuries before 1997 earthquake, which generated the collapse of the two vaults. Experts blame as possible reasons of collapse the damage cumulated from previous earthquakes and/or the retrofitting made to the structure over its lifetime. This article presents the history of the retrofit interventions of the Basilica through the centuries, focusing mainly on the roof, which has been subjected to three major restorations through its life. It is shown using simple analytical models that the cumulative effects of the changes made to the roof of the Basilica affected the structure’s dynamic behavior in a negative manner, increasing the seismic loads on the existing structural members. In particular, the numerical results show that the 1958 roof intervention has stiffened the structure, redistributing the seismic loads on the façade and the transept. This overload might explain the collapse of the two Gothic vaults during 1997 earthquake.     

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.     

旅游业回扣／佣金问题的理论思考——新制度主义分析范式

本文在继承已有研究成果基础上,力图拓展完善旅游业回扣／佣金潜规则的研究思路和方法,即以新制度经济学为切入点,结合历史发展过程的纵向分析和动态平衡的横向分析,对旅游业这一潜规则进行深入的阐述与探讨。本文采用产权理论、交易费用理论和路径依赖理论对回扣／佣金潜规则现象进行了阐释,认为产权与交易费用的界定是这一规则产生与发展的核心动力,而制度均衡、囚徒困境及正式制度的监管失效是这一潜规则得以维持现状的三大原因。在此分析基础上,从新制度经济学的视角提出相应的引导之道,包括产权的安排分配、引入正向的信念体系及内外部监管变量的介入三大制度创新安排。     

PROVENANCING OF LIGHTWEIGHT VOLCANIC STONES USED IN ANCIENT ROMAN CONCRETE VAULTING: EVIDENCE FROM TURKEY AND TUNISIA

The mastery of the use of lightweight rocks in concrete as a means of controlling the thrusts of large‐scale vaults was among the most important contributions of the Roman builders to the development of vaulted architecture. The string of volcanoes along the Tyrrhenian coast of Italy produced a variety of lightweight rocks, which allowed the builders in Rome to develop highly sophisticated ways of manipulating form and mass to create stable structures. The use of lighter rocks in vaults and heavier in foundations occurs from the mid‐first century bc in Rome, but the systematic use of imported lightweight rocks only began in the early second century ad under Trajan ( Lancaster 2005 , 59–64). Soon thereafter, the technique of using lightweight stones to build large vaults spread throughout the empire, usually to areas that had a local source of lightweight volcanic material. However, there was also a seaborne trade in lightweight rocks to areas that did not have local sources of such material. The intention of our analysis is to determine as precisely as possible the provenance of the lightweight stones used in vaulting of two areas of the Mediterranean, modern Turkey (ancient Cilicia) and Tunisia (ancient Africa Proconsularis), and thus to provide a better understanding of the nature of this trade.     

论史料

史料是一种语言,对史料性质的分析本质上是一种“元分析”。只有在史料系统内部,史料才具有客观性。史料的客观性是一种语言的客观性。历史研究的客观性就是运用史料的规范性,即语言游戏的规则性。史料与历史的关系是一种假关系。史料不能直接产生理论,但可以充分限制理论;史料虽不能肯定什么理论是好的,但可以肯定什么理论是不好的。     

The Groin Vaults of St. John Hospital in Jerusalem: An Experimental Analysis on a Scale Model

The St. John Hospital is part of a larger complex of buildings known as the Hospitallers Quarter, located south of the Holy Sepulchre in Jerusalem. At present, the hospital looks like an irregular volume both in height and in plan; it is covered by ten groin vaults resting on very stocky pillars. Each vault is formed by intersecting double curvature surfaces. In order to verify the effectiveness of continuous carbon fiber reinforced polymer sheets reinforcement, bonded at the extrados of vaults, laboratory tests were carried out on a 1:5 scale model, built with materials and construction techniques similar to those of the real building. Experimental tests were performed on the unstrengthened and strengthened vault. The experimental results shown that the strengthening system is able to increase the collapse load of the vault, without substantial variation of the initial stiffness.     

A Study on the Evolution in Design and Calculation of Iron and Steel Structures over the Mid 19th Century in Western and Central Europe

ABSTRACT

The design of metallic structures in the 19th century is a subject topic of much admiration, as many emblematic structures that are currently withstanding the test of time have become part of our built cultural heritage. Knowledge on the assumptions and design procedures available at that time is of importance to structural engineering nowadays. It allows for the understanding, maintaining and safe extending of the service life of historical metallic structures. The goal of this article is to describe the evolution in the design and calculation of metallic structures during the second half of the 19th century, with focus on Western and Central Europe. Special attention is paid to the similarities and differences between the 19th century design rules and the current structural design standards. Based on a literature survey, the evolution in terms of load definition, calculation methods, material properties, and verifications are described. Different design aspects are illustrated through a case study: The Garabit viaduct in France.     

