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。     

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。     

Full-Scale Experimental Testing of Retrofitting Techniques in Portuguese “Pombalino” Traditional Timber Frame Walls

Traditional timber frame walls are constructive elements representative of different timber frame buildings, well known as efficient seismic-resistant structures. They were adopted as a seismic-resistant solution in Lisbon’s reconstruction after the 1755 earthquake. To preserve these structures, a better knowledge of their seismic behavior is important and can give indications about possible retrofitting techniques. This article provides a study on possible retrofitting techniques adopting traditional solutions (bolts and steel plates). Static cyclic tests were performed on retrofitted traditional timber frame walls. The experimental results showed the overall good seismic performance of steel plates and the more ductile behavior of bolts retrofitting.     

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。     

武威磨咀子出土木器腐蚀病害与机理分析

武威磨咀子是甘肃古代糟朽木器的重要发现地之一,鉴于北方干燥地区出土的潮湿而糟朽(缺饱和水状态)漆木器与南方潮湿地区出土的浸饱水漆木器之间的差异,致使其保护材料与技术方法不同。本工作通过对武威磨咀子出土木器腐蚀病害与机理分析,着重从病害类型、影响藏品保存因素、材质物理化学组成、材质结构缺陷性及藏品的陈列和保存环境方面进行了全面、综合的科学分析。分析结果表明:武威磨咀子出土糟朽木器腐蚀病害发生是内外因素长期影响和作用的结果,得出保持保存环境的稳定性和控制木质材质中含水量是解决保护问题的关键,可为“十一五”期间甘肃馆藏木器文物实施全面保护修复提供详实的信息和技术支持。     

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.     

明代上洛县主墓出土彩绘木质文物的保护与研究

2007年6—7月,在位于西安市长安县北里王村村东的上洛县主墓中,出土了一批色彩鲜艳的彩绘木俑。因该墓葬曾遭受早期盗扰,出土时木俑较为凌乱摆放在墓室前厅,原来的摆放位置已被扰乱。出土的彩绘木俑均有不同程度的腐朽,其中部分彩绘木俑保存较完整,部分有残缺;整体彩绘保存相对完整,局部有脱落现象。由于长期遭受墓葬环境的影响,所有的彩绘木俑出土时都处于亚饱水状态,而且机械强度较低,没有彩绘或彩绘脱落部位的木胎外观变黄、变脆。这批木俑的木俑颜色鲜艳、姿态各异,不仅具有较高的艺术价值,而且对研究明代民间的宗教信仰,以及葬丧习俗也颇有裨益。为了保护这批珍贵的文物,通过对比试验研究,采用自然脱水法使其脱水定形。使用3％PrimalAC33的水溶液对其彩绘层进行加固保护。同时,在保护处理的过程中,通过显微观察以及一些科学分析手段,对这批木俑的制作方法、装饰材料及工艺进行了初步的探索与研究。     

中国传统建筑营造技艺的整体保护

中国传统建筑营造技艺是以木材为主要建筑材料,以榫卯为木构件的主要结合方法,以模数制为尺度设计和加工生产手段的建筑营造技术体系。营造技艺以师徒之间"言传身教"的方式世代相传。中国传统木结构建筑营造技艺根植于中国特殊的人文与地理环境,是在特定自然环境、建筑材料、技术水平和社会观念等条件下的历史选择,反映了中国人营造合一、道器合一、工艺合一的理念。随着全球化和城市化进程的提速,我国文化遗产的存续受到猛烈冲击,包括营造技艺在内的一些依靠言传身教进行传承的非物质文化遗产正在迅速消失,许多传统技艺濒临消亡,传统建筑营造技艺面临现代建筑思想和建造方式的巨大冲击而目益萎缩,已至濒临失传的境地,加强非物质文化遗产保护刻不容缓。     

上海元代水闸遗址出土木构件无损冻干初探

传统的冷冻脱水过程通常需要将电阻温度传感器(RTD)插入到物料中以监测温度变化从而确定干燥终点,这种方式对于处理木质文物来说具有一定的破坏性,无法做到无损或微损。本研究尝试采用无损方式对定型加固剂浸渍液即时浓度进行分析,并对冷冻干燥终点进行预测。采用这种无损技术成功地对志丹苑元代水闸遗址出土的30件木构件进行真空冷冻脱水定型处理,既达到了预期的定型保护效果,又确保了木构件的安全。     

Seismic vulnerability assessment of historical centers at urban scale

Seismic prevention and mitigation of historical centers have gained a central position within earthquake engineering topics, particularly in areas such as Italy, Greece, and Portugal. Many historical towns in these countries have been strongly damaged, due to the high quantity of old buildings and urban structures and infrastructures. In this article, these aspects are described, modeled, and investigated in terms of structural safety, the goal being the set-up of a comprehensive strategy for seismic prevention and mitigation of a whole historical center. The proposed approach is based on two relevant parts: the first is an urban risk assessment, the second is a prioritization of retrofitting interventions so as to optimally increase urban safety.

