Temperature effect on the structural strains of an ancient Tibetan building based on long-term monitoring data

Many studies have indicated that structural strain will be significantly influenced by temperature variations,and a good understanding of the effect of temperature on structural strain is essential.A structural health monitoring system has been installed in a typical Tibetan timber building to measure the structural strains and ambient temperature since 2012.This paper presents the correlation between temperature and strain data from the monitored structure.A method combining singular spectrum analysis and polynomial regression is proposed for modeling the temperature induced strains in the structure.Singular spectrum analysis is applied to smooth the temperature data,and the correlation between the resulting temperature time series and the measured strains is obtained by polynomial regression.Parameters of the singular spectrum analysis and the regression model are selected to have the least regression error.Results show that the proposed method has both good reproduction and prediction capabilities for temperature induced strains,and that the method is accurate and effective for eliminating the effect of temperature from the measured strain.A standardized Novelty Index based on the residual strain is also used for the condition assessment of the structure.

Study on the Protection and Renovation of Ancient Buildings in Likeng

As a famous historical and cultural city of China, and one of the ecological conservation experimental plots of Huizhou culture, Likeng owns many cultural units under state and local protection. The paper elaborated the significance and principles of protecting ancient buildings in Likeng, analyzed the restoration principles and technical schemes. Through analyzing the protection of ancient buildings in Likeng, the rationality of protection, and the balance between protection and development was proposed, and protection of the projects in the national historic and cultural heritage list, cultural relics protection units at all levels, famous historic and cultural cities was introduced.

Combustion Properties of Textiles Applied in Tibet Ancient Buildings and Their Clean Flame Retarding Designs

In the Tibet ancient buildings, there are large amounts of combustible decorative textiles that pose great potential fire hazards. Some typical textile samples were collected from the Potala Palace. Their combustion properties were analyzed by UL 94 Vertical Burning test and Limiting Oxygen Index test. The effects of plateau climate on combustion properties, an important fact required to be considered in the flame retarding design for combustible textiles, were preliminarily compared via test data in the plain and those in the plateau. Based on the foregoing analyses, some thoughts were presented on the clean and feasible flame retarding means for the decorative textiles due to their special applications in Tibet, in ancient buildings and in plateau climate. The fire resistance, weather resistance, UV resistance, endurance, ornamentation and religious performances for these textiles must be taken into considerations comprehensively in the designs.

Study on the Lightning-Protection of Ancient Buildings

By reviewing ancient buildings that were destroyed by lightning strike or fire caused by lightning,lightning protection of ancient buildings was discussed,ancient architectural complex in Dagu Mountain,a provincial-level scenic area of Liaoning,was taken for an example to detect potential safety hazards in lightning-protection of those ancient buildings,5 types of potential safety hazards were summarized.By studying the classification of ancient buildings' lightning-protection,protection level,lightning-protection measures,design basis of lightning-protection engineering,construction and new construction technology,relevant technical specifications were taken as references for proposing 4 countermeasures against those potential safety hazards from the perspectives of exterior and interior parts of ancient buildings,lightning-protection of ancient trees and so on.In view of actual conditions of the ancient architectural complex in Dagu Mountain,construction plan,personnel placement,labor planning,construction quality control system,acceptance of works,technical documentation and such matters were specifically discussed to give useful support to the future lightning-protection of ancient buildings.

Application of Three-dimensional Laser Scanning Technology in the Teaching Practice of Surveying and Mapping of Ancient Buildings

Based on the study of the application of three-dimensional laser scanning technology in ancient building surveying and mapping,this paper briefly describes the working principle and flow of three-dimensional laser scanning technology.Based on the practical application,this paper puts forward the discussion of related problems and matters needing attention.This has a certain reference significance for the study of new technology in surveying and mapping of ancient buildings.

Architectural Features of Stilted Buildings of the Tujia People: A Case Study of Ancient Buildings in the Peng Family Village in Western Hubei Province, China

This paper describes and analyzes the stilted buildings of the Tujia people (an ethnic group living in China's Mainland), a distinctive building style unique to them, from the perspectives of site selection, spatial layout, construction techniques, and cultural inheritance. The cluster of stilted buildings (Diaojiao Lou in Mandarin Pinyin) in the Pengjia Village (meaning most of the villagers share the surname of Peng) is presented as a case study in this paper. The paper makes a case for their preservation as authentic carriers of the Tujia people’s cultural history, which is quickly disappearing due to development pressures. Three preservation strategies are discussed to meet this preservation goal. The first is to provide a detail analysis of the construction language to guarantee authenticity in the documentation, preservation and restoration processes of the stilted buildings. The second is to keep alive the expert knowledge and skill of traditional artisans by involving them in the construction of new structures using diaojiaolou techniques. The third strategy is to encourage local people to “dress-up” discordant buildings constructed mid to late 20th century with well-mannered facades using traditional details such as suspension columns, shuaqi, and six-panel and bang doors. Taking as a whole, these strategies are presented to help local residents, preservation experts, developers and policy makers sustain the irreplaceable cultural heritage and economic independence of the Tujia people.

