不同方法加固古建筑榫卯构架抗震试验

为保护古建筑,采用试验方法,研究了不同方法加固榫卯节点后木构架的抗震性能。基于故宫太和殿某开间梁柱节点的具体尺寸,制作了1:8比例的4梁4柱木结构空间框架模型,其中梁和柱考虑为燕尾榫形式连接。采用人工加载方式,进行了低周反复加载试验,研究了马口铁、CFRP布和钢构件加固榫卯节点后对木构架抗震性能的影响。基于试验结果,获得了加固前后构架的力-侧移滞回曲线和骨架曲线,分析了构架耗能能力、刚度退化规律及变形能力,对不同方法加固木构架的抗震效果进行了对比,对其工程应用提出了建议。     

南方地区古建筑木结构的整体性残损点指标研究

古建筑木结构的残损点指标是对古建筑木结构进行结构安全评估和加固修缮设计的重要指标,目前主要依据1992年制定的《古建筑木结构维护与加固技术规范》(GB 50165—92)中的规定,为了对该规范中的构架整体性残损点指标进行验证和补充,本研究通过对南方地区传统的穿斗木构体系和抬梁木构体系的典型榫卯节点和构架的试验研究,得出两种木构体系结构的整体性关键残损点指标,并与GB 50165—92规范进行比较分析。结果表明:规范规定的抬梁式木构架和穿斗式木构架的局部倾斜残损点比试验结果小,规范值偏于安全。规范中规定的抬梁式木构架梁柱榫卯连接残损点略小于试验结果,规范值偏于安全;而规范中规定的穿斗式木构架梁柱榫卯连接残损点对于燕尾榫穿斗木构而言是安全的,但对于透榫穿斗木构而言,则是不安全的。     

青海吾屯下寺民居木构件设计研究

中国传统的木构架建筑,将木材这一主要的结构材料充分运用并将其性能发挥的淋漓尽致,在许多方面可以与现代建筑中的钢筋混凝土材料相媲美。所谓＂木构架＂,就是建筑的结构与骨架,一般由柱、梁、檩、枋、椽以及斗拱等构件组成,这些构件按照一定的模数合理排列布置,构成所要营造的建筑的整体支撑框架,从而起到稳固建筑整体与承托屋顶等部分重量的作用。本文以青海省黄南藏族自治州同仁县吾屯下寺当地木构架民居构建过程中用到的木构件为例,与中国传统木构架中的木构件进行对比研究。     

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。     

试论古建筑木构架类型在历史演进中的关系

文章对现有的理论模式进行反思, 对中国古建筑木构架的几种类型的在历史演进中的关系提出了假说: 从干栏式到地面的穿斗式是木构架自然的发展序列, 具有普遍性。官式建筑的产生和秦汉以来高等级建筑采用井干式与多层木楼阁有关, 并受到穿斗式的影响。抬梁式是官式建筑发展的结果并反过来影响了南北方的民间建筑。     

宁明花山岩画区危岩体稳定研究

花山岩画区的危岩体的存在严重危及古岩画的保存和游客的安全,使得旅游业遭到重创。为了对区内危岩体状态做出评价,并为其后期治理工程提供依据,通过对岩画区的环境地质条件和病害成因的调查,结合危岩体的形态和结构特征,分析得出了区内危岩体崩塌破坏的三种模式为倾倒式崩塌、错断式崩塌和拉裂式崩塌,并提出了不同破坏模式的力学模型。应用极限平衡法对不同破坏模式的危岩体进行了稳定性计算分析,得出区内危岩体大部分处于欠稳定状态,须进行治理。最后提出了危岩体的防治原则与措施。     

秦兵马俑坑防漏设备初探

秦兵马俑坑作为宏大的建筑实体,它不是突兀于地面之上,而是深入地下,以砖、木、席、土为原材料,通过木构架和黄土的结合而形成的一组大型的地下土木建筑群。     

历史建筑木柱防腐措施研究

本工作针对在浙江温州地区历史木构建筑修缮中发现的木柱根部腐朽严重的问题,提出对其的保护措施,分析其腐朽原因。为此,通过查阅相关国内外规范及经验做法、实地调研、勘察检测、实验室进行材料试验、数据统计分析等办法进行综合分析,得出木柱腐朽的主要原因为冷凝水。采用通过对比实验研究发现,传统历史建筑中的木柱础做法和对木柱进行防水处理可以较好地解决木柱腐朽的问题。     

