Beschichtungen auf direkt befahrenen Tiefgaragenbodenflächen von Weißen Wannen. Physikalische Beanspruchungen – Planungsgrundlagen – alternative Beschichtungsvarianten

Coatings on directly vehicle‐carrying floor slabs of watertight concrete constructions in underground carparks physical stresses – design codes – alternative coating systems According to DIN 1045‐1 directly vehicle‐carrying park decks have to be realized with additional measures (crack‐bridging coating systems). At least surface protection system 11 (SPS 11) according to the Guidelines for the Protection and Repair of Concrete Components of the German Committee on Reinforced Concrete (DAfStb) are among others a possibility to meet this requirement. On the market available crack‐bridging coating systems with a general technical approval are not usefull on concrete surfaces with high water contents (water saturation values of 90 %) as they may occur in floor slabs of watertight concrete constructions. Experiences with practical damage cases show, that with approved SPS 11‐systems osmotic induced bubbles may occur preferably on backside saturated floor slabs of watertight concrete constructions. In consequence the physical stresses of a coating (osmotic processes, capillarity reactions, hydraulic pressures as well as gas pressures) will be quantitatively estimated and compared with the capability of market systems. Alternative coating systems are presented and practical recommendations in order to avoid damages are given.     

Größere Spannweiten durch Flachdecken aus Konstruktions‐Leichtbeton

Wide spans due to Flat Slabs with Structural lightweight aggregate Concrete Structural lightweight aggregate concrete (SLWAC) shows a much more favourable ration of dead weight to strength than normal weight concrete. The present report indicates the possibilities resulting out of this for the optimisation of flat slabs in view of wider spans. Considering the specific material properties of SLWAC and their consequences on the load bearing system of flat slabs the solution of a hollow body slab is developed in which SLWAC and normal weight concrete are used combined. Those slab systems reach clearly wider spans than conventional nonprestressed normal weight concrete slabs.     

Tragfähigkeit von Spannbeton‐Fertigdecken aus Plattenbauten der DDR und deren mögliche Wiederverwendung als Massivdach

Ultimate Loading Capacity of Former GDR's Precast Pre‐Stressed Concrete Slabs and Possible Reuse as Solid Roof Due to the city rebuilding of eastern Germany a large number of buildings made with precast concrete slabs, produced in the former GDR will be deconstruct. The removed slabs and concrete elements should be re‐used as a result of economical and environmental considerations. What happens to the concrete components under changed boundaries and geometry parameters is discussed within this paper. Especially the missing of any transverse reinforcement near the supports has been tested.     

Vorschlag für die Bemessung der Deckenknoten mit Stützen aus hochfestem Beton

Design Approach for effective Strength of Column-Slab Joints between Columns of High-Strength Concrete At present the German concrete construction standard contains no approach for the prediction of the load transfer mechanism from columns of high strength concrete (HPC) through floor slabs of normal strength concrete (NSC). In this paper a design approach due to test results with high slab loads is presented. Because of the small amount of the conducted tests in this and in other published programs, the proposed equation appears to be on the safe side, compared with the design approach in the ACI code, that is based on experiments with unloaded slabs.     

Bemessung von Fundamentplatten aus Stahlfaserbeton gemäß ÖVBB Richtlinie Faserbeton und DBV Merkblatt Stahlfaserbeton

Static Analysis and Verification of Steel Fibre Reinforced Concrete Foundation Slabs according to the Austrian Guideline “Fibre reinforced concrete” and DBV (German Concrete Association) Recommendations “Steel fibre reinforced concrete” Steel fibre reinforced concrete is used for foundation slabs of housing structures since many years. The Austrian guideline [1] and the DBV recommendations [2] provide material properties and design values for calculation and verification of steel fibre reinforced concrete structural members. This paper provides a comparative study on foundation slabs taking both guidelines into account. A nonlinear finite element parameter study has been performed in order to verify a simplified static calculation and verification method. This calculation method is based on the yield line theory. This paper concludes with a sample calculation for steel fibre reinforced foundation slabs according to the Austrian and German design recommendations.     