Wudang Ancient Buildings

THE palaces and temples of the ancient building complex in the Wudang Mountains exemplify the architectural and artistic achievements of China＇s secular and religious buildings of the Yuan （1279-1368）. Ming （1368- 1644） and Qing （1644-1911） dynasties. Towering mountains and deep valleys are partnered with nearby woods, rocks and streams, presenting a harmonious picturesque fusion of man-made architecture and nature.

A Review of Applied Methods of Using Solar Energy in Iranian Buildings

Solar energy is the radiant light and heat from the Sun that has been harnessed by human since ancient times. Also secondary solar resources such as wind and wave power, hydroelectric power and biomass account for most of the available renewable energy on Earth, which can be used by human. Architects since alacient times have used various methods to hamesse and employ the solar energy for lighting, cooling and heating and etc. Meanwhile, Iran＇s ancient architecture, as an adaptive one, which consists of various climatic reigns, is filled with abounding examples of using sun energy in buildings. But, unfortunately despite these ancient methods, our modern architects mostly tend to provide energy of buildings with fossil fuels. This increases energy costs of the building＇s and also pollutes the environment. In this article it is intended to consider the ancient ways of using solar energy in Iran, and then suggest new methods for applying in modem buildings. The results of consideration show that among Solar technologies, passive and active methods, Iran＇s ancient architects have used passive methods, for example in mass and space, orientation and settlement of building. The idea of passive methods can be used in new shapes in current buildings, for instance by using solar space, central yard and etc. The suggestive method in this paper is combining the passive methods with the active ones.

古建筑木构件开裂机制、评估与加固研究进展

开裂作为古建筑木构件最常见的残损类型之一,影响木构件的长期服役性能,是古建筑稳定性与安全性评估的重要考查内容。本文从古建筑木构件开裂情况、原因、影响,评估方法及修复加固等方面,系统梳理古建筑木构件开裂残损相关研究成果。分析发现我国古建筑木构件开裂的主要原因为木材干缩与受力破坏,主要类型为纵向开裂,开裂可降低木构件力学性能,也可为其他不利因素作用于木构件提供条件。目前主要通过实际试验与数值模拟评估开裂对木构件性能的影响,利用金属材料、纤维增强复合材料(fiber reinforced polymer,FRP)与高分子树脂材料对开裂木构件进行修复加固。然而,由于古建筑的特殊性与木材变异性,仍需进一步探索木构件的不同尺度开裂机制,开发适用于古建筑开裂木构件的检测、评估与加固方法,建立科学系统性的古建筑保护体系。

古建筑火灾风险智能孪生评估方法研究

为实现有效的古建筑灾害预防和应急处置决策,采用“数据-处理-业务-服务”的多层次框架,与贝叶斯网络和K-Means聚类算法(BN-KM算法),基于数字孪生模型建立1种古建筑(群)火灾风险评估及决策建议的智能方法,通过8地古建筑火灾历史案例验证该模型的多区域适用性(准确率为87.50%),通过G古建筑(群)4个时段的火灾风险演化规律,验证该方法的时间动态适用性。研究结果表明:该方法中多层次框架可实现多源异构数据(历史数据、监测数据等)的集成量化和风险评估的秒级运算,孪生方法可在事故发生或未造成重要损失前进行计算推演得到高风险区域,并针对不同对象(决策者、救援者、公众)提供专业服务,本文描述新智能方法的评估和决策建议流程,该方法论可拓展应用至其他灾害场景(地震等)。研究结果可为古建筑灾害预防和应急处置提供意见支持。

