几种金属面夹芯板的耐火性能测试

用垂直构件耐火试验炉研究不同厚度的金属面岩棉夹芯板、EPS夹芯板、聚氨酯夹芯板、酚醛夹芯板的耐火性能.用岩棉与EPS、岩棉与聚氨酯进行组合进行耐火性能测试,100 mm厚的岩棉—EPS夹芯板、岩棉—聚氨酯的耐火极限分别达到85、90 min,较大提高了EPS夹芯板和聚氨酯夹芯板的耐火性能.     

复合材料波纹夹芯板成型工艺及其端部连接性能研究

提出了适合于端部连接的复合材料波纹夹芯板一体成型工艺;利用提出的复合材料波纹夹芯板成型工艺制作了一系列的波纹夹芯板;复合材料波纹夹芯板的端部连接方式采用螺栓连接,考察了复合材料波纹夹芯板的成型工艺的可靠性,并通过改变螺栓连接的参数,得到了不同连接参数对复合材料波纹夹芯板极限承载力和连接刚度的影响,并分析了原因和机理。     

燃烧条件下格构增强泡桐木夹芯板热传导模型

以单向格构增强泡桐木夹芯板为火灾试验的研究对象,建立了夹芯板的一维热传导模型,并用有限差分法计算了夹芯板的温度梯度;同时,通过夹芯板火灾试验进行了模型验证.结果表明:夹芯板在不同时间段内沿厚度方向存在明显的温度梯度;夹芯板在承受60min的火灾或者高温时,其受热面板与芯材均发生了不同程度的热分解,材料炭化并形成炭化层,阻止了热量传导;夹芯板中性轴以上部分的变化较小,性能稳定,具有一定承载能力.另外,通过分析受热过程中芯材与格构的温度变化,验证了芯材对格构性能的影响.     

实芯板的消防安全

介绍了夹芯板的分类和在建筑业使用的情况 ,分析了夹芯板的火灾危险性 ,提出了消除和减少夹芯板火灾危险和保证消防部门有效、安全扑救火灾的措施     

建筑用金属面夹芯板力学性能研究现状

金属面夹芯板因其良好的保温、防火、隔声等性能,作为围护结构在装配式建筑工程中得到了广泛的应用,而力学性能作为其保证安全性的基本性能在应用之初就得到了广泛的研究。随着金属面夹芯板在装配式建筑中的推广,新问题及新技术的出现使得金属面夹芯板的力学性能的研究更深入广泛。本文阐述了目前建筑用金属面夹芯板结构的分类及力学特点、金属面夹芯板力学性能的研究方法,以及金属面夹芯板在抗弯承载力、抗风荷载性能和抗冲击性能方面的研究现状。由此可知,目前对金属面夹芯板力学性能的研究已较为成熟。为了使金属面夹芯板有更广泛的应用,还需对层间不完全粘结以及在火灾、低温等特殊情况下的金属面夹芯板的力学性能做进一步的研究。     

工业夹芯板防火测试技术的最新进展

近２０年来,低造价厂房和超大型超市类建筑需求猛长,这类建筑的设计,建筑用材料以及建筑结构与以往传统的做法有根本性的不同。本文作者,一名来自瓦瑞顿消防研究中心的研究人员,着重讨论了一种常见的新型建材——工业夹芯板防火安全性能的最新发展情况。首先,解释一下什么是夹芯板,广义地说,在建筑上所使用的夹芯板可分为粘接式夹芯板和包层式夹芯板。１）粘接式夹芯板（又称为金属面隔热板、粘接板、复合板和大型隔热夹芯板等）。该种夹芯板通常是由里外两块金属面板和塞在两板之间的隔热材料压制成预制板形式,由于金属面板与芯部…     

彩钢夹芯板钢结构用房的火灾危险性及对策

通过几起彩钢夹芯板钢结构建筑物的火灾分析,阐述了彩钢夹芯板钢结构建筑物火灾特点,提出了目前彩钢夹芯板钢结构用房在消防安全方面存在的问题,并有针对性的提出了对策及建议。     

爆炸荷载作用下夹芯板的动力响应研究

为了得到夹芯板在爆炸荷载下的动力响应,采用试验、能量法和有限元分析方法对其进行研究.首先,介绍一种可用于夹芯板抗爆性能研究的试验系统装置及其试验结果;其次,将夹芯板的变形过程分为3个阶段,假定夹芯板通过芯材的压缩变形、面板的拉伸和弯曲消耗爆炸荷载作用到夹芯板上的能量,通过能量平衡方程得到夹芯板的变形量;最后,采用有限元...     