Stützen‐Deckenknoten für Schleuderbetonstützen

Column‐Slab Joints for Spun Concrete Columns In this paper joints consisting of high capacity spun concrete columns with reinforcement ratios up to 14,7% and slabs made of normal strength concrete are discussed. The main focus was put on the load transfer from the columns through the concrete slab. In all tests the reinforcement of the columns in the joints was not continuous. For spun concrete columns an optimized solution using a high strength core is presented. The conventional joints and the joints using a high strength core are compared in experimental tests. The results showed that the new joint design is capable of transferring higher loads and reduce the deformations in the slab. On the basis of the experimental data a model was developed, which provides simple design equations for such joints.     

Fundamentplatten aus Stahlbeton und Stahlfaserbeton. Experimentelle Untersuchungen zur Gebrauchstauglichkeit und Tragfähigkeit

Reinforced Concrete and Steel Fibre Reinforced Concrete Rafts Experimental tests on serviceability and ultimate loading performance Houses and residential buildings are increasingly built on rafts instead of strip foundations. The main advantages of rafts are more efficient excavation works and easy concreting of the rafts itself. The use of steel fibre reinforced concrete slabs offers economic advantages if there are no special requirements on service ability such as water tightness or crack limitations. At Aachen University of Applied Sciences a comparative experimental study on the load carrying behaviour of rafts made of concrete, reinforced concrete and steel fibre reinforced concrete was carried out. The tests have proven steel fibre concrete as suitable material for rafts in case of sufficient stiffness of the subbase. In case of special requirements on service ability, reinforced concrete or combined fibre and bar reinforced concrete should be used. In that case stresses should be calculated based on the elastic theory.     

Betonverbinder für eine Hochgeschwindigkeits‐Bahnstrecke

Concrete Connectors for High Speed Rail Track The high speed line from Amsterdam to Brussels is currently one of the largest rail infrastructure projects in Europe. For 65 kilometres it uses the RHEDA 2000® slab track system with flat concrete slabs as sub‐ and superstructure in order to optimize concrete consumption. The slabs have to be connected by fastening elements. This report describes the development of specific elements to meet exactly the requirements of the project. Comprehensive testing had to prove that all specifications concerning load bearing capacity, displacements at serviceability load level and fatigue resistance are fulfilled. The fatigue strength was evaluated by developping a Woehler curve experimentally.     

砖混结构房屋宜用现浇楼板和复合保温墙体

论述了在民用住宅砖混结构中,应以现浇混凝土楼（屋）面板替代预制空心板。同时提出 现浇板可做外悬,为做复合保温墙体创造有利条件。     

Beton erhöhter Brandbeständigkeit mit Polypropylenfasern: Nachweise im Frisch‐ und Festbeton

Increased Heat‐Resistant Concrete with Polypropylene Fibres: Testing Methods in set and unset Concrete The consequences of fires in tunnels in Austria and other countries resulted in seeking for more information on the effects of fires in tunnels on the concrete structure. The findings from different research programs led to a new guideline of the Austrian Society for Concrete, and Construction Technology (ÖVBB). By adding polypropylene fibres a spalling of concrete of the inner lining can be avoided successfully in tunnels even under the extreme condition of fires. An equal distribution of fibres in the concrete is essential for their effectiveness. To verify the distribution of fibres during construction, testing methods which are explained in the article at hand were developed. In addition, the conclusions derived from the practical use at a construction site are shown.     

Bemessungsregeln und Ausführungshinweise für Schubkerven im Holz‐Beton‐Verbundbau

In der vorliegenden Arbeit werden theoretische und experimentelle Untersuchungen zur Beschreibung des lokalen und globalen Tragverhaltens von Holz‐Beton‐Verbunddecken, die an der Universität Innsbruck durchgeführt werden, zusammengefasst. Dabei werden auf der Basis eines Versuchsprogrammes Rechenformate zur lokalen Bemessung der einzelnen Verbindungen sowie der gesamten Verbundträger abgeleitet. Design Rules and Details for Construction of Grooves in Timber‐Concrete‐Composite Constructions This article presents a scientific work on timber concrete floor systems with grooves. Experimental and theoretical works done at university Innsbruck are presented in order to describe the local and global behavior of these shear‐connectors. As a result, all relevant parameters as well as design rules are identified.     

