Vom Hofbräuhaus zum Deutschen Museum – Münchner Bauten aus Eisenbeton 1890 bis 1914 (2)

From Hofbräuhaus to the German Museum – reinforced concrete buildings in Munich from 1890 to 1914. This year (2008) Munich celebrates its 850‐year anniversary and in appropriate publications the authors try to work out the special Munich style. Little attention will be paid to a special chapter of Munich's history – the beginning of construction with reinforced concrete about 1900. Munich can claim that city to have been first in the new building technology and important buildings in reinforced concrete were designed and erected. Unfortunately, today this extraordinary architectural and engineering development is widely forgotten.     

Das Hochhausensemble am Münchner Tor

The high‐rise buildings at the Münchner Tor in Munich. The load‐bearing structure of the two high‐rise buildings at the Münchner Tor in Munich are an important milestone in the advancement of high‐rise construction in Germany. Usually for buildings of this height, a frame construction with bracing cores made of reinforced concrete is used. The load‐bearing structure of the high‐rise buildings presented in this article, however, consist completely of a composite structure. This structure supports all vertical and – via the diagonals in terms of an end channel framing – horizontal loads. Only the thin slabs and the basement box are made of reinforced concrete. The construction principle used for the High‐Rise Ensemble in Munich has made it possible to construct a building of an hitherto unknown transparency and exceptional slimness.     

Zwei Kuppeln in München: Armeemuseum und Anatomie (1903–1905) – Die ersten Betonschalen Europas

Two domes in Munich: The Armeemuseum and the Department of Anatomy (1903–1905) – The first concrete shells in Europe. In 1903 Wayss & Freytag merged with the Heilmann & Littmann studio establishing the Eisenbeton‐Gesellschaft, a manufacturer of reinforced concrete structures operating in Munich and the surrounding area. In the following two years the company – directed by Ludwig Zöllner – realized the most innovative works of the time: the Isarbrücke near Grünwald and the domes of the Armeemuseum and the Department of Anatomy of the University of Munich. This paper focuses on these two shell structures calculated by the young engineer Emil Mörsch. The innovative realizations – 7 cm thick and with a span of 16 and 22 m – were built at the same time as the Law Court (1891) and the Ministry of Transport (1904) and presented a high level of engineering that marked the final transition from 19th century steel constructions to 20th century reinforced concrete ribbed domes. The Armeemuseum was formally reminiscent of a historicist language, while the Department of Anatomy – designed by Max Littmann and built in exposed reinforced concrete – resulted in an organic unity of form, construction and material, the first such example in Munich and perhaps in Germany.     

Die “Highlight Munich Business Towers” in München – Tragwerksplanung und statische Nachweise

The Highlight Munich Business Towers in Munich. The Highlight Munich Business Towers are located in the northeast of Munich, where highway A 9 from Nuremberg is connected to the middle ring road, just a few miles from Munich’s Olympia Center. The buildings are part of the ‘Industrial Park Munich‐Schwabing’, which thus becomes even more attractive, not least because the buildings will have an ideal connection to the city centre by a new subway station. The project goes back to an architectural competition in the year 2000. The planning team of architects Murphy/Jahn, structural engineers Werner Sobek Ingenieure und climate engineers Transsolar was victorious against strong international competitors and managed the project until its completion. The building project is a special landmark in the history of highrise structures in Germany because it does completely without the concrete cores that are commonly used to stiffen a building. The resulting transparency is unique. The idea of transparency and dematerialisation lying behind the design was consequently applied to all parts of the structure and to all components, like elevators and bridges connecting the two buildings. Especially these totally glazed bridges at a height of up to 240 feet will certainly make a lasting impression on visitors.     

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.     

Untersuchungen zum Einfluss der Berechnungsmethode auf die Größe von Zwangschnittgrößen in Stahlbeton‐Tragwerken

Es wird anhand eines Rechenbeispieles gezeigt, dass die Größe von Zwangbeanspruchungen in Stahlbeton‐ und Spannbetontragwerken wesentlich von der zur Schnittkraftermittlung gewählten Berechnungsmethode abhängig ist und dass in Sonderfällen – z. B. zur Tragfähigkeitsbeurteilung älterer Bauwerke – eine nichtlineare Berechnung zur realistischen Erfassung von Zwangbeanspruchungen sinnvoll sein kann. Investigations on the Influence of Calculation Methods on the Dimension of Constraint Stresses in Reinforced Concrete Structures A calculation example shows, that the dimension of constraint stresses in reinforced concrete structures depends siginificantly on the calculation method used for the evaluation of stress‐resultants. In particular cases – e.g. assessment of the load‐bearingcapacity of older buildings – a nonlinear calculation is reasonable to have a realistic assessment of the contraint stresses.     