The effectiveness of the proposed methodology is shown with reference to a complex case study, the historical center of “Montebello di Bertona”. It is initially modeled as a series/parallel system and then studied by applying seismic reliability methods. Seismic retrofitting interventions are finally prioritized.     

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.     

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.     

Estimating the Seismic Performance of CFRP-Retrofitted RC Beam-Column Connections Using Fiber-Section Analysis

Over the past two decades, many experimental techniques have been developed to improve the efficiency of the externally-bonded fiber-reinforced polymers (FRPs) in order to improve the structural performance of reinforced concrete (RC) beam-column connections. Numerical analysis is also being used as a cost-effective tool to predict the experimental results and to further investigate the parameters that are beyond the scope and capacity of experimental tests. In this study, at first, a fiber-section modeling approach is developed for estimating the seismic behavior of RC beam-column connections before and after application of FRP retrofits. The accuracy of the analysis results were validated against a series of the available experimental data under both monotonic and cyclic loadings. It was pointed out that the proposed model can predict the strength and displacement of un-retrofitted and FRP-retrofitted RC beam-column connections up to the failure points. The verified model was then used to perform a parametric study pertaining to the effect of longitudinal reinforcement ratio on the efficiency of the adopted FRP retrofitting technique to improve the structural behavior of RC beam-column connections.     

志丹苑元代水闸遗址霉菌及防霉剂抑菌效果的再调查与评估

志丹苑元代水闸遗址中处于潮湿环境条件下的木构件经IPBC(碘代丙炔基氨基甲酸酯Iodopropy-nyl Butyl Carbamate)处理已有8年,2012年时测得其细菌总量及真菌总量比2007年分别减少89.25%和55.56%,且木构件中微生物主要类群也在变化。可近年发现IPBC药物的药效在缩短,为了更加有效地治理志丹苑元代水闸遗址饱水木构件上生长的霉菌,对遗址木构件霉菌种类再次进行调查,并对防霉剂IPBC抑菌性能进行再评估。本研究从遗址木构件中分离到8类高丰度霉菌,通过菌落形态特征、培养特性和DNA-ITS序列分析等方法进行菌种的鉴定,发现种类与前几次有明显不同。例如,本次在遗址广泛分布着的一种盘菌科下未分类的菌及绿色木霉都是前几次未曾发现过的。用滤纸片抑菌圈法对这些菌进行IPBC抑菌试验。分析结果发现,木质文物霉菌的防治药物有待升级。     

基于概率法的木构古建筑地震破坏综合评价方法

为了研究木构古建筑地震破坏状态评估的准确性,应用概率的方法,以结构损伤指数、最大层间位移角作为评价因子,建立了地震破坏综合评价模型,提出了基于概率法的木构古建筑地震破坏综合评价方法。该方法在综合现状分析与实验数据,在一定烈度下计算各种破坏状态等级中每一种破坏状态出现的概率,古建筑地震破坏状态应为概率最大的地震破坏状态,从而比较准确地判别木构古建筑地震破坏程度。并对经受过汶川地震的两种结构形式的古建筑进行了验证,从而验证了该方法的合理性和有效性。这一方法将提高木构古建筑震害预测的准确性,为古建筑抗震加固提供有效的理论支持。     

甘肃出土糟朽木器的形态与结构分析

甘肃出土木器依据形态与结构划分,属于典型的糟朽木器类型,材质外观特征与特性明显。制作材质鉴定表明,基本类型有①松科云杉;②松科冷杉;③柏科圆柏。通过对糟朽木器形态类型、结构属性、影响因素及发生改变原因剖析,指出了糟朽木器材质在经历了第一阶段的转折性根本改变后（含水率远低于纤维饱和点）,即将面临第二阶段的转折性根本变化（含水率略高或接近于平衡含水率）,而这一阶段的改变结果对器物将是毁灭性的;为了避免出土器物在短期内形态发生剧变,运用生物切片、扫描电镜分析技术对木质纤维显微结构进行了观察和研究,研究结果与结构病害腐变结果相吻合。选取与糟朽器物同期考古出土的糟朽棺板木作为分析对象,分别对其化学成分、容积重、含水率以及力学性能进行了实验测试,测得糟朽木器降解损失超过50%,含水率约为10.5%,力学强度指标与正常材质相比,均有明显的下降,且相对差异较大,最大约为正常木材强度的60%。对比分析结果,得出了结论：①糟朽木器的形态与结构状况与实验生物切片分析、电镜显微结构观察和研究结果相吻合,同时材质成分、容积重与力学性能测定结果为上述分析结果提供了有力的数据支撑;②致使糟朽木器形态和结构发生改变的主要因素是胎木含水率,其值是非恒定的并随外部环境而改变,因此含水率可用于反映糟朽木器的材质特性;③纤维饱和点与平衡含水率是影响、衡量和评估糟朽木器形态与结构的两个重要的物理参数;④鉴于糟朽木器的材质特性,后期保存应尽量避免与水分的直接接触,需要严格控制其胎木的含水率,且维持恒定、稳定的保存环境,这点对后期糟朽木器的保存是非常重要的     