彩钢夹芯板受弯承载力模拟试验研究

介绍了彩钢夹芯板的基本材料性能，通过彩钢夹芯板受弯承载力模拟试验，描述了彩钢夹芯板在受弯破坏过程中的变形特点，分析了其抗弯承载破坏的主要控制因素。     

混凝土夹芯板受弯性能试验研究

通过混凝土夹芯板受弯全过程的试验研究,分析了夹芯板的变形、裂缝的开展及分布等特点,重点讨论了夹芯板工作过程中部分共同作用的特性。给出了开裂荷载和极限荷载的计算公式,计算结果与试验结果吻合较好。     

Magnetoelastische Spannkraftmessung in Bauwerken

Magnetoelastic Measurement of Prestressing Force in Civil Structures The knowledge of the tensile force of prestressing steel elements and its reliable and non‐destructive determination are of essential importance for the assessment of the structural health condition of prestressed concrete structures and tie‐back systems in terms of structural safety, serviceability and durability. For the evaluation of the prestressing force in steel tension members, the measurement technique presented in this contribution is using the magneto‐elastic effect (ME‐effect) of ferromagnetic materials. This effect describes the reverse‐proportional correlation between the mechanical stress and the magnetic properties of ferromagnetic materials. The cylindrical coiled sensors pushed over the tendon and the measuring device developed and practically optimized at the iBMB/MPA of the TU Braunschweig enable a fast and reliable measurement of the prestressing steel force after an initial calibration. In this contribution first the state of the art of prestress measurement techniques for steel tension members is presented. Afterwards, the ME‐measuring method with the basics and merits of magneto‐elastic prestressing force identification is shown. Further recent research results as well as several building applications will be discussed.     

Zustandsuntersuchung und Instandsetzung am Hauptdach des Hauses der Kulturen der Welt in Berlin

The main roof of the ”Haus der Kulturen der Welt“ in Berlin Which is very well‐known on account of its history and striking structural design – was to be inspected by the author to determine its condition and analysed with regard to the durability of the existing liquid synthetic sealant. The roof structure consists of a biaxial, curved area‐covering structural element with circumferential edge beams of pre‐stressed lightweight concrete. This is the result of the reconstruction between 1984 and 1987 following a partial collapse of the then Berlin Congress Hall in 1980. The very thin roof shell is also made of lightweight concrete and, like the edge beams, has a polyurethane‐based spray‐on seal that was specially developed for this purpose as protection against the ingress of moisture. The reason why this, at the time, novel type of seal was chosen was that it should take into account the fact that the roof design urgently needed some kind of protection against moisture that had to compensate the expected changes shape and crack movements of the roof with no damage. The following article reports on the nature, scope and main results of the analysis of the condition of the roof seal, edge beams and abutments. It will also describe the repair recommendations resulting from the investigations, which form the basis of the execution of work at the present point in time. Apart from presenting the technical principles and special features of the building that have to be taken into account during any repairs, the special features of the execution will also be addressed.     

Application of sonic and radar tests on the piers and walls of the Cathedral of Noto

The authors applied systematically sonic tests, radar tests and other diagnostic techniques on the remaining walls and piers of the Cathedral of Noto. The experimental survey was carried out by the Laboratory of the DIS, Politecnico of Milan (Person in Charge: Prof. Binda, Prof. Baronio) in collaboration with the designers (Ing. R. De Benedictis, Arch. S. Tringali) and the experts working on the reconstruction. The Prefettura of Siracusa founded the research. The right aisle and most of the dome of the Cathedral collapsed in 1996. The aim of the research was to verify the state of damage and the possibility of conservation of the walls and piers in view of the reconstruction of the damaged part of the Cathedral. Furthermore, the sonic tests were used to control the effect of grout injection used as a possible technique for repair of the damaged masonry (Proceedings of the Conference on Nondestructive Evaluation of Civil Structures and Materials, Boulder, Colorado; (1992) 329; Proceedings of the Sixth Conference on Structural Faults and Repair, 3 (1995) 195). In the following the results will be reported and the reliability of the tests will be discussed as it was confirmed by the use of other complementary diagnosis techniques (Proceedings of the Sixth International Conference on Structural Studies, Repairs and Maintenance of Historical Buildings, STREMAH 99, Dresden, Germany, (1999) 323).     