THE ENDURING PUBLIC STRUGGLE TO CONSTRUCT,CONTROL, AND CHALLENGE HISTORICAL MEMORIES

Sumit Guha's History and Collective Memory in South Asia, 1200–2000 develops important arguments about the public significance of historical knowledge and the essential role of historians in public life. All societies need collective memories to sustain their cultural identities, as Guha shows in this wide‐ranging account of how such memories have been constructed in South Asian societies since the thirteenth century. The knowledge of historical experts is increasingly challenged or derided by contemporary social groups and political activists, who circulate their own historical narratives via new networks of communication. Political uses of historical knowledge are not new, however, as Guha shows in detailed accounts of how Hindu, Muslim, and British imperial regimes all used historical narratives to justify their own power. He also explains how other social groups challenged official historical narratives with their own popular stories about the past. This book contributes to recent work in global intellectual history by comparing similarities in the historical practices of premodern Europe and South Asia, discussing the cross‐cultural exchanges in colonial‐era institutions, and describing postcolonial challenges to European ideas. Guha thus offers an insightful analysis of how social and political forces influence and respond to the cloistered institutions that produce historical knowledge and construct collective memories. He concludes that evidence‐based historical narratives must be continually defended amid current public assaults on historical knowledge in both South Asia and the United States. More generally, Guha's book suggests the need for ongoing analysis of how public events, social conflicts, and new communication systems can reshape or discredit the work of historical experts.     

Coupling Hydrotoponymy and GIS Cartography: A Case Study of Hydrohistorical Issues in Urban Groundwater Systems,Porto, NW Portugal

The aim of this multidisciplinary study is to retrospectively examine hydrohistorical issues, namely hydrogeographic, hydrotoponymical and hydrogeological features, in order to assess the evolution of the Porto urban groundwater system (NW Portugal). To achieve these goals, the comparison of two main field inventories in a large urban region was performed by (i) historical mapping of sources and groundwater data from scientific reports spanning the late 17th century to the early 20th; and (ii) hydrogeologic and hydrotoponymical field inventory performed under current conditions. These field inventories permitted the location of springs, dug wells, fountains, public washing places and underground water galleries, which collected groundwater to supply the population of Porto until the early 20th century. This study also allowed the development of a hydrotoponymical classification for urban areas and a field hydrotoponymical inventory data sheet. This research integrated several techniques based on historical hydrogeography, hydrogeology and urban geosciences. The results of the field inventories were combined into both a database and a Geographical Information System (GIS) platform. This unified methodology allowed a cross‐check and analysis of several levels of information, namely hydrotoponymy, hydroclimatology, hydrogeology, structural geology and geomorphology. This perspective led to an assessment of the evolution of the quality of water resources in large urban areas over time. In addition, the role of hydrotoponymical features is presented in order to support the hydrogeological conceptual model for large urbanised areas.     

HISTORY'S DEMARCATION PROBLEM

In his 1998 book Heterocosmica: Fiction and Possible Worlds, Lubomír Dole?el put forth a theory of narrative fiction based on the interdisciplinary framework of possible worlds. In Possible Worlds of Fiction and History: The Postmodern Stage, Dole?el takes his earlier theory further and applies it to historiography as well, with the specific aim of showing how the study of history might be defended against the postmodern challenge via the use of possible worlds (PW) semantics. Dole?el's book is essentially an argument against the postmodern views expressed by Roland Barthes and Hayden White, who have claimed that fundamentally, there is no difference between fictional and historical narratives. According to Dole?el, this difference can be saved if the focus of attention is shifted from the textual features of these narratives to the fictional or historical worlds that the narratives project. Dole?el's comparison of fictional and historical worlds to each other is quite illuminating and thorough. However, the question remains whether the application of PW semantics does anything besides offering a detailed analysis of the structure of the different types of narrative worlds. After all, one should not overlook the perhaps more practical way of differentiating between historical and fictional narratives through their institutional status. Furthermore, we argue that by focusing on the properties of the end products, that is, the resulting narratives, Dole?el concedes too much to postmodernists. A stronger way to give postmodernists a taste of their own medicine would be to argue that the rules that historians follow in the process of generating, constructing, and evaluating weighed causal explanations (or historical models of the past) are fundamentally different from whatever rules govern the generation and construction of fiction.     

Southchurch Hall

Abstract

In 1437 Sherborne Abbey church was deliberately set on fire as the result of a quarrel between certain parishioners and the monks. The tower and chancel of the church were being rebuilt at the time. This paper records the results of a detailed study of the masonry which had been discoloured by scorching, and the conclusions deduced therefrom. These include: some modifications of the story of the fire as interpreted by Professor R. Willis in 1865, and deductions on the course and extent of the fire, the stage that the rebuilding had reached and its sequence of construction. The survey also proves that the fan vaults and clerestory windows of the east end were completed after the fire to their original design. The paper ends with some discussion about the possible architect, and an assessment of the design and influence of the fan vaults.     

The Catastrophic Repairs of Holyrood Abbey Church in 1760

The collapse of the significant church of Holyrood Abbey in Edinburgh in December 1768 is discussed as the result of the ill-conceived repair of the roof in 1760, i.e., the substitution of the timber trusses with closelyspaced diaphragm masonry walls that aggravated the delicate equilibrium of the vaults and the poor state of a building being mutilated over 250 years. This study interprets these repairs by demonstrating the authorship and partnership of the architect John Douglas with the mason-developer James McPherson, who combined architectural ambition (the aesthetics of a flagstone roof) with the (cheaper) option of diaphragms, which would not involve a wright. The detailed examination of the procurement, the process of the intervention, the collapse, and the limited impact of its aftermath, are framed in a wider technical and historical context in Edinburgh and Scotland, during a period marked by several failures of medieval churches, and reveals a poor understanding of a critical element in Gothic construction. Analysis of all public archive material available sheds light on key events of the case, and critical study of the work of the two partners’ attempts to identify the intentions of their project, whose limitations were inevitable once the partnership was formed.