A new approach on the strengthening of primary school buildings in Turkey: An application of external shear wall

Considerable life and property losses have occurred because of the devastation due to the earthquakes happened in Turkey during the last 10 years. Especially, the damages that occurred on the public buildings were more serious and irrevocable when compared with the damages that took place on private buildings. In Turkey, primary school buildings constitute a large portion of the public buildings. Unfortunately, these buildings faced with heavy damages during the last earthquakes. The strengthening of existing primary school buildings in accordance with new contract specifications, thereby reducing losses of life and property to a minimum in case of an earthquake, has become one of the important issues on the agenda of the Turkish government. However, the strengthening of the primary school buildings by using the available methods is so difficult, because the strengthening works take a long time, the user of these buildings are obliged to evacuate the buildings and also there occurs extra costs caused by the additional repairs and renovations within the buildings when these methods are used. In this study, a new strengthening type of reinforced concrete buildings namely “external reinforced concrete shear wall” application method is discussed. For this purpose, three typical projects, which have been built commonly, are mentioned. The structural deficiencies observed in these buildings are given. In the experimental stage of this study, an experimental programme is formed in order to evaluate the performance of the external shear wall application. In the experimental schedule, four reinforced concrete test specimens are produced by using the design and detailing data of the considered school buildings. According to these tests, the strengthening and system improvement performed through adding external reinforced concrete shear wall to the reinforced concrete buildings will add improved behaviour, strength and rigidity to the system with its low cost besides the ease of construction and application. Since these buildings are detached and located in a multi-purpose garden, constructed as typical projects and have special architectural layout, developing this method for the existing primary school buildings will be able to be implemented in most of the primary school buildings without any problems.     

Dreiaxiale Stoffgesetze für Beton – Grundlagen,Formulierungen, Anwendungen

Triaxial constitutive laws for concrete – basics, formulations, applications The quasistatic behaviour of concrete is characterized by typical effects like increasing strength in triaxial compression stress states, strain softening and volume dilatancy with increasing demands, and furthermore permanent deformations upon unloading. Realistic calculation of the behaviour of reinforced concrete structures of these effects have to be properly described by corresponding constitutive laws. Different approaches basing upon damage and plasticity concepts and furthermore their potentials and limits are discussed. Conventional methods of continuum mechanics have to be extended in particular with respect to cohesive fracture mechanisms of concrete. Because of strain softening special requirements and methods arise to the application of concrete constitutive laws in numerical methods.     

Stahlbetonträger mit Öffnungen. Ein vereinfachtes Bemessungskonzept

Reinforced Concrete Beams With Openings – A Simplified Design Concept – A comprehensive design concept for reinforced concrete beams with large openings was presented in Beton‐ und Stahlbetonbau 97, booklet 3, 2002. In recent years six laboratory tests were carried out to verify the design concept. Additionally extensive Finite Element computations with physically nonlinear material models were conducted to analyse the structural behaviour of reinforced concrete beams with opening groups. In this paper a simplified design concept for reinforced concrete beams with large openings and opening groups is presented which is based on the results of the test series and the FE‐computations.     

Life‐cycle cost assessment of mid‐rise and high‐rise steel and steel–reinforced concrete composite minimum cost building designs

The traditional trial‐and‐error design approach is inefficient to determine an economical design satisfying also the safety criteria. Structural design optimization, on the other hand, provides a numerical procedure that can replace the traditional design approach with an automated one. The objective of this work is to propose a performance‐based seismic design procedure, formulated as a structural design optimization problem, for designing steel and steel–reinforced concrete composite buildings subject to interstorey drift limitations. For this purpose, eight test examples are considered, in particular four steel and four steel–reinforced concrete composite buildings are optimally designed with minimum initial cost. Life‐cycle cost analysis (LCCA) is considered as a reliable tool for measuring the damage cost due to future earthquakes that will occur during the design life of a structure. In this study, LCCA is employed for assessing the optimum designs obtained for steel and steel–reinforced concrete composite design practices. Copyright © 2011 John Wiley & Sons, Ltd.     

