明清古建筑木结构典型抗震构造问题研究

为保护古建筑,采用分类统计方法,研究了我国明清古建筑木结构的典型抗震构造问题。基于大量工程现场勘查结果,对古建筑木结构的典型抗震构造问题进行了归纳汇总,分析了原因,提出了加固建议;基于典型算例,对古建筑木结构加固方法进行了深入论证。结果表明:我国古建筑木结构的柱子、斗棋、榫卯节点、梁架、屋顶等各部位都容易产生开裂、糟朽、变形、拔榫等抗震构造问题并影响结构的抗震性能,而这些问题的产生原因主要与木结构的构造特征、木材材料性质及施工保养等因素有关;对这些抗震构造问题及时采取合理有效的加固措施,可减轻或避免结构产生的震害。     

Seismic Retrofitting Techniques for Historic Adobe Buildings

This article presents a comprehensive overview of the techniques available for the seismic retrofitting of adobe buildings. It analyzes these techniques’ viability from a structural engineering standpoint and evaluates their suitability in the context of historic preservation. Analysis was based on an exhaustive review of studies addressing retrofitting techniques of earthen structures, as well as consultation with field experts. The guiding principles of conservation relating to the structural reinforcement of monuments were taken into account. Traditional techniques that enhance the stability of the building, such as wooden ring beams, wooden ties interconnecting parallel walls, corner keys, and the addition of buttresses were found to be effective solutions since they employ compatible and low-cost materials such as earth and wood. When these techniques prove insufficient, minimally invasive measures such as introducing a plywood diaphragm, horizontal steel rods, a geomesh covered with mud rendering or a strapping system can be appropriate.     

甘肃出土糟朽木器材质鉴定及特征分析

甘肃木器是反映河西走廊古丝绸之路文化、历史和社会重要的珍贵遗产。武威、高台作为甘肃木器重要的发现地,出土器物不仅类型、风格迥异,而且器物材质形态、结构特征明显,属于典型的糟朽木器类型。研究工作从木材学的角度出发,应用生物切片技术,对出土器物材质树种、特征及特性进行了科学鉴定和剖析。鉴定结果表明,树种类型有:①云杉;②冷杉;③圆柏;④落叶松;⑤胡杨;⑥榆树;⑦香椿;同时采用扫描电镜、X射线衍射分析技术对糟朽木质纤维显微形态、结构进行了观察和分析,分析结果表明:出土糟朽木器木质结构已发生降解、腐变,其材质形态特征及特性会随着后期保存环境及其因素的影响、腐蚀而频繁变化或骤变。最后,分析工作对糟朽木器纤维素结晶度、降解度等相关物理参数进行了实验测定。测定结果表明:出土实物纤维素结晶度约为58%,而纤维降解度达到40%以上。综合以上鉴定结果和实验数据,得出以下结论:①甘肃木器制作材质涉及的树种种类较多,基本以云杉材为主,而青海云杉在祁连山林区分布广泛,为其制作用材提供了丰富的天然材料;②材质糟朽及纤维严重降解是甘肃木器重要的材质特征,表现为纤维(纤维素、半纤维素)含量降低呈现木素含量升高,而木素含量的相对增大,则是导致材质颜色变深的重要原因;③受糟朽器物自身含水率的变化、影响,其材质特征具有脆弱性和不稳定性,而且改变、变化过程通常具有滞后性,导致结果往往是致命的;④纤维素结晶度和纤维降解度是衡量和评估糟朽木器材质健康状况重要的物理参数,二者之间存在关联关系。本研究结果可为糟朽木器形态与结构研究提供科学依据和技术支撑。     

Wood deterioration in Chacoan great houses of the southwestern United States

Abstract

‘Great houses’ built by the Ancestral Puebloans (Anasazi) (900–1200AD) still contain thousands of pieces of wood used as beams, secondary roof supports and lintels. The wood is an integral part of the surviving Chacoan architecture and has served as a valuable resource for determining the exact age of the structures and for obtaining information about raw material production, procurement and harvesting methods. An assessment of wood deterioration at the great houses in Aztec Ruins National Monument and Pueblo Bonito, Pueblo del Arroyo and Chetro Ked located in Chaco Culture National Historic Park in New Mexico have revealed that both microbial and non-biological deterioration was taking place. The major type of decay found throughout the structures was caused by soft-rot fungi. Cavity formation in secondary walls of conifer woods and an erosion of cell walls in aspen woods was prevalent. A brown-rot type of wood degradation was also found, primarily associated with areas of subterranean termite damage. Another form of deterioration present in some of the woods was a chemical de fibration of wood. This corrosive attack, caused by high concentrations of salts, destroyed the middle lamella between cells, resulting in a stringy mass of loosely attached fibres. Reburial of great house structures as an effective conservation strategy will require an environment that is not conducive to decay, since active wood-destroying fungi are present in the prehistoric woods. If moisture and other conditions suitable for decay exist, the wood will be destroyed and this important historical resource lost.     

