藏青杨旧材无疵试样力学性质试验研究

藏青杨是藏式古建筑木结构的常用材料,但目前对该种材料的力学性质研究不足,尤其是藏式古建筑中的藏青杨旧材。为此,通过对锯解自一根典型藏式古建木结构旧梁的无疵试样进行力学测试,得到了藏青杨旧材的力学性质参数。研究表明：高宽比为1∶3试样的径向、弦向局部抗压强度较全截面抗压强度分别提升33.8%和64.2%;对于文中使用的小尺寸受拉试样,试样的锯解方式对抗拉性质影响较大;在考虑强重比的情况下,对于大多数藏式木结构构件,落叶松是更为合适的替换用材,而若仅需要对横纹径向受压构件进行替换时,红松则更合适。此外,通过试验得到的藏青杨旧材弹性常数也可作为藏式古建筑木结构仿真建模和有限元分析的基础。     

中国古建筑木结构模型的振动台试验研究

通过一殿堂木结构 1∶3 5 2模型的模拟地震振动台试验 ,研究了结构动力特性及地震反应的变化规律。将榫卯和斗拱的力学模型比拟为变刚度弹簧单元 ,进行了动力时程分析。结果表明 ,由于大震下柱底与础石的滑移和榫卯与斗拱的摩擦阻尼作用 ,大幅度减少了上部结构的地震响应。因此 ,中国古建筑木结构具有良好的耗能与减震性能 ,它所蕴涵的受力机理 ,对现代建筑也有一定的借鉴作用。     

唐五代建筑材等与平面主要尺度特征关联性研究

本文搜集宋《营造法式》之前唐五代木构建筑遗存中的典型实例,研究材等与平面各主要尺度特征的关联性。探究建筑材等与建筑当心间、步架均值、外檐出跳均值等平面主要尺度的相关性,初步推论：唐五代木构建筑中,建筑的材等等级与当心间,有成正比的趋势。材等与步架比值在8.85~16.94 的范围内,材等与外檐出跳比值在 2.03~3.75 的区域范围。为古建筑营造尺度规律的研究提供一定的参考。     

苏北金字梁架及其文化意义

广泛应用于苏北传统建筑中的金字梁架,是区别中国古建筑抬梁、穿斗、井干三大结构体系之外的一种特殊的木构体系。本文在广泛调研的基础上,分析其梁架形式、受力特点和构造做法,并进而初步探讨了金字梁架的起源,揭示其文化意义及在中国古代建筑史研究中的重要价值。     

基于环境激励的藏式古城墙动力特性研究

藏式古城墙具有很高的历史文化价值，但历经数百年风雨侵蚀后，普遍存在较严重的病害，影响其安全性能。为获取藏式古城墙的动力特性，进而为藏式古建筑性能的精准评估提供重要依据，采用环境激励法对某藏式古城墙进行现场动力测试。基于环境激励数据，利用协方差驱动的随机子空间法进行模态参数识别。通过一经典算例验证该方法识别模态参数的精度。同时结合随机减量技术及协方差随机子空间方法，得到城墙平面外振动的频率、振型与阻尼比。最后，考虑阻尼比机理复杂、识别误差较大的问题，基于卡美罗下界(Cramer-Rao lower bound)对城墙阻尼比进行进一步精确估计，从而得到变异性更小的阻尼比识别结果。以E段城墙为例，卡美罗下界法比基于随机减量技术的随机子空间法、节约时域法识别阻尼比的离散性更小，变异系数分别从0.273、0.290减小到0.046。     

