建筑的计算机辅助设计研究

本文主要围绕建筑行业的计算机辅助设计进行了研究,提出了一些新的看法和论点,使建筑行业的一些软件使用和设计归纳为现实的理论表现。此外,本文还结合了一些现有的建筑设计的案例进行剖析,试图将一些典型的设计手法结合到建筑设计中去,为以后建筑行业的计算机辅助设计的开展提供很好的指导作用。     

浅谈山区灌溉渠道的规划方法

随着现在科学技术的发展，水利工程的建设更是取得了举世瞩目的成就，但是在山区灌溉渠道的规划上还是存在了一些较为突出的问题。因此，本文针对对一些丘陵地形进行介绍，对山区灌溉渠道规划原则进行概括说明，并对其中存在的一些问题进行分析总结，结合自身观点对山区灌溉的方法进行解释说明。     

浅谈文物建筑(群)保护的一些问题

本文结合已完成及正在进行的一些案例以及一些权威专家观点,整理了文物建筑保护方面的一些概念,对当下我国的文物建筑保护现状提出了一些见解。     

探讨工程造价管理失控的因素及解决方法

本文对建筑工程造价管理失控的因素进行了一些探讨,并提出了预防工程造价管理失控的一些解决办法,希望能给同行带来一些参考及借鉴。     

运用传统哲学思想于房地产项目的园林景观

就如何把中国传统哲学思想的一些精华运用于房地产开发项目居住环境的园林景观设计中进行了一些探讨,着重讨论“天人合一”的和谐、统一的哲学思想在居住环境的园林景观设计中的应用。对当前园林景观设计中的一些问题进行了分析。     

原水浮游生物调查及藻类水华的防治

我国一些大型水库相继出现藻类水华,致使一些大中城市遭遇停水,对北方几座大型水库水体的浮游生物进行了调查,并提出了一些水华的防治方法。     

混凝土桥梁裂缝的预防处理分析

对混凝土桥梁裂缝产生的原因进行了分析,对常见的一些裂缝问题提出了一些预防、处理措施。     

新材料新技术创造新时代的建筑

文章针对大鼎世纪广场设计过程中,地域和业主所提出的要求进行了思考和分析,对项目设计进行了详细的介绍,并对一些新的外墙材料的技术运用作了一些探讨。     

谈谈我对基坑支护的一些认识

本文通过对基坑工程的一些阐述,对当前主要的基坑支护结构类型及计算方法进行了简要分析,对设计上存在的一些问题提出了一些拙见。     

桩基监理中应注意的有关问题

基于桩基质量的重要性对桩基工程监理过程中的一些疑难问题进行了探讨,结合监理工作实践总结了一些经验教训,提出了一些监理过程中应注意的事项和一些问题的可行的解决办法,从而保证桩基工程质量,提高桩基监理水平.     

Reliability of composite steel bridge beams designed following AASHTO''s LFD and LRFD specifications

Composite steel beam bridges designed following AASHTO's Load Factor Design (LFD) method and the newly developed Load and Resistance Factor Design method (LRFD) are proportioned for different loading conditions. They need to satisfy these conditions at maximum design load, an overloading condition, and fatigue load. The ultimate strength of compact composite steel beams is based on the fully plastic stress distribution. The capacity of non-compact beams is based on the yield or partially-plastic moment, depending on whether the beam violates all or few of the compactness or ductility requirements. In this paper, the reliability for the ultimate flexural capacity limit state of composite steel beams is investigated. The structural reliability is measured in terms of the reliability index. The statistical data on strength are generated starting from statistics on material properties and using the Monte Carlo simulation method. Statistical data on load components are compiled from the available literature. The scope of the study covers a wide range of rolled beams, span lengths, beam spacings, and two yield strengths. The deterministic study showed that the design of composite steel beams is usually not governed by the maximum design load combination, but rather by the overloading condition. The results of the reliability study indicate non-uniformity in the safety of steel bridges that are designed by the AASHTO LFD code. This is also true for AASHTO's LRFD code since it is not calibrated for the overloading condition. The value of the reliability index is a function of the compactness classification, method of design, beam spacing, span length, and section size.     

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.     

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。     

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.     

Beanspruchung der Tunnelabdichtung durch den Herstellvorgang einer Tunnelinnenschale

Loading of the tunnel sealing system due to fresh concrete pressure This report deals with the loading of the geomembrane during the construction phase of the inner shell of a tunnel. In a systematic parameter analysis at the institute for underground construction at FH Münster the geomembrane and the geotextile were tested under different realistic conditions. Laboratory testing showed a dependence on the seal support surface of the shotcrete and on the characteristics of the geotextile. The deformations of the membranes due to fresh concrete pressure are significantly smaller than the permitted values in the technical regulations. The main results of the investigations are described below.     

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).     

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.     

Developing an optimal bidding strategy in two-envelope fee bidding

Two-envelope fee bidding is used frequently in allocating commissions to willing consultants such as architects, engineers and surveyors. Consultant fees and technical scores are normally aggregated to form a total score. The consultant obtaining the highest total score is usually awarded the commission. The consultant's objective is to get the highest total score possible because this maximizes the chance of winning. Consultants can submit to the procurer any of a number of different technical proposals which is then converted to a technical score. Only one technical score+fee combination will result in the highest total score, i.e. the optimum technical score+fee combination. This paper offers consultants an approach to better identify their optimum technical score+fee combination. In using this approach consultants need to develop a total score continuum based on (1) the consultant's original technical proposal and fee, (2) the absolute lowest fee and corresponding technical score, and (3) the absolute highest technical score and corresponding fee. The total score becomes the dependent variable and the fee the independent variable. Since the total score continuum is regressed on three points it will almost certainly be curvilinear in shape. Given that the optimum total score is at the highest point of the continuum, the optimum fee can be determined through differentiation. The corresponding technical score can then be found. After adjusting the original technical proposal to reflect the corresponding technical score, the optimum fee and adjusted technical proposal can then be submitted to the procurer.     

Distribution of structural collapses and optimum reliability for infrequent environmental loads

Structures located in a particular zone of interest may be subjected to the same environmental events or the same natural phenomena that occur infrequently. That is, the structures are subjected to the same environmental loading parameters such as the peak ground acceleration, the reference wind velocity pressure, and the total ice accumulation. Therefore, the structural collapses are dependent or correlated. The correlation may affect the probability distribution of the number of structural collapses and the optimum reliability level for upgrading the exiting structures and infrastructures. This is investigated in this paper. It is shown that the coefficient of variation of the number of structural collapses is an increasing function of the correlation coefficient. This increase can be important to the selection of optimum reliability level for retrofitting of existing structures and infrastructures when the risk aversion factor is considered. An approach by taking the correlation among structural collapses into account in selecting the optimum upgrading level of a group of existing structures is presented and illustrated by a numerical example.