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.     

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.     

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.     

试论数据采集与虚拟修复在大足石刻修复中的应用

文物作为一种不可再生的宝贵资源,其本体上的保护修复工作均需慎之又慎,需遵循国际上规定的“最小干预”及“可逆性”基本原则.为此,虚拟修复成为对文物动手修复时的重要辅助手段.然而,多数文物具有复杂立体结构和色彩,传统的虚拟修复技术难以实现逼真效果.三维激光扫描是近年来飞跃发展的一项高新测绘与信息技术,具有无损、空间精度高、速度快等突出优势,在文物数字留存及相关保护应用中发挥了重要作用.三维激光扫描技术与高清摄影技术相结合,为文物的虚拟修复带来新的契机.本文结合文物虚拟修复基本需求分析,提出了基于三维激光扫描技术的文物虚拟修复关键技术与工作流程,并以国家一号石质文物保护工程——大足石刻宝顶山千手观音造像的保护修复为例,进行了应用实践,综合历史资料和现有数据的分析,实现了三维形态及色彩的虚拟修复.结果表明,基于三维扫描的虚拟修复能够提供更为逼真的三维虚拟修复模型,供修复专家研究参考.     

清末刻本书叶掉墨原因与修复方法初探

清末刻本是清朝晚期使用雕版印刷的古籍,是古籍资源保护与利用的重点对象之一。在日常翻阅、数字化扫描及修复流程中常出现掉墨现象,严重影响其文献价值,但该问题尚未受到足够关注。本研究针对古籍掉墨问题设计了几种评估方法,对二十余种清末刻本的掉墨程度进行了调查,并结合修复实际对掉墨原因进行了初步的剖析,建议对掉墨严重的刻本采用刷涂法和包裹法进行保护处理。本研究对古籍刻本的墨迹保护具有实践参考意义。     

谈《淳化阁帖》“银锭纹”问题

《淳化阁帖》历代翻刻频多,版本繁杂,许多问题千年来争讼未果。本文根据帖版"银锭"的材质和制作工序,同时结合考古发掘资料及实物,指出银锭榫技术在北宋已相当成熟,石板亦可用它加以连接;《阁帖》上的银锭纹,即来源于这种用于联结、加固的银锭榫,但这也不等于说锔银锭棒的帖板就是祖版。传世带银锭纹的《阁帖》有数种之多,而情况各不相同。     

The role of the Italian Central Institute of Restoration in the field of underwater archaeology

In 1987, given the importance and complexity of the correct recovery and conservation procedures for underwater archaeological finds, an Underwater Archaeological Operations Unit was set up within the Italian Central Institute for Restoration. This Unit is made up of archaeologists, conservators, biologists and chemists, all of whom are underwater experts. It provides consultancy services and scientific and technical assistance for problems relating to the recovery, conservation, protection, and restoration of underwater archaeological heritage at the request of the Archaeological Superintendents. Great attention is paid to the professional training of underwater conservators. Specialized courses in the conservation of materials of underwater provenance are organized as part of its programme. This paper illustrates some of the main initiatives both in the restoration of archaeological objects and in training, in which the Institute has been involved, since the Underwater Unit was created.     

Photoshop虚拟修复在奉国寺壁画保护中的应用

义县奉国寺属辽代皇家寺院,寺内主殿大雄殿为辽代建筑,殿内四壁满绘壁画,规模宏大,绘制技法独特,对研究元代壁画具有极高的价值。但因战乱、地震等灾害受损严重,壁画保存现状堪忧。由于其保护难度大,病理研究尚不明确,目前无法对其进行实体保护修复,因此通过Photoshop对壁画线条病害、颜料病害和结构病害进行虚拟修复,虚拟修复内容包括对壁画表面覆盖物进行清理,对线条和颜料层缺失部分进行补全,对变色、褪色区域进行色彩校正,修复结果表明画面复原取得了良好的效果。Photoshop虚拟修复对于壁画保护是一种可行且有效的方法,可为之后的壁画保护提供参考、借鉴,同时也可以最大程度地提取壁画信息,有利于壁画的展示。研究结果表明Photoshop虚拟修复是数字化保护文物发展的重要方向。     

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.     