从秦汉骊山汤遗址看汉代单层建筑结构技术

依据秦汉骊山汤遗址,当时一般为单层的居住建筑,大多采用外围承重墙、内为木构架的土木混合结构;但考古也发现有内部木构架、三边夯土墙(带有壁柱)的结构,说明秦汉时期的单层建筑结构形式是多种多样的。     

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。     

Comparison of Numerical and Experimental Seismic Responses of FREI-Supported Un-reinforced Brick Masonry Model Building

Comparative study of numerically and experimentally obtained seismic responses of un-reinforced masonry building supported on in-house designed un-bonded fibre reinforced elastomeric isolator (U-FREI) are presented in this article. The effectiveness of U-FREI is established very clearly in terms of controlled dynamic response of the model building. Experimental studies are carried out on a shake table with elaborate instrumentations for measurement of acceleration and displacements at different floor levels. Numerical study of the model building supported on U-FREI is carried out to compare the results with experimental investigation. Multi-linear pivot hysteretic plasticity model is used to simulate the behavior of FREI, while plate elements are used for brick-masonry walls. Experimentally obtained force-displacement curves of FREI are used for defining the properties of multi-linear model representing FREI. The dynamic responses obtained from the numerical studies are compared with those from experimental investigations. This study indicates that the seismic responses of building supported on U-FREI can be numerically evaluated with quite reasonable accuracy. A good numerical model can be judiciously used at the preliminary design stage, followed by actual testing and construction of the base isolated building.     

Rocking of Non-symmetric Rigid Blocks in Buildings Considering Effects Associated with Dynamic Soil-Structure Interaction

A dynamic model for the estimation of the rocking and/or overturning response of a free-standing non-symmetric rigid block considering rotational and horizontal excitation is proposed. The block is situated at different levels of a building with flexible base subjected to earthquakes. Base flexibility introduces the rotational component of the excitation due to dynamic soil-structure interaction (DSSI). The model is used to assess the influence of the dynamic soil-structure interaction on the behavior of the block. An illustrative example of the proposed model for non-symmetric rigid blocks in 5-, 10-, and 15-story buildings located in soft soils considering earthquakes from different seismic sources is presented. Results show that it is important to consider kinematic effects as well as inertial effects of DSSI in the dynamic response of contents. The influence of base flexibility depends on the change of spectral intensities associated to the increase of the building structural period and is larger for higher building levels.     

故宫灵沼轩残损分析及结构性能研究

故宫灵沼轩是我国最早建造的钢铁-砌体组合结构之一,目前损坏较为严重。为更好地保护和修缮该建筑,残损分析和结构性能研究是其修缮保护的科学基础。首先通过现场调研,对该建筑的残损状况进行分析,找出其显见的病害;然后通过精确测绘、材料检测及有限元模拟分析其结构性能,找出其隐在的病害;最后综合残损分析及结构性能分析结果,提出相应的保护措施建议。     

故宫灵沼轩风振响应分析

故宫灵沼轩是一座砌体结构与钢结构组合而成的文物建筑。为有效对其保护,采用数值模拟方法,研究了风振作用下结构的动力响应。基于灵沼轩结构现状,建立了有限元模型。通过模态分析,获得了灵沼轩的基频和主振型;通过对结构施加y向脉动风荷载,研究了重现期为50年时结构的风振特性,评价了结构在风荷载作用下的安全现状。结果表明:灵沼轩结构基频为f=5.75Hz,在x及y向的主振型以局部振动为主;脉动风压作用下,结构保持稳定振动状态,但顶部位置加速度峰值偏大。另风压作用下,砌体结构部分位置的抗拉强度不足,应在日常维护中予以重视;钢结构部分由于材料强度大,因而不会出现强度破坏。     

Lessons Learned from Seismic Analysis of a Seven-Story Concrete Test Building

A uniaxial shake table test of a full-scale slice of a seven-story reinforced concrete wall building was performed at the University of California, San Diego. A 2D analytical model that primarily employed fiber-based beam-column elements was used for a blind prediction of the global response of the building to the imposed input accelerations. An improved analytical model, which adequately simulates the building's dynamic response and comparison of measured and analytical results, is presented. The lessons learned from participation in the blind prediction with particular attention to the effects of issues commonly ignored in analytical modeling of concrete buildings are included.     