Advances in structural mechanics of Chinese ancient architectures

Chinese ancient architectures are valuable heritage of ancient culture of China. Many historical building have been preserved up to now. The researches on the structural mechanics of ancient architectures show the different aspects of structure and mechanics. Systematical studies on the structural mechanics of ancient architectures have been carried out at Xi’an Jiaotong University since 1982. It is related with the need of repair of some national preservation relics in Xi’an. These studies include: 1) Ancient wooden structures including three national preservation relics Arrow Tower at North City Gate, City Tower at East City Gate, and Baogao Temple in Ningbao, Zhejiang province. 2) Ancient tall masonry building, the Big Goose Pagoda and Small Goose Pagoda in Xi’an. 3) Mechanical characteristics of ancient soil under foundation and city wall; the influence of caves in and under the ancient City Wall on the stability of the wall. 4) The typical Chinese ancient building at the center of city: the Bell Tower and Drum tower. 5) The behavior of Dou-Gong and Joggle joint of Chinese ancient wooden structure. 6) The mechanical behavior of ancient soils under complex stress state. A new systematical strength theory, the unified strength theory, is used to analyze the stability of ancient city wall in Xi’an and foundation of tall pagoda built in Tang dynasty. These researches also concern differential settlements of Arrow Tower and resistance to earthquake of these historical architecture heritages. Some other studies are also introduced. This paper gives a summary of these researches. Preservation and research are nowadays an essential requirement for the famous monuments, buildings, towers and others. Our society is more and more conscious of this necessity, which involves increasing activities of restoration, and then sometimes also of repair, mechanical strengthening and seismic retrofitting. Many historical buildings have in fact problems of structural strength and stability; the need for further studies on structural mechanics and materials is definitely growing.     

基于Gustav法的木结构古建筑群火灾风险评估

为了研究大型木结构古建筑群的火灾风险,深入西江千户苗寨、郎德上寨、大利侗寨、肇兴侗寨等大型木结构古建筑群开展实地调研,并归纳总结了大型木结构古建筑群的火灾危险性特点.结合上述火灾危险性特点,构建了基于Gustav法的大型木结构古建筑群火灾风险评估模型,并应用此模型对西江千户苗寨进行火灾风险评估:使用层次分析法确定了11...     

古建筑修复用熟石灰性能优化及机理研究

研究了矿渣、循环流化床锅炉燃烧脱硫灰(CFBC脱硫灰)和硅灰对熟石灰性能的影响及作用机理,并与理想的古建筑修复材料——强度等级为NHL2的天然水硬性石灰(简写为NHL2)进行性能对比,探讨了改性熟石灰用于古建筑修复的合理性.结果表明:由于火山灰反应及对熟石灰微观结构的影响,矿渣、CFBC脱硫灰和硅灰均可明显改善熟石灰的力学性能、防水性和耐候性;与NHL2相比,掺矿渣的熟石灰力学性能、防水性、耐候性和柔性均有所提高,掺CFBC脱硫灰的熟石灰性能优势较小,掺硅灰的熟石灰抗压强度和耐候性能较好,但防水性和柔性较差.在古建筑修复中,可利用质量分数为20%的矿渣作为熟石灰的添加剂.     

Investigation of fibre reinforced mud brick as a building material

Most of the buildings in the rural areas are made out of limestone, low quality traditional concrete brick and adobe. But these materials do not have sufficiently high compressive strengths. In the present research, an earthquake-resistant material with high compressive strength has been sought. To this end, the mechanical properties of certain combinations of fibrous waste materials and some stabilisers were investigated thoroughly and some concrete conclusions were drawn. It was concluded that the interface layers of fibrous materials increased the compressive strength and a certain geometrical shape of these layer materials gave the best results. The mix proposed satisfies the minimum compressive strength requirements of ASTM and Turkish Standards.     

云南藏区木结构民居特征分析

对云南藏区的民房及宗教建筑的类型作了介绍,并对其建筑结构形式进行了总结,同时分析了云南藏区村寨的规划特色,为古建筑学、民族学、旅游文化发展研究等方面提供了参考依据。     

Strain rate and aging effect on the mechanical properties of sheet steels

This study was primarily involved with the experimental determination of the dynamic mechanical properties of five different sheet steels. The nominal yield strengths of these five types of sheet steels ranged from 172 to 690 MPa (25–100 ksi) and the range of strain rates varied from 10⁻⁴ to 1.0 mm/mm/s. All these five materials were studied in both longitudinal and transverse directions under various strain rates, and some materials were also tested under different strain rates and different amounts of prior cold stretching. In addition, two types of steels were tested to estimate the aging effect on the mechanical properties of sheet steels. The test results showed that the proportional limit, yield strength, and ultimate tensile strength increase with increasing strain rate. In general, the amount of increase was found to be dependent on the static yield stress of sheet steel, the amounts of prior cold stretching, and the strain rates used in the tests, and independent on the test directions (longitudinal or transverse), test types (tension or compression), and material aging conditions (aged or nonaged). General equations were also derived to predict the tensile and compressive yield stresses for strain rates ranging from 10⁻⁴ to 10² mm/mm/s.     

