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.     

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.     

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.     

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.     

基于点云的钢筋数量和间距自动检查算法

为改进钢筋骨架质量自动检查方法,提出了基于点云的钢筋骨架中钢筋数量和钢筋间距的自动检查算法。该算法在获取钢筋骨架实际点云和设计点云的基础上,首先对这两片点云分别进行降采样,以得到空间密集程度相同的钢筋骨架实际点云和设计点云; 其次,对降采样后的钢筋骨架实际点云和设计点云使用基于主成分分析(PCA)的方法进行粗配准。由于粗配准后的钢筋骨架实际点云和设计点云的配准精度较低,无法直接用于钢筋数量和钢筋间距的检查,对粗配准后的钢筋骨架实际点云和设计点云进行精配准。最后,基于精配准得到的钢筋骨架实际点云和设计点云,依次对钢筋骨架中的钢筋数量和钢筋间距进行检查。结果表明:精配准后的钢筋骨架实际点云和设计点云的配准精度较高,可以用于钢筋数量和钢筋间距的检查; 该算法对钢筋数量检查的准确率为100%,对钢筋间距检查的准确率为80%; 应用该算法可以有效提高复杂钢筋骨架中钢筋数量和钢筋间距检查的效率,降低人工成本。     

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).     

机制砂在隧道耐久性混凝土运用中的质量控制

从母岩的选料、级配控制、石粉和泥土含量控制三个方面阐述了控制机制砂质量的重要性，并提出了可将隧道混凝土机制砂的石粉含量限值放宽到10％的建议，以促进耐久性混凝土的研究。     

浅谈维修工程中外墙渗漏的防治与处理

结合具体工程实例,分析了建筑物外墙渗水的原因,从设计和施工两方面提出了预防建筑物外墙渗漏的措施,提出了三种处理建筑物外墙渗漏的方法,从而减少建筑物外墙渗漏的发生,更好地发挥建筑物的使用功能。     

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。     

堆土加卸载与基坑开挖叠加对既有隧道变形的影响研究

针对堆土加卸载与基坑开挖叠加效应导致既有地铁隧道变形较大的问题,建立考虑加卸载叠加效应影响的三维空间分析模型,研究不同堆土加卸载叠加基坑开挖卸载模式对邻近地铁隧道变形规律的影响,探讨隧道在堆土加载、移土卸载再叠加基坑开挖下的变形规律。结果表明:正上方堆土加卸载对隧道的竖向位移影响较大,是侧向堆土加卸载的3倍～5倍; 在经历堆土加卸载后,隧道会残留不可忽视的变形,其残留竖向位移约为加载后位移的62%; 堆土加卸载叠加侧方基坑开挖时,隧道变形受基坑开挖深度的影响较大,大于隧道埋深的开挖阶段会加剧隧道变形; 4种叠加模式中,正上方堆土加卸载-侧方基坑开挖卸载隧道最终竖向位移最大,约17 mm,侧方堆土加卸载-异侧基坑开挖卸载隧道最终水平位移最大,约8 mm,邻近隧道施工时应充分考虑叠加效应的影响,尽量避免这两种情况。