WHEN SHOULD SEISMIC RETROFITTING OF EXISTING STRUCTURES BE IMPLEMENTED IN ORDER TO MINIMIZE EXPECTED LOSSES

The usual outcomes of the seismic safety analysis for an existing civil engineering structure axe the probability of exceedance of specified limit states and the increase in safety due to retrofitting interventions. This information can be used in several ways. For a single structure, one can compare it with desired target reliability values; for structures belonging to a network, e.g. highway bridges [Donferri et al., 1998], electric networks [Vanzi 1996, 2000) or strategic buildings [Nuti and Vanzi, 1998] they can also be used to assess the priority of interventions.

In this study, an alternative use of the reliability values for existing structures is proposed, which answers the following question: when, i.e. in which year from the date of construction, should seismic retrofitting be implemented so as to minimize the expected total cost? In the expected total cost, here, both the costs of retrofitting and possible disruption, due to delayed retrofitting, are accounted for.

The method proposed computes the expected costs by analysing the branches of the event tree for the problem built after strong but reasonable and highly simplifying assumptions on the problem. Although these assumptions limit the general applicability of the solutions obtained, they allow the building up of an extremely agile and effective solution scheme.

The results obtained from the study, i.e. the year in which it is economically best to implement retrofitting and what the expected annual equivalent cost is, are presented in diagrams and in analytical form, as a function of the most important variables. Finally, an example application on a real structure is presented, which shows all the steps to undertake with the proposed method.     

甘肃武威磨咀子出土汉代彩绘木马颜料 分析与修复保护

武威磨咀子考古出土的汉代彩绘木马,不仅数量多,而且形体较大,具有河西汉马的典型特征;根据彩绘木马的材质状况,其类型属于潮湿而糟朽木器,急需进行修复保护。为此,针对目前彩绘木马的保存现状,本修复工作运用现代X-射线衍射分析技术,对木马彩绘颜料进行了分析,物相结果表明:黑色为墨,白色为石膏,红色为朱砂、铅丹。同时遵循原始制作工艺,选用汉代棺板木作为复原材料对残缺部件进行了复原修复,采用无色、透明的有机玻璃(MMA)材料为其制作了辅助支撑底座,使用Paraloid B-72试剂对表面严重糟朽木质、彩绘层实施加固,使用聚醋酸乙烯酯对脱落部件实施粘接,利用原始铆眼套合与加楔技术对木马部件进行了组装;最后,通过安装辅助支撑底座使受损彩绘木马得到了妥善保护,修复取得良好效果。     

泉州闽台馆馆藏木质类文物的保护处理

福建泉州闽台关系史博物馆多年来收藏的大批木质类文物,不少遭虫蛀和霉菌侵袭。为了不让这些滋生虫菌的文物带到新馆,对这些文物进行了保护处理。先采用溴甲烷常压熏蒸方法杀灭木质文物体内和体表的成虫、虫卵和菌丝。再用软毛刷对木雕文物表面灰尘等物进行小心刷除,然后用水或25%酒精或酒精和丙酮混合液仔细擦拭清洁处理。再用Sparpec 08木材防蛀防腐剂进行渗透处理。保护处理结果表明,本方法技术简单、快捷、易于掌握、实用性强,适用于大批量藏品的杀虫灭菌保护。     

Out of the Peat: Preliminary Geophysical Prospection and Evaluation of the Mid-Holocene Stationary Wooden Fishing Structures in Haapajärvi,Finland

The huge scientific and interpretive value of wetland archaeological sites has been well demonstrated in several studies. The management of the archaeological resource of wetland landscapes is problematic, however, and there is an urgent need for noninvasive techniques to detect waterlogged organic archaeological remains. Stationary wooden fishing structures associated with fishing sites constitute an important wetland archaeological resource in northern Europe. In Finland, similar wooden constructions have been used for fishing from prehistory to the early modern era. The discovery of sites has been accidental, because the waterlogged organic remains have been considered invisible to conventional geoprospection techniques. Because of this, a small project was launched at Lamminoja, northwest Finland, in order to investigate whether it would be possible to improve our chances to detect fishery sites in demanding wetland habitats. New information was obtained through geophysical prospection, trial excavations, and accelerator mass spectrometry (AMS) dating. Geophysical testing was hampered by several factors, including complex sediments affected by modern drainage. New information was obtained, however, on the composition, age, and spatial distribution of the wooden fishing structures preserved in peat over 5000 years.