Kaiser‐Wilhelm‐Gedächtniskirche Berlin – Qualität und Geschichte einer Instandsetzung

The “Kaiser Wilhelm Gedächtnis” church in Berlin – quality and history of a restoration. Concrete and reinforced conrete are young building materials with an increasing importance. The “Kaiser Wilhelm Gedächtnis” church in Berlin was built nearly 50 years ago as a steel and reinforced concrete construction. This object is an example for the restoration of an important monument following the current guidelines.     

钢筋混凝土叠合板组合模具研究现状及分析

目前,我国装配式建筑中叠合板是使用频率最高的预制构件,叠合板模具的设计、制作直接影响工程造价及工期。研究目前市场上各企业叠合板模具现状,叠合板模具类型可分为分离式组合模具、拼装式组合模具、调节式组合模具,列举各类型模具设计实例,分析该种类型的优缺点。     

水泥混凝土桥双层SMA桥面铺装关键施工工艺

为提高水泥混凝土桥双层SMA桥面铺装的施工质量,从桥面板的处理、桥面板不平度以及双层SMA铺装的碾压工艺研究等几个方面,对水泥混凝土桥双层SMA桥面铺装的关键施工工艺进行了研究,并提出了针对性的改进措施,从而提高桥面铺装质量。     

大开间住宅混凝土楼板裂缝问题及改进建议

分析了我国传统预制装配式混凝土楼板及当前现浇混凝土楼板中常见裂缝的类型、产生原因及防治措施。指出施加预应力预制年是避免裂缝出现的有效方法。建议采用高效预应力装配整体式楼板及预应力双向叠合式楼板,以解决大开间住宅混凝土楼板的裂缝问题。     

预制带肋底板混凝土叠合板的技术特点及经济比较

对各类楼板进行了总结,分析了预制带肋底板混凝土叠合板的技术特点。分别采用预制带肋底板混凝土叠合板、现浇钢筋混凝土楼板和压型钢板组合楼板,设计了四边简支和四边固支的4.2m×6m的楼板,计算了工程量,然后按全国统一建筑工程基础定额分析造价。结果表明,预制带肋底板混凝土叠合板不但具有方便施工、节约模板和支撑、省工省时省料等突出优点,而且还具有明显的经济优势,适合在房屋建筑中大力推广应用。     

Schallabsorbierende Doppelböden

Sound‐absorbing raised floors. Concrete core cooling is increasingly used as a temperature control method for office buildings. Concrete core cooling systems are integrated in slabs and preclude the installation of sound‐absorbing suspended ceilings, which would reduce the performance of such systems to uneconomical levels. Sound‐absorbing raised floors offer an alternative to sound‐absorbing ceilings. More than 60 sound absorption coefficient measurements were carried out in a reverberation chamber for different fitted carpets, sound‐absorbing raised floors and combinations thereof. This paper describes the different floor configurations and the corresponding sound absorption coefficients.     

大掺量粉煤灰混凝土在大体积混凝土中的应用

临沂经济开发区投资创业服务中心投资创业服务中心综合楼工程地下室底板大体积混凝土施工,地下室底板厚度为1.700 m,混凝土用量近1.6万m3,施工中混凝土采用预拌混凝土,混凝土的配合比、混凝土的运输、施工部署、施工工艺、养护测温等方面采取了综合措施,有效地防止了大体积混凝土产生危害裂纹.     

Zur Ermittlung der Beton‐ und Stahlspannungen

On the Determination of Concrete and Steel Stresses The limitation of concrete and steel stresses is required in DIN 1045‐1 [1] as well as in EC 2 [2]. A general procedure of their determination is reported for reinforced concrete sections subjected to bending and longitudinal force. Finally tables for usual practical cases are presented.     

Alpenquerende Tunnel: Materialbewirtschaftung und Betontechnologie beim Lötschberg‐Basistunnel

Materials Management and Concrete Technology on the Lötschberg Base Tunnel During construction of the 34.6 km long Lötschberg base tunnel some 16 million tonnes of material was excavated; 10 million tonnes in the south section and 6 million tonnes in the north section. A comprehensive global concept was developed for materials management. Central to this concept was the processing of excavated material into concrete aggregate used for constructing the concrete structures of the project. Of particular interest is the fact that it was possible to produce AAR stable concrete from aggregate which was partially alkali aggregate reactive.