出踩与面宽方向柱头科斗栱抗震性能对比试验及数值分析

为研究加载方向对斗栱抗震性能的影响,文章基于地震作用的随机性和斗栱出踩与面宽方向的构造差异,对2个足尺柱头科斗栱分别沿出踩和面宽方向进行拟静力试验,得到斗栱的破坏模式、承载力、刚度与强度退化、耗能和变形能力。结果表明:斗栱在出踩和面宽方向分别加载时,大斗均相对平板枋滑移,馒头榫挤压剪断。出踩方向受力时单昂与桃尖梁相对滑移,面宽方向受力时整体明显转动。相比面宽方向受力的斗栱,出踩方向受力的斗栱具有更高的承载力、初始刚度和耗能能力,而变形能力较差。文章开展柱头科斗栱的数值分析,模拟结果与试验结果吻合较好,研究出踩和面宽不同加载方向、轴压荷载、木构件之间摩擦系数和木材弹性模量对其抗震性能的影响。结果表明:面宽方向是柱头科斗栱的最不利受力方向,其正负向承载力比出踩方向分别低19.21%和17.03%;轴压荷载和木构件之间摩擦系数越大,斗栱承载力越大,而木材顺纹弹性模量和横纹径向弹性模量对斗栱的初始刚度和承载力影响较小。

基于DIC古建筑青砖受冻融循环作用的损伤演化

以内蒙古隆盛庄古建筑青砖砌体为研究对象,通过数字图像相关(DIC)技术,研究古建筑青砖在冻融循环作用下的损伤破坏规律,采用双因子——损伤程度因子和损伤局部化因子来表征古建筑青砖的单轴压缩损伤过程,并根据双因子损伤演化曲线建立了不同冻融循环次数下的损伤演化模型.结果表明:古建筑青砖在单轴压缩下的破坏过程可分为初始损伤闭合阶段、线弹性损伤阶段、弹塑性损伤阶段和塑性损伤阶段4个阶段;随着冻融循环次数的增加,青砖表面应变集中程度增大,使其承载能力降低;冻融循环会缩短双因子曲线的线弹性阶段,同时利用双因子建立的损伤演化模型能有效反映冻融循环作用下古建筑青砖材料的损伤演化过程.

结构健康监测系统在木结构古建筑中的应用

文物木结构古建筑是一个国家文化的重要组成部分,代表着民族文化的自信与传承。然而由于长时间受到环境和人为侵蚀,木结构古建筑易遭到损坏。为更好地保存好木结构古建筑以及其代表的文化内涵,对其结构安全监测提出了迫切的需求,近年来对木结构古建筑的安全监测方法也得到了快速的发展。分别介绍了虚拟重建、红外热成像、地面激光雷达、超声波监测、光纤传感等技术的原理及在木结构古建筑监测中的应用,并总结了其各自的优势与劣势。针对木结构古建筑采光不足问题,总结了光导系统,尤其是光纤光导照明系统对自然光的引入,该类照明系统具有清洁、安全的特点,避免了烛火、电类照明系统为木结构古建筑带来的火灾风险。

歪闪古建木构架整体纠偏方法与数值模拟

由于环境与人为等因素的长期影响,木结构古建筑普遍存在倾斜歪闪等损伤问题,严重影响了古木建筑的安全,亟需纠偏修复。研究尝试提出一种整体纠偏方法,构建木构架结构纠偏理论计算模型,通过数值模拟方法分析了纠偏过程的可行性,并以某多层木结构建筑的纠偏复位过程为例加以验证。结果表明:纠偏后结构楼层偏移明显减小,纠偏过程中主要结构构件仍然处于弹性范围内,纠偏效果良好,可为同类古建木构架纠偏理论研究提供借鉴。

木材老化对古建筑木梁抗弯性能的影响分析

为研究木材老化对古建筑木梁抗弯性能的影响,分析了木材的老化机理,采用等效截面法并结合国内木梁老化深度经验公式,提出了老化木梁抗弯承载力退化模型,并对某古建筑的木梁进行了承载力退化评估。对未老化与老化木梁进行了单调加载数值模拟,并通过试验验证了模型的合理性;在此基础上,进一步分析了老化均匀度与老化深度对木梁抗弯性能的影响。结合《木结构设计标准》(GB 50005—2017)中受弯构件的承载力计算公式,提出了考虑老化影响的木梁抗弯承载力折减系数计算公式。结果表明:老化对木梁抗弯承载力的影响与老化均匀度呈线性相关,与老化深度呈一元二次多项式关系。老化深度越深且老化均匀度越大,木梁承载力越低。