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.     

Response of Alum Rock springs to the October 30, 2007 Alum Rock earthquake and implications for the origin of increased discharge after earthquakes

The origins of increased stream flow and spring discharge following earthquakes have been the subject of controversy, in large part because there are many models to explain observations and few measurements suitable for distinguishing between hypotheses. On October 30, 2007 a magnitude 5.5 earthquake occurred near the Alum Rock springs, California, USA. Within a day we documented a several‐fold increase in discharge. Over the following year, we have monitored a gradual return towards pre‐earthquake properties, but for the largest springs there appears to be a permanent increase in discharge. The Alum Rock springs discharge waters that are a mixture between modern (shallow) meteoric water and old (deep) connate waters expelled by regional transpression. After the earthquake, there was a small and temporary decrease in the fraction of connate water in the largest springs. Accompanying this geochemical change was a small (1–2°C) temperature decrease. Combined with the rapid response, this implies that the increased discharge has a shallow origin. Increased discharge at these springs occurs both for earthquakes that cause static volumetric expansion and for those that cause contraction, supporting models in which dynamic strains are responsible for the subsurface changes that cause flow to increase. We make a quantitative comparison between the observed changes and model predictions for three types of models: (i) a permanent increase in permeability; (ii) an increase in permeability followed by a gradual decrease to its pre‐earthquake value; and (iii) an increase of hydraulic head in the groundwater system discharging at the springs. We show that models in which the permeability of the fracture system feeding the springs increases after the earthquake are in general consistent with the changes in discharge. The postseismic decrease in discharge could either reflect the groundwater system adjusting to the new, higher permeability or a gradual return of permeability to pre‐earthquake values; the available data do not allow us to distinguish between these two scenarios. However, the response of these springs to another earthquake will provide critical constraints on the changes that occur in the subsurface and should permit a test of all three types of models.     

陕西历史博物馆藏东汉绿釉陶孔雀灯的修复

陕西历史博物馆收藏的东汉绿釉陶孔雀灯,1964年出土于陕西省潼关吊桥镇,是一级文物。四川汶川5·12地震致使其在陈列柜内倒翻,断裂为70块碎片,为了能够重新展览该件珍贵文物,必须对其进行修复。本工作在东汉绿釉陶孔雀灯每件碎片（块）的现状调查记录的基础上,通过陶胎和修补材料的XRF、SEM分析,制定了修复方案。采用预加固、清洁、拼对、黏结、补全、补色等措施,完成了复原性修复工作。修复后的东汉绿釉陶孔雀灯已能够达到陈列展出的要求。     

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.     

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.     

南京长江大桥桥头堡抗震加固受力性能研究

为研究南京长江大桥桥头堡填充墙加固对结构抗震性能的影响,提出考虑较高填充墙开裂的双斜撑模型,用于罕遇地震工况下桥头堡的抗震性能计算,同时提出考虑填充墙加固后刚度增强效应的建模方法。利用SAP2000建立了加固前后用于多遇地震工况、设防地震工况及罕遇地震工况的分析模型,并选取了桥头堡在1974年经历的实际地震激励时程及El-Centro地震激励时程作为激励进行了加固前后结构的抗震性能分析比较。研究发现,填充墙加固后桥头堡的抗震性能有了明显提升,其位移响应峰值约下降8%~23%,层间位移角响应峰值约下降12%~22%,而且桥头堡结构在设防地震情况下2个方向的层间位移角均满足了规范要求。另外,在罕遇地震工况下,未加固的填充墙开裂会使结构的扭转刚度下降,而填充墙加固可有效提升结构的扭转刚度,降低桥头堡在地震时发生扭转振动的概率。这2种地震荷载激励的分析结果差异约在3%~21%不等,且响应峰值出现的位置也有一些不同,故对桥头堡进行抗震时程分析时建议选取多条地震波输入综合分析。研究成果可为同类型的钢筋混凝土建筑遗产的抗震加固提供借鉴和参考。     

