关于框架结构平面开孔后伸缩缝设置问题的探讨

多层框架结构结构平面开孔后伸缩缝的合理设置可以减少在设置永久温度缝后结构扭转效应,并且更加合理的满足建筑的使用功能。结合工程实践,对钢筋混凝土框架结构伸缩缝设置的若干问题进行了研究,取得了良好的效果,可供同类工程借鉴。     

补偿收缩混凝土技术在大跨度框架结构施工中的应用

该工程为大跨度钢筋混凝土框架结构,面积大,通过设置膨胀带和后浇带,利用JEA补偿收缩混凝土等措施,确保超长混凝土框架结构不设置伸缩缝,满足了工艺要求。     

混凝土柱上轻钢屋盖单层房屋结构沿纵向伸缩缝设置方法的探讨

混凝土柱上轻钢屋盖单层房屋结构屋盖为轻钢结构,屋盖以下沿纵向一般为钢筋混凝土框架结构,两者对温度变化引起的胀缩变形的适应能力不同,如何合理设置伸缩缝成为该类结构设计的难点之一。本文结合工程实践经验对该类结构的节点的伸缩缝设置方法进行探讨。     

超长框架结构内置伸缩缝抗裂研究

在建的百万千瓦机组大型火力发电厂主厂房由于工艺上原因,通常无法设置伸缩缝而形成超长结构。采用钢筋混凝土框架的超长结构具有良好的技术经济指标,但解决由于超长带来的过大的温度(收缩)效应是一个非常重要的课题。本文基于某火力发电厂钢筋混凝土框架结构的基本数据,建立了超长框架结构在温度(收缩)作用下的裂缝宽度分析模型,研究了内置伸缩缝对降低超长框架温度(收缩)效应的影响及其有效性。     

不同构造措施对超长钢筋混凝土框架厂房温度应力分布的影响

对于超长钢筋混凝土框架结构,变温的作用常常导致混凝土梁和楼板的开裂.采用SAP2000有限元软件对某一超长钢筋混凝土框架结构厂房在降温作用下的结构温度应力进行了计算分析,并得到其分布规律.为了减小超长混凝土框架结构的温度效应,在结构中设置剪力墙、膨胀带、伸缩缝三种不同构造措施,通过有限元计算发现采用膨胀带和伸缩缝能够明显减小楼面混凝土的主拉应力和框架柱的侧移,结构中设置剪力墙虽然可以减小框架柱的侧移,但楼板混凝土的主拉应力急剧上升造成混凝土的开裂.最后,基于有限元分析的结果,提出在设计和施工阶段超长钢筋混凝土结构温度裂缝控制的具体措施.     

多层框架结构的裂缝控制分析

钢筋混凝土框架结构针对温度和收缩应力产生的裂缝 ,历来有“抗”与“放”两种不同方法 ,我国有关规范采取了简便易行的留伸缩缝方法 ,释放温度应力 .具体分析了温度和收缩应力产生的机理 ,在此基础上提出框架结构的裂缝控制设计的一些具体措施 :局部屋面或楼面设置伸缩缝 ,梁柱按温度应力计算配筋的对策控制裂缝 ,采取设置混凝土后浇带 ,使用微膨胀混凝土 ,控制水泥用量和加强养护等措施防止产生收缩裂缝 ,效果不错 .     

框架结构伸缩缝柱偏位成因及防治措施

分析了钢筋混凝土框架结构伸缩缝柱在混凝土浇筑过程中产生偏位的原因,从设计方面、施工方法以及质量管理方面提出了伸缩缝柱钢筋混凝土偏位防治措施及处理方案,供工程技术人员参考。     

超长现浇框架楼面补偿混凝土施工

1.工程概况 某综合车间工程为2层现浇框架结构,总建筑面积22380m2.车间南北长110m,东西宽93m.根据现行《混凝土结构设计规范》,本工程每间隔45m应设置一条伸缩缝,整个工程结构需留置纵向伸缩缝2道,横向伸缩缝2道.     

广州新客站结构总体设计

广州新客站铁路枢纽采用站桥合一的结构体系,总平面尺寸525m×586m,建筑面积56万m2,地下1层,地上3层。首层为地面停车场,属于室外广场;层2为铁路站台层,采用线性结构为主的预应力钢筋混凝土结构,中部采用跨度64m的拱形结构,平行轨道方向共设置9道伸缩缝;层3候车室为钢筋混凝土框架结构,其柱子部分落在桥梁上,部分落在桥墩上,平行轨道方向共设置2道伸缩缝。屋盖采用新型大跨度预应力空间钢结构,主站房屋顶为476m×222m,在屋面与两侧的无站台雨棚设置了伸缩缝。各层结构体系、刚度、质量等相差较大,介绍了各层结构特点、相互关系及其结构布置等。     

简述结构设计中常见的几个问题

结构设计中相当部分构件的设置,规范仅给出了最低限值或建议取值,实际设计过程中各人的理解不同可能对整个设计带来相当大的区别。还有部分是属于概念设计的范畴,尤其值得我们一起探讨。1关于超长结构混凝土结构设计规范第9.1.1条中规定钢筋混凝土框架结构伸缩缝最大间距为55m,     

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.     

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.     

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).     

CONTROL OF CONSTRUCTION ACTIVITIES: III. FUZZY-BASED CONTROLLER

In this paper, a real-time fuzzy-based controller of construction activities is proposed. Because of the numerous uncertainties associated with construction activities, their control requires a different approach than the traditional feedback methods. These methods are essentially based on the knowledge of a transfer function that models the input/output relationships for the controlled system. For a highly complex and uncertain system such as a construction activity, a fuzzy-based control strategy was found to be a suitable and effective approach. The proposed control system is built in two main levels, the process and the activity levels. Each level comprises two main units, namely, the fuzzy controller and the self learning algorithm. The implementation of the control actions can be performed by either manipulating the states of the variables for the purpose of improving the process output, or changing the process behavior function for the same purpose. Practical examples are presented wherever possible to illustrate the proposed control strategy.     

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.     

城市物质空间结构中的面元素

基于建筑师立场,对大尺度的城市物质空间的诠释和操作提出分类。主要提出镶嵌状的面．元素层叠形成的面．地块-街区-街道形成的面三种面元素。面元素与点元素和线元素的主要区别在于．城市中的面自身占据较大尺度的空间面积,而点和线元素则是局部的空间构成要素。结合具体案例深入解析三种面的诠释视角对设计操作的影响。在结论中点明了提出“点-线-面”诠释和操作城市物质空间的意义。