木结构斗拱出挑层数对建筑抗震性能的影响

木结构古建筑是世界建筑史的重要组成部分,目前的研究大部分集中在结构整体的抗震性能上,或者单独对构件的受力机理进行分析,主要的研究构件包括斗拱、柱、梁架等,但是在构件对整个结构抗震性能的影响方面研究较少。以殿堂型结构中的斗拱为研究目标,利用ANSYS和ABAQUS软件对其展开模态与动力时程分析。通过对不同层数的斗拱进行分析比对,总结出斗拱层数变化对其抗震性能的影响。结果显示,在地震波作用下两模型柱脚和柱顶位移相差不大,但屋脊位置的位移量五踩斗拱模型比三踩斗拱模型多40%,五踩斗拱的柱顶加速度比三踩斗拱的柱顶加速度小23.02%,五踩斗拱的屋脊加速度比三踩斗拱屋脊小24.27%,证明在一定范围内斗拱层数的增加有利于结构的耗能减震。

木构架古建筑基本周期的分析方法

针对现行规范近似公式存在的不足,结合单层、两层砖围护墙木构架古建筑的构造特征,构建了设有集中质量和连续分布质量的悬臂杆分析模型,以考虑屋顶、楼盖的质量和位置,以及围护墙、木构架的质量和刚度分布规律。依据结构动力学原理,采用等效质量法将分析模型等效为单质点悬臂杆模型,推导了中部集中质量和连续分布质量的等效公式,以及基本自振周期的计算公式。所研制的分析模型较好地反映了古建筑的大屋顶、楼盖及围护墙对结构自振周期的影响,相应的计算公式可以得出结构的横向和纵向基本周期。结合3座典型古建筑的动力特性试验研究,介绍了计算公式的运用方法,并将基本周期的计算值与实测值进行了对比,表明提供的分析方法适用于围护墙在横向、纵向不同布置的木构架古建筑的基本周期分析。

古建筑落叶松木构件自然老化材性变化

为探究古建筑木构件自然老化材性变化,以距今约350 a的一段古建筑华北落叶松木构件及与其具有相似年轮宽度的落叶松新材为研究对象,加工标准力学试件,测定试件的材性参数(颜色、全干密度、力学性能参数)及无损检测参数(微钻阻力值、超声波波速),对比分析自然老化木材试件的无损检测参数与材性参数的变化及分布规律,并基于所测得的新旧材两类试件的材性及无损检测参数建立落叶松木材物理力学性能参数的多元回归模型;研究结果表明:所测老化木材试件物理力学参数及无损检测参数均衰减明显,且颜色具有极显著差别;自然老化木材试件各参数变异系数均高于新材试件,但两者均符合正态分布,建立的落叶松木构件物理力学性能参数的评估模型具有较高评估性能。

地铁盾构下穿古建筑振动监测与保护研究

为确保地铁盾构下穿古建筑物施工安全,确定先评估、先加固、施工监测、后评估、后加固总体技术路线。通过建立古建筑1︰3.52的实体模型并进行振动台试验获取结构阻尼比,利用Ansys进行三维建模,采用结构与模态分析,针对易损结构进行加固预防,为后续振动监测与盾构施工提供参考依据,结合试验区施工监测数据,调整施工参数。结果表明:在静力分析下该结构位移最大值约为14.01 mm,验证了三维模型的有效性。通过模态分析确定结构模型基本频率为0.59046 Hz,最易受损位置为斗枋处。在盾构穿越过程中,古建筑物加速度变化幅度小于0.003 m/s2,振动频带主要集中在0.6~20.5 Hz,振动频带处于正常范围,对古建筑物基本无影响。针对盾构下穿古建筑物提出以“地铁盾构穿越以匀速掘进为主,避免运营高峰期作业,影响区地层之间使用注浆加固,对古建筑物易损结构进行支护,施工时采取隔振减振方案”的总体解决思路,为后续类似工程建设提供参考。

古建筑保护中色彩采集方法及流程设计的应用研究——以岳麓书院为例

建筑色彩数据库的建立,是古建筑保护工作深化的重要技术节点,其技术流程可包括色彩体系的选择、取色仪器的匹配及色彩样本的误差处理。当前古建筑保护存在着色彩原真意识淡薄、数据资料缺乏以及采集规范不全等问题,古建筑色彩保护严谨性与科学性亟待提高。通过梳理色彩数据采集流程以及方法,初步建立了一个系统、明确、可执行的工作模式,为古建筑色彩采集工作提供参考;并规范色彩数据采集工作的流程设计以及数据定量纠偏方法,为古建筑色彩定量研究提供支持。实践结合岳麓书院古建筑群色谱研究,致力于解决建筑古迹色彩采集所涉及的样本选择、高度障碍、材质不均、光强条件、湿度差异、色温影响等重难点问题,为岳麓书院古建筑群后续色彩研究奠定数据基础,是古建筑色彩保护中色彩采集技术路线的有效支撑。