Experimental investigations on mechanical properties and column buckling behavior of structural bamboo

Bamboo, a fast‐growing natural material with a high strength‐to‐weight ratio, provides an environmentally friendly alternative for building construction. This paper presents experimental studies on natural bamboo and glued laminated bamboo (GLB) products in order to provide fundamental knowledge for the structural design of bamboo buildings. Tensile coupon tests and compressive tests were conducted on small clear specimens, and bending tests were conducted to evaluate the bending strength and modulus of elasticity for GLB beams. It was found that tensile strength in the transverse direction was very low. Therefore, in practical applications, it is recommended that the transverse loading in GLB should be addressed very carefully. Compressive axial tests were conducted to investigate the buckling behavior of natural Julong bamboo (Dendrocalamus giganteus). A sample design procedure against buckling was proposed on the basis of the test results. The mechanical properties and buckling analysis presented in this paper may provide guidance for more structural applications of bamboo in building constructions with enhanced structural performance. Copyright © 2014 John Wiley & Sons, Ltd.     

古建筑木结构抗震构造评估研究

为保护古建筑,采用归纳及分析方法,对中国古建筑木结构的抗震构造评估进行了探讨.基于《古建筑木结构维护与加固技术规范》相关规定,对古建筑木结构抗震构造的评估内容进行了论述;基于古建筑抗震构造评估现状,对现有的评估方法进行了归纳和汇总;基于2个典型实例,对古建筑木结构抗震构造评估内容和方法提出了相关建议.结果表明:中国古建...     

Advances in structural mechanics of Chinese ancient architectures

Chinese ancient architectures are valuable heritage of ancient culture of China. Many historical building have been preserved up to now. The researches on the structural mechanics of ancient architectures show the different aspects of structure and mechanics. Systematical studies on the structural mechanics of ancient architectures have been carried out at Xi’an Jiaotong University since 1982. It is related with the need of repair of some national preservation relics in Xi’an. These studies include: 1) Ancient wooden structures including three national preservation relics Arrow Tower at North City Gate, City Tower at East City Gate, and Baogao Temple in Ningbao, Zhejiang province. 2) Ancient tall masonry building, the Big Goose Pagoda and Small Goose Pagoda in Xi’an. 3) Mechanical characteristics of ancient soil under foundation and city wall; the influence of caves in and under the ancient City Wall on the stability of the wall. 4) The typical Chinese ancient building at the center of city: the Bell Tower and Drum tower. 5) The behavior of Dou-Gong and Joggle joint of Chinese ancient wooden structure. 6) The mechanical behavior of ancient soils under complex stress state. A new systematical strength theory, the unified strength theory, is used to analyze the stability of ancient city wall in Xi’an and foundation of tall pagoda built in Tang dynasty. These researches also concern differential settlements of Arrow Tower and resistance to earthquake of these historical architecture heritages. Some other studies are also introduced. This paper gives a summary of these researches. Preservation and research are nowadays an essential requirement for the famous monuments, buildings, towers and others. Our society is more and more conscious of this necessity, which involves increasing activities of restoration, and then sometimes also of repair, mechanical strengthening and seismic retrofitting. Many historical buildings have in fact problems of structural strength and stability; the need for further studies on structural mechanics and materials is definitely growing. __________ Translated from Advances in Mechanics, 2006, 36(1): 43–64 [译自: 力学进展]     

福建土楼与福州三坊七巷夯土墙材料性能对比试验研究

福建土楼建筑群与福州三坊七巷建筑群为福建省两大特色文物古建筑群,这两个建筑群的围护墙体均采用夯土墙,但两类夯土墙的性能存在显著的差异性。本文以采用传统工艺建造的新夯土墙及历史既有的夯土墙为样本,对两种不同类型夯土墙的材料配比及材料抗压强度等性能进行了对比试验研究,研究结果表明福建土楼夯土墙的材料抗压强度显著高于福州三坊七巷夯土墙,而材料配比是影响夯土墙材料性能的最主要因素。相关研究成果可作为历史夯土墙修缮及新建夯土墙的技术参考。     