单檐歇山式木构古建抵抗极端烈度地震试验调查研究

为更好地保护我国古建筑,基于《单檐歇山式古建筑抗震性能振动台试验》的相关成果,研究了强震作用下我国明清官式木构古建的抗震性能,制作了与该论文相同的试验模型,进行了振动台试验。通过对模型输入烈度逐渐增强的1940年El-centro波,并考虑地震波为水平双向作用,分析了强震作用下不同构造的试验现象,开展了详细的震后调查,获得了不同构造在强震作用下的抗震性能和震害机制。结果表明:强震作用下,我国明清官式木构古建的振动形式表现为柱架、斗拱、梁架及屋顶的近似同步往复摇摆;主要震害包括柱底偏移、榫卯节点开裂、拔榫、斗拱偏移及错位、额枋-垫板分离、墙体倒塌等,但承重木构架受损不严重,结构未产生倒塌。其良好抗震性能的原因与古建筑的构造特征密切相关。     

ON THE SEISMIC VULNERABILITY OF EXISTING UNREINFORCED MASONRY BUILDINGS

A large part of the building population in Switzerland is made of unreinforced masonry. For the assessment of the seismic risk the evaluation of the seismic vulnerability of existing unreinforced masonry buildings is therefore crucial. In this paper a method to evaluate existing buildings, which was developed for the earthquake scenario project for Switzerland, is briefly introduced and discussed in more detail for unreinforced masonry buildings. The method is based on a non-linear static approach where the seismic demand on the building is compared with the capacity of the building. In-plane and out-of-plane behaviour are considered. Comparisons with test results from model buildings show that the proposed method suitably forecasts the capacity of a building. Finally, a numerical example of the application of the method to a building in the city of Basel is given.     

Effect of AAC Infill Walls on Structural System Dynamics of a Concrete Building

The effect of autoclaved aerated concrete (AAC) infill walls on the structural system dynamics of a two-story reinforced concrete building is investigated using its finite element structural model, which is calibrated to simulate the acceleration-frequency response curves from its forced vibration test. The model incorporating the AAC infill walls by equivalent diagonal struts captures the increase in lateral stiffness of the building and the torsional motions induced due to the asymmetrically placed AAC infill walls. A higher strut width coefficient than in ASCE/SEI 41-06 is recommended to model the stiffness of the AAC infill walls in the elastic range.     

Seismic Performance and Modeling of a Half-Scale Base-Isolated Wood Frame Building

The concept of base isolation is a century old, but application to civil engineering structures has only occurred over the last several decades. Application to light-frame wood buildings in North America has been virtually non existent with one notable exception. This article quantitatively examines issues associated with application of base isolation in light-frame wood building systems including: (1) constructability issues related to ensuring sufficient in-plane floor diaphragm stiffness to transfer shear from the superstructure to the isolation system; (2) evaluation of experimental seismic performance of a half-scale base-isolated light-frame wood building; and (3) development of a displacement–based seismic design method and numerical model and their comparison with experimental results. The results of the study demonstrate that friction pendulum system (FPS) bearings offer a technically viable passive seismic protection system for light-frame wood buildings in high seismic zones. Specifically, the amount and method of stiffening the floor diaphragm is not unreasonable, given that the inter-story drift and accelerations at the upper level of the tested building were very low, thus resulting in the expectation of virtually no structural, non structural, or contents damage in low-rise wood frame buildings. The nonlinear dynamic model was able to replicate both the isolation layer and superstructure movement with good accuracy. The displacement-based design method was proven to be a viable tool to estimate the inter-story drift of the superstructure. These tools further underscore the potential of applying base isolation systems for application to North America's largest building type.     

Understanding Local Leadership in Building the Capacity of Rural Communities in Australia

Current approaches to rural community development in Australia provide for limited government intervention. Such intervention is usually housed within programmes that seek to build the internal capacity of communities to achieve long term socio‐economic sustainability. A fundamental implementation strategy for capacity building has been developing local leadership. The underlying assumption of this approach is that good leadership will result in existing resources being mobilised for a more sustainable function and new resources attracted. What though is good leadership in terms of building the capacity of rural communities to develop sustainable socio‐economic futures? This paper compares the conceptualisation of leadership within rural development policies and leadership training programmes with the nature of local leadership as it exists in on‐ground community building projects. From an in‐depth review of the role and nature of local leadership within six Australian rural communities it was found that local leadership could result in improved adaptive capacity if the leadership is similar in nature to Burn's (1978 ) transformational model of leadership. Within policy, local leadership was most often conceptualised as being similar to this transformational model. However, rural leadership training programmes tended to conceptualise leadership as a top‐down process, similar to Burn's (1978 ) transactional model. While this study of leadership within rural communities revealed that transactional skills, as taught in leadership training programmes, were important for successful project management, such skills did not necessarily result in improved community adaptive capacity. It is suggested that, while transactional leadership can have an important role in influencing the development of rural communities, greater attention needs to be given to developing strategies to support transformational leadership.