四川九寨沟县中查村传统村落的遗产价值及保护研究

九寨沟中查村作为第四批中国传统村落,面临的威胁远大于其他少数民族传统村落,通过田野调查总结出其六大建筑特征,作为九寨沟片区安多藏族民居的基础研究成果。同时,在对中查传统村落濒危民居调研的基础上,揭示村落保护需要以"人"为本,从生存基础建设、社会关系建设、精神场所建设的三个维度来探索,这是从产业到社区,再到文化建设的一个动态过程,为中国西南少数民族地区传统村落保护提供切实可行的理论依据和发展思路。     

慈利白公城遗址出土木材种属的鉴定研究

慈利白公城遗址历史悠久,具有重要的考古价值。该遗址出土了大量木质井壁及少量其他木质文物,为了解这些木材的特点,以及为木材保护提供相关的参考,通过徒手切片,并利用光学显微镜对该遗址出土的10件木质样品进行鉴定。结果表明其中1件为无患子(Sapindus. mukorossi Gaertn.),1件为冷杉(Abies fabri(Mast.)Craib),2件为湖南杨桐(Adinandra. acutifolia Hand.-Mazz.),2件为香椿(Toona sinensis A. Juss.),4件为润楠(Machilus pingii Cheng ex Yang)。通过实验结果,初步推测井壁的制作在当时是比较重要的工作,此时已经在选择性地使用木质井壁原料。从树种适宜生长的环境上看,同时期该遗址附近可能是以阔叶材为主的针阔叶混交林,气候温暖湿润。     

Dendrochronological analysis of bowed and plucked instruments from the San Pietro a Majella Conservatory,Naples

The Museo Storico Musicale of the San Pietro a Majella Conservatory of Music in Naples owns a collection of over 200 musical instruments of considerable historical importance. Within the collection, 30 bowed and plucked instruments representative of the Neapolitan violin-making tradition were analysed dendrochronologically to date them, estimate the provenance of the wood and investigate the instruments’ construction characteristics. The values of the statistical cross-dating tests were generally high and allowed 26 instruments to be dated. In all but one case, the dates were consistent with those of the catalogue. From the perspective of wood selection, we noted an unusual use of very old spruce wood, well beyond simple seasoning. The construction technique of the soundboard and other characteristics show good similarities with instruments analysed in other Italian collections. Thus, even in Neapolitan instruments, the growth rings are smaller in small instruments and larger in cellos or double basses. In conclusion, the Neapolitan violin-making school has shown great care in the choice of wood, most coming from regions as far away as Germany or Switzerland, thus confirming the existence of an active large-scale trade in wood for the production of musical instruments.     

故宫古建筑结构可靠性问题研究

为保护故宫古建筑,采用归类汇总与理论分析相结合的方法,研究了故宫古建筑木结构的典型残损问题。基于大量现场勘查及理论分析结果,对故宫古建筑存在的典型可靠性问题进行了分类汇总,分析了产生这些问题的原因,提出了可行性加固建议。通过典型算例,对古建筑木结构加固方法进行了深入论证。结果表明:故宫古建筑木结构的柱子、斗栱、榫卯节点、梁架、屋顶、墙体等各部位都容易产生开裂、糟朽、变形、拔榫等可靠性问题并影响结构整体的稳定性能,而这些问题的产生原因主要与木结构的构造特征、木材材料性质及施工保养等因素有关;针对不同的可靠性问题,采取合理有效的加固方法,可提高古建筑结构整体的稳定性能。     

木雕文物的褐腐菌害

为对一尊唐代木雕佛像严重朽蚀的原因进行调查,用扫描电镜观察,对样品的综纤维素、木质素含量等进行分析测定,并对菌进行培养。实验结果表明,木材纤维中有菌丝,真菌孢子,经一定温湿度培养后,腐朽木材上的孢子有发展,说明该真菌在原介质上存活,在合适的环境条件下,将会继续起菌害作用。分析数据说明,综纤维素含量大大降低,木质素的相对百分比含量大大升高,这是综纤维素及其相伴生的戊聚糖受真菌破坏分解的结果。此等菌害的表现应该是属褐腐菌对木材破坏的结果。由于褐腐菌对木材短时间内就能产生强大的破坏力,因此,对木质物的保护要特别重视褐腐菌的侵害。     