Cement composites with limestone dust and different grades of wood sawdust

This paper presents a parametric experimental study which investigates the potential use of limestone powder wastes (LPW) and wood sawdust wastes (WSW) combination for producing a lightweight composite as a building material. Some of the physical and mechanical properties of brick materials having various levels of LPW and WSW with different particle sizes are investigated. The obtained compressive strength, flexural strength, unit weight, ultrasonic pulse velocity (UPV) and water absorption values satisfy the relevant international standards. The results show the effect of high level replacement of WSW with LPW does not exhibit a sudden brittle fracture even beyond the failure loads, indicates high energy absorption capacity, reduce the unit weight dramatically and introduce a smoother surface compared to the current bricks in the market. It shows a potential to be used for walls, wooden board substitute, alternative to the concrete blocks, ceiling panels, sound barrier panels, absorption materials, etc. Recycling of unmanaged WSW and LPW as new brick material supplements appears to be viable solution not only to the environmental problem but also to the problem of the economic design of buildings.     

Influence of parent concrete on the properties of recycled aggregate concrete

This paper discusses first the properties of recycled aggregates derived from parent concrete (PC) of three strengths, each of them made with three maximum sizes of aggregates. The relative physical and mechanical properties of fresh granite aggregate are discussed. Using these nine recycled aggregates, three strengths of recycled aggregate concrete (RAC) were made and studied. Typical relationship between water–cement ratio, compressive strength, aggregate-cement ratio and cement content have been formulated for RAC and compared with those of PC. RAC requires relatively lower water–cement ratio as compared to PC to achieve a particular compressive strength. The difference in strength between PC and RAC increases with strength of concrete. The relative evaluation of tensile and flexural strengths and modulus of elasticity has also been made.     

古建筑木结构叠合梁与组合梁弯曲受力研究

采用力学分析方法,研究了古建筑木结构叠合梁与组合梁弯曲受力问题。以工程中常见的矩形木梁为例,讨论了如下3个问题:1)单梁开裂形成叠合梁后的弯曲受力性能;2)叠合梁与组合梁弯曲受力性能的区别;3)古建筑叠合梁"工字形"抗弯截面的合理性。结果表明:1)单梁开裂后形成叠合梁,将导致截面弯应力峰值大幅度增加;2)单梁加固采用组合梁做法比叠合梁做法更能节约材料且效果更好,且采用钢材加固木梁比木材加固木梁所需截面尺寸小;3)古建筑叠合梁"工字形"截面与相应等高度矩形截面相比,受弯承载力变化不大,具有合理性。     

阿坝县藏族民居建造体系的当代自发演化及研究价值——以哇尔玛乡铁穷村藏族住宅为例

通过对地处川西北草地藏区的阿坝县铁穷村藏族乡土住宅的实地调研,文章梳理了其建造体系在结构、材料及构造体系等方面的主要特点,并分析了各构造作法由传统到当代的变化;最后初步总结了以上、中阿坝地区夯土木构住宅为代表的川西北草地藏区乡土民居建造体系自发演化现象的特点和研究价值。     

再生混凝土的长期力学性能试验研究

为了保证再生混凝土结构的工程质量和安全性,需要对再生混凝土的长期力学性能作出准确评价。基于这一工程需要,系统对不同强度等级的再生混凝土的抗压强度、劈裂抗拉强度和抗折强度以及弹性模量随时间的发展规律进行研究。结合试验结果对再生混凝土上述各长期力学性能的变化规律给予分析,并对普通混凝土长期力学性能计算方法对再生混凝土的适用性进行考察。试验结果表明:再生混凝土的长期抗压强度与普通混凝土存在一定的差异,主要表现为强度和弹性模量随龄期增长较多,发展相对较快。普通混凝土长期力学性能计算公式不适用于再生混凝土。基于试验结果,提出再生混凝土长期力学性能计算方法。