Historical Survey and Chronology of Bonajuto Chapel in Catania,Italy

Located in the historical center of Catania, Italy, in the Civita district, the Bonajuto Chapel is one of the oldest and best-conserved buildings of the city, which has survived the numerous earthquakes that struck eastern Sicily during the medieval and the modern ages, such as those particularly devastating in 1169 and 1693. However, both the date of this small monument, as well as its original use, still remain uncertain, as literary and documentary evidence are scarce and fragmentary. Most historians, analyzing prevalently the stylistic and constructive aspects, interpreted the chapel as a place of worship and assigned its construction to a rather long period of the early Middle Ages, from the 5th or 6th centuries ad to the 8th or 9th centuries ad—the phase during which the island was under the Byzantine domination. The excavations carried out in 1930 to 1939 and the last restoration works (in 2003) have not provided explicit chronological data. Its age determination is considered essential for a better knowledge of the real influence of this domination on the architecture of the Island. Therefore, a multidisciplinary and accurate analysis of the building using the existing bibliography has been carried out also in order to understand the functional and morphological transformations of the chapel during its long life. The thermoluminescence absolute dating methodology applied to some brickwork elements of the construction, has placed the monument chronology in a period of time that is notably shorter than that previously noted here. These new data, with the study of the architectural structure, have made a significant step forward in the knowledge of the chapel history.     

The ‘Triple R’ Approach on the Restoration of Archaeological Dry Stone City Walls: Procedures and Application to a UNESCO World Heritage Site in Oman

The ‘Triple R’ approach on the restoration of dry stone walls, using recognizable, reversible and respectful constructive techniques is here illustrated. A set of restoration procedures are explained and applied to a UNESCO World Heritage site in Al-Baleed (Salalah, Sultanate of Oman) in the ‘Land of Frankincense’. The procedures were adapted in an innovative way to take into account the climate features of the Indian Ocean area (specifically, the effects of the monsoon season). All the restoration procedures aimed at conserving the site’s original architectural features by using only suitable stones and materials found on-site. Specific procedures have been adopted to consolidate walls, gates, foundations and sloping surfaces. Simple on-site mechanical tests and evaluation methods have been developed for a quick assessment of the safety level of the restored walls to ease future archaeological excavations. The application is related to a waterfront side of the ancient city built around the ninth century and added to over the next five centuries. These restoration procedures allowed for further archaeological excavations with new findings is here described.     

故宫灵沼轩的动力特性及抗震性能研究

故宫灵沼轩是我国最早建造的钢铁-砌体组合结构之一,具有重要的历史、艺术和科学价值。为了评估灵沼轩在地震作用下的结构安全状况,建立了灵沼轩结构的三维有限元模型,并对其进行了动力特性和地震时程分析,得出了其固有频率、模态振型、地震位移响应和地震应力响应。结果表明:灵沼轩整体结构布置对称性较高,扭转刚度较大,对抗震较为有利;在8度多遇地震、设防地震和罕遇地震作用下,灵沼轩的金属结构部分及砌体结构部分的顶点位移和层间位移角均符合现行规范要求,砌体结构部分的第三主应力响应均小于材料的抗压强度,不存在压溃风险。在8度多遇地震和设防地震作用下,砌体结构部分的第一主应力响应均小于材料的抗拉强度,结构不会发生拉裂。但在8度罕遇地震作用下,砌体结构的部分位置拉应力超过材料的抗拉强度,这些位置存在开裂危险。最后,综合动力特性和抗震性能分析的结果,提出了灵沼轩的抗震加固建议。     

Eugenics as Indian removal: sociohistorical processes and the de(con)struction of American Indians in the southeast

Although research on the history of the eugenics movement in the United States is legion, its impact on state policies that identified and defined American Indians has yet to be fully addressed. The exhibit, Our Lives: Comtemporary Life and Identities (ongoing until September 21, 2014) at the National Museum of the American Indian provides a provocative vehicle for examining how eugenics-informed public policy during the first quarter of the twentieth century served to "remove" from official records Native peoples throughout the Southeast. One century after Indian Removal of the antebellum era, Native peoples in the American Southeast provide an important but often overlooked example of how racial policies, this time rooted in eugenics, effected a documentary erasure of Native peoples and communities.