Alternative Methods of Procurement for Works of Water and Environmental Management

The paper considers methods of procurement for the construction of water- and sewage-treatment works other than the traditional use of the ICE 5th Edition Conditions of Contract and Bills of Quantities. This is as a consequence of the speed at which schemes are currently required within the water industry.
The paper particularly focuses on the use of target contracts, using the Institution of Chemical Engineers'Green Book form, and considers various types of target. It also discusses the form which tender documents may take, and how targets may be calculated.
Tendering procedures, including the use of two-stage tenders and negotiated targets, are considered, as are the procedures for cost monitoring and the financial management of the contract. Finally, the role of the engineer and quantity surveyor is considered.     

Ecological succession in mountain lake ecosystems of Southern Siberia after the introduction of the peled – Coregonus peled (Gmeli, 1778)

Abstract

This article summarizes a long-standing study of the process of introduction of the peled to the Southern Siberian mountain lake ecosystems. The peled has adapted to changes in food supply. Pressure of the euryphagous peled caused the substitution of larger forms of zooplankton by smaller ones. Similar changes occurred in the content of phytoplankton. Succession of zoobenthos in the littoral part of the lakes manifested itself as the decrease in the total biomass, in its part of zoobenthos (Gammarus) and as the increase in the biomass of other groups. The opposite changes were encountered in the profundal zone of zoobenthos (the decrease in the total biomass owing to the existence of larger forms of alpha-polysaprobes). The restructuring observed in various communities signifies the substantial changes in the whole process of generation and transformation of organic substance in the mountain ecosystems with the dominance of the introduced peled.     

基于分子动力学模拟技术的黏土矿物微观行为研究应用

黏土矿物是一类具有层状结构的硅酸盐矿物。土水相互作用对土体许多宏观力学响应、物质运移和传导起重要影响。现有的实验技术和手段即很难在物理上微观探测黏土从绝对干燥至含微量水分子的吸附过程,也很难实现黏土对放射性核素吸附过程的跟踪。使用分子动力学模拟对黏土矿物的水化性质及对放射性污染物吸附性能进行研究。以蛭石、高岭土及蒙脱土三种黏土矿物为研究对象,通过晶层间距、自扩散系数、径向分布函数、吸附复合物结构等模拟测试结果对蛭石的水化性能和黏土对放射性核素的吸附行为阐述。最后,对分子动力学模拟技术在岩土工程的应用发展进行了展望。     

土体干缩裂隙的形成发育过程及机理

土体干缩开裂(龟裂)是一种常见的自然现象,龟裂的产生会破坏土体的完整性,极大地弱化土体的工程性质。基于室内试验结果,发现龟裂发育过程可分为3个典型阶段,具有很强的时序特征,且新生裂隙一般垂直已有裂隙生长。根据水土相互作用原理和基本土力学理论,建立了土体龟裂概念模型,对实验室和自然界中观测到的相关龟裂现象及其机理进行了分析,得到如下主要结论:(1)土体中存在收缩变形空间是龟裂发育的前提,主要与土质条件有关;(2)龟裂是土体发生张拉破坏的表现形式,孔隙水的表面张力及干燥过程中引起的基质吸力(毛细水作用力)会在土体中形成张拉应力场,这是导致龟裂的主要力学诱因;(3)当张拉应力场的大小超过土体的抗拉强度或土颗粒间的联接强度时,裂隙便会产生,导致局部区域积聚的应变能释放,应力场重新调整。从宏观上看,基质吸力和抗拉强度是控制龟裂发育的两个关键力学指标,但从微观上看,土体材料尤其是结构的非均质性对裂隙发育过程和裂隙网络的几何形态特征均有重要影响。通常情况下,大部分裂隙都是在饱和阶段产生,且裂隙产生时对应的临界含水率有可能高于液限;土体表面上的"杂点"易导致应力集中,裂隙往往率先在"杂点"处产生;(4)受表面和裂隙面张拉应力场的共同作用,表层土体边缘会发生向上卷曲变形,产生"煎饼效应"。此外,土体在收缩过程中还存在收缩核现象。     