再论高句丽山城城墙内侧柱洞的功能

本文通过对近年来韩国境内高句丽山城发现土柱洞的分析,比较其与我国境内高句丽山城石柱洞的不同,指出其主要功能为在堡垒等小型军事据点外缘树立木制城栅,起到类似城墙的作用。采用木栅替代城墙因其构筑快速,适应战争形势的变化,而并非受制于技术的落后。土柱洞的出现可视为衡量高句丽晚期山城的一项指标。     

Dendrochronology and archival texts: Dating the Ottoman fortress of Seddülbahir on the Gallipoli Peninsula,Turkey*

This paper provides the results of the dendrochronological analyses of seven wood samples from the Ottoman fortress of Seddülbahir on the Gallipoli Peninsula or Turkey. It concludes that the trees were cut in the late spring of 1656. The data collected allows the first building phase of the fortress to be securely dated. By bringing together the dendrochronological results with various archival records about the fortress, a more precise building chronology for the fortress can be reconstructed. The probable initial period of construction was between 1656 and 1661.     

天然树脂加固淹埋木质文物

为了对剑川海门口遗址出土的古思茅松进行实验性加固保护,对古思茅松进行草酸脱色、甲醇溶剂脱水,然后使用松香和虫胶的甲醇溶液作为加固剂进行渗透、干燥等加固工序。加固后的样品表面色泽浅淡,保持了木材原有的色泽、纹理和质感。基本密度达到0.437g/cm3,已接近现代木材的基本密度。顺纹抗压强度较加固前增加了24.58%。绝干状态时测得的各向全干收缩率分别为:纵向2.22%、径向3.54%、弦向7.73%,均在正常木材干缩变化范围之内。扫描电子显微镜(SEM)研究表明:天然树脂附着在细胞壁表面,对细胞壁起到了足够的支撑作用,加固后的木材细胞壁切面平整、致密、轮廓清晰,胞壁间界面结合好,细胞腔较光滑。研究表明,本加固方法能有效降低木质文物的吸湿性、提高其各项物理力学性质。当木质文物需做其它处理时只需用甲醇或乙醇将松香和虫胶溶出即可,加固过程可逆,这解决了木质文物将来的再处理问题。     

Application of Non-Destructive Techniques in the Inspection of Wooden Structures of Protected Buildings: The Case of Nuestra Señora de los Dolores Church (Isla Cristina,Huelva)

This study describes a thorough inspection of a 20th century church in the town of Isla Cristina (in the province of Huelva, southwestern Spain), which is currently awaiting restoration. The study indicates the damage processes at work in the building structure materials (brick, concrete, steel, and wood), which are closely related to its geographical location, and analyses the deterioration of the wooden roof structure. The analysis of the wooden roof includes the results of an inspection methodology on a protected building based on traditional techniques such as visual inspection and innovative non-destructive inspection techniques (visual classification, ultrasounds and thermography). Fieldwork consisted of the visual classification of the wooden pieces according to Spanish standard UNE 56544:2007 specifications after which ultrasound and thermography techniques were applied on-site. A second stage involved laboratory tests (anatomic identification, density and bending strength) using wood samples extracted from the structure in order to check the values for the physical and mechanical properties previously recorded by non-destructive techniques (NDT). These non-destructive techniques are used in inspections of the wooden roofs of buildings to identify dampness, deterioration, density loss and defects as a means of assessing their conservation status. This work concludes that the use of ultrasound and thermography techniques constitute an accurate diagnostic tool for the on-site inspection of wooden structures and the evaluation of their condition. Thermography identifies different materials and moisture content while ultrasound detects the various degrees of deterioration and density-loss in areas of the wood with high moisture content.     

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.     

Dating of 4th millennium BC pile-dwellings on Ljubljansko barje,Slovenia

We present absolute dates of seven late Neolithic pile-dwellings on Ljubljansko barje, Slovenia. They were settled from ca. 3600 to 3332 (±10) and from 3160 to 3071 (±14) cal BC, as shown by investigations of wood using dendrochronology and radiocarbon wiggle-matching. We defined eleven periods of intensive tree felling (and building activities) and one major settlement gap (when no trees were felled) from 3332 to 3160 cal BC. A major settlement gap presumably also followed after 3071 cal BC (i.e., after the end date of the investigated sites). Our investigations included over 2500 pieces of wood, mainly from the piles on which the dwellings were built. Among important wooden artefacts were a wheel with axle (one of the oldest preserved wheels in the world) and two dugout canoes, all from the settlement phase from 3160 to 3100 cal BC. As shown by parallel studies, the economy in the sites was characterized by copper metallurgy, skilful wood processing and use, cultivation of domestic plants, gathering of wild plants, animal husbandry, hunting and fishing. The settlements were contemporaneous with a number of sites in the north of the Alps, the younger ones coincided with the lifetime of the Neolithic Iceman (Ötzi). Since Ljubljansko barje has a strategic position at the crossroads between western central and (south) eastern Europe the presented absolute dates provide a basis for their comparison with other dated contemporaneous sites (in the west), to revise the chronology of similar sites in the (south) east (which are not yet exactly dated), and to evaluate their interconnection and roles in cultural development in prehistory.     

越南境内汉墓出土院落明器研究

越南境内院落明器在东汉中期开始出现并延续至三国初年,院落的主体房屋由平地式演变为干栏式,院落的布局由前庭后屋式结构演变为房屋三面环绕中庭的结构。越南境内汉墓出土的院落明器在干栏式结构和城堡式设计方面既受到两广地区汉代典型建筑明器的影响又形成了自身的地域特点,此外以天井为中心的院落平面布局以及房屋独特的制作技法也体现了鲜明的本地特色,东汉晚期至三国初年具有越南境内地区特色的院落明器直接输出到两广地区,上述文化交流现象产生的原因与东汉时期两地密切联系的历史背景有关。     

Thin-folded Shell for the Renewal of Existing Wooden Roofs

In this article, a technique for the renewal of historic building wooden roofs is presented. The solution can be used for the strengthening of existing wooden roofs against excessive lateral thrusts on the peripheral wall or for the recovery of the attics, as it allows removing the existing structural elements, such as possible wooden truss-works of no artistic value. With minor adaptations, the solution can be addressed to enhance the building seismic performance. The technique is minimally impairing on existing buildings and can be applied also in new constructions.

The technique is based on the construction of a thin folded shell, overlaying the existing pitches. Emphasis is given to lightweight folded shells, obtained by overlaying thin plywood panels on the existing roof rafters and planks, without modifying the overall architectural layout.

The technique conceptual design is discussed and a simplified analytical method is proposed, which allows for the clarification of the role of each structural component and can be adopted for the folded shell proportioning and design. The analytical results are validated against numerical results obtained with reference to some case studies. Ultimately, emphasis is given to the detailing, whose correct execution is mandatory for the success of the proposed structural intervention.     

Two wooden coffins from the Shakhoura Necropolis, Bahrain

This article presents a detailed analysis of two wooden coffins from the 1^st centuries BC/AD on Bahrain. New C14 dates are published of samples taken from the coffins, and their method of manufacture is reconstructed. The unexpected conservation of wood in a humid environment like Bahrain is explained.     

On-site Radioscopic Qualitative Assessment of Historic Timber Structures: Identification and Mapping of Biological Deterioration of Wood

The recent development of portable, battery-charged x-ray tubes and digital detectors has made digital radioscopic examination of wooden buildings a realistic option. Lack of experience with the often very complex radiographs of building structures makes the interpretation of such radiographs difficult. A set of radiographs of wood in different, identified conditions was established for use when interpreting radiographs of wood in unknown condition.

This article presents radiographs of a trestle-framed building. The recordings were done in areas where the condition of the wooden elements was known in advance, either on the basis of dendrochronological drill samples or because the building element had been replaced recently and the wood was sound. The radiographs were compared with NIKU´s collected guideline radiographs and discussed with respect to the information they provide about the wood’s condition. Finally, we discuss radioscopy as a supplement to traditional methods of building surveying.

The authors took all of the photos and radiographs (©NIKU). The radiographs are shown as “shadow” images—materials of higher density are seen lighter than materials of less density, as long as they are of same thickness.     

The Shell-Implements and Other Antiquities of Barbados

Reconsideration of the evidence set out by Jackson and Fletcher in 1962 shows that it does not lead uniquely and inevitably to the complicated building history postulated by them for the apsidal chancel at Wing, whereby the present walls were supposed to have arisen in part by cutting back earlier alignments and in part by building them forward and inserting the pilaster strips. Instead it is shown that all the known evidence can be interpreted in terms of a simpler and more plausible building sequence in which the present walls of the apse arose in a single building operation which included the pilaster-strips and arcading as well as the internal plaster which separates the original walls of the crypt and apsidal chancel from the later stone vaulting of the crypt. This revised interpretation does not affect the important conclusion that the walls of the polygonal apse were built later than the main walls of the nave; but this conclusion is based upon simpler direct observation. Unfortunately the evidence at present available does not allow precise details of the building phases to be stated with certainty; a new thorough archaeological investigation would be needed to settle these questions and to provide an indication of the dates of the several phases.