煤样吸水全过程纵波波速变化规律及波形特征实验研究

 为了研究含水煤体的纵波波速变化规律及波形特征,开展原煤试样吸水全过程的纵波测试实验;研究煤体纵波波速与孔隙率、含水饱和度之间的变化规律;基于FFT和HHT研究不同含水饱和度煤样波形幅频和时频特征。结果表明：煤体纵波波速同时受孔隙率和含水饱和度的影响;波速随含水饱和度的增加总体呈现非线性增加趋势,当含水饱和度达到70%左右时,波速增加速率明显提高;水自身性质及煤体内部孔隙水均匀存在形式是导致含水煤波速增加的主要原因。纵波波速随孔隙率的增加总体呈现线性降低趋势,含水饱和度越高波速受孔隙率影响越小,表明水的存在降低了煤体孔隙率对波速的影响。煤样在吸水过程中的波形频率分布存在显著性差异,波形主频随含水饱和度的增加呈现向低频非线性移动的“频移”现象;含水饱和度越大、孔隙率越大,波形最大幅值越小。Hilbert三维能量谱能够反应波形的频带能量分布及随时间的变化特征;随着煤样含水饱和度的增加,波形高频成分所占比例逐渐降低,且高能量频带范围不断向低频移动,表明煤体中孔隙水不但加快了波形中所有频带能量的衰减速度,而且对高频信号的吸收损耗大于低频信号。     

土体干缩开裂过程的边界效应试验与离散元模拟

为了探究土体干缩开裂过程的边界效应问题,采用不同底面粗糙度的容器开展了多组干燥试验,发现干缩裂隙存在从顶面向下和从底面向上两种典型的发育形式。并且,裂隙发育程度与土样/容器界面接触条件密切相关,从而验证了裂隙发育过程的边界效应。通过理论分析,阐明了上边界的蒸发条件及下边界的接触条件对裂隙发育形式的控制作用。为了能更深入地理解土体干缩开裂边界效应的内在机制,在试验的基础上建立离散元模型,创新性地引入了沿深度的失水速率梯度参数,模拟土样上边界的蒸发条件变化。通过设置底面摩擦系数,模拟土样下边界的接触条件变化。将模拟结果与试验结果进行了对比分析,发现二者具有较好的吻合度。总体上,土体干缩裂隙的发育过程是顶面蒸发失水与底面摩擦两种边界条件共同作用的结果。当底面摩擦系数相对较小时,裂隙发育由蒸发失水主导,大部分裂隙由顶面向下发育。随着底面摩擦系数的增加,底面接触条件对裂隙发育过程的主导作用逐渐增强,由底面向上发育的裂隙数量所占比重也相应增加。     

Die Rolle des Prüfingenieurs im System der vorbeugenden Gefahrenabwehr

The task of the check engineer in the preventative risk management system. The historical development of building regulations is characterised by the principle of preventative risk management. The current building regulation demands, that public safety and order, especially life, health and natural conditions are not endangered by buildings. The building control is the task of the state and shall be administered by the building authorities. Usually the building control of structural stability and fire protection is delegated by the authorities to state approved check engineers. It is of main importance, that check engineers are not dependent on the investor's economic interests. Up to now this independence has been ensured, because the check engineers are appointed directly by the building authorities. Due to deregulations in recent years some federal states changed their building regulations in such a form, that the risk management was not guaranteed completely. The independence of check engineers and thus the quality of risk management was severely weakened by allowing private commissions. In additon several structures were released from the obligation of checking. These changes disagree with the safety concept of DIN 1055‐100, which is adjusted wih the European Codes. The required safety level presupposes the independent checking of the structural design. Further risks of independence and quality of building checks by the check engineers can occur due to an uncritical use of the European Services Directive. In accordance with the experiences of the check engineers current risk analyses show, that it is essential for a modern preventative risk management system to align extent and intensity of authorized controlling to the hazard potential of the particular building project. Corresponding to the proposal of the German Association of Check Engineers on the IABSE‐Symposium 2007 the controlling measures should be graduated on the basis of Eurocode EN 1990 according to three hazard classes.