Entwicklungen im Stahlverbundbrückenbau – Autobahnbrücken mit einteiligen Verbundquerschnitten

Developments of steel‐composite bridges – motorway bridges with one‐piece composite cross‐sections. On design orders of the German Bundesministerium für Verkehr, Bau‐ und Wohnungswesen (BMVBW) motorway bridges have to be built with two superstructures – one for each carriageway. To get satisfying solutions in design of motorway bridges across valleys too, the authority decided in 1997 that it should be possible to build one‐piece steel‐composite bridges, provided that special suppositions are respected. The acceptance based on the condition, that it is possible to repair the reinforced concrete slap of the one‐piece superstructure as well as separated superstructures. The extensive maintenance of traffic has to be guaranteed all over the repair period. Since 1997 DEGES erected six bridges with one‐piece steel‐composite cross‐sections, three further bridges are under construction. Although the superstructures are designed for the state of the partly replacement of the reinforced concrete slap and therefore they are over dimensioned for the using‐state, these one‐piece superstructures are economic if they have a height of more than 50 m over the bottom of the valley. The following essay describes the one‐piece steel‐composite cross‐sections and gives constructive hints to their components.     

异形柱用于8度抗震设防建筑研究

通过混凝土异形柱框架和异形柱框架 -剪力墙结构的弹塑性时程分析以及总结异形柱和异形柱框架的部分试验成果 ,研究了异形柱用于 8度抗震设防地区房屋建筑的可能性 ,提出了 8度抗震设防建筑采用异形柱的设计建议     

Fuß‐ und Radwegbrücke aus Carbonbeton in Albstadt‐Ebingen

Pedestrian bridge made from carbon‐concrete in Albstadt‐Ebingen – First entirely carbon‐reinforced concrete bridge worldwide The bridge erected in Albstadt‐Ebingen in October 2015 is realized without any steel reinforcement or pre‐tensioning, making it the world's first entirely carbon‐reinforced concrete bicycle and pedestrian‐bridge. The trough section with material thicknesses of 70 mm (trough walls) and 90 mm (slab) respectively has been fabricated as monolithic pre‐cast element. With a span length of 15 m and a width of 3 m, the bridge‐deck requires no further coating and has a total weight of just 14 tons (approximately 310 kg/m2); this is about 50 % of comparable conventional reinforced concrete bridge‐decks. Besides material and weight savings, an exceptionally long service life with minimal maintenance can be expected, as the steel corrosion that is typical in reinforced concrete structures can be entirely avoided. Since the use of carbon‐reinforced concrete (carbon concrete) is not yet approved in Germany, the client had to obtain approval based on individual cases (ZiE).     

Seismic performance and cost‐effectiveness of high‐rise buildings with increasing concrete strength

The relationship between the seismic performance and economics of high‐rise buildings when designed to different material strengths is investigated in this paper. To represent the modern high‐rise construction, five 60‐story reinforced concrete buildings with varying concrete strengths, ranging from 45 MPa to 110 MPa, are designed and detailed to fine accuracy keeping almost equal periods of vibration. Detailed fiber‐based simulation models are developed to assess the relative seismic performance of the reference structures using incremental dynamic analyses and fragility functions. It is concluded that a considerable saving in construction cost and gain in useable area are attained with increasing concrete strength. The safety margins of high‐strength concrete in tall structures may exceed those of normal‐strength concrete buildings, particularly at high ground motion intensity levels. The recommendations of this systematic study may help designers to arrive at cost‐effective designs for high‐rise buildings in earthquake‐prone regions without jeopardizing safety at different performance levels. Copyright © 2014 John Wiley & Sons, Ltd.     

Projekt Steel Earthquake Design (SEQD) – Erdbebenresistentes Stahlbausystem für Wohnhäuser

The SEQD – Steel Earthquake Design – project for earthquake‐resistant residential buildings. The construction material steel is currently mostly applied in highly‐engineered structures like bridges, industrial halls or high‐rise buildings. The SEQD – Steel Earthquake Design – project had the aim of developing a safe and economic solution for small residential buildings in earthquake regions. The basic idea of the system is to combine an engineered steel frame as primary structure with non load‐bearing infill walls from local materials. The new design includes innovative connections between frame elements and special uniaxial couplings between walls and steel frame. Reinforcement of the infill walls is achieved by applying grids from synthetic materials. In October 2004 experimental tests on a prototype structure were carried out in an assembly hall of the Rudolstädter Stahlbau GmbH.     

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.     

Cyclic loading test of T‐shaped mid‐rise shear wall

Shear wall systems are the most commonly used lateral load resisting systems in high‐rise buildings. Six 1:2 scale mid‐rise T‐shaped reinforced concrete shear wall specimens with aspect ratio of 1.75, 2.15 and 2.80 were respectively tested under reversed cyclic loading. The seismic behavior and displacement ductility were investigated. The effects of aspect ratio, axial load level and transverse steel ratio on the seismic behavior and displacement ductility were also analyzed. Test results were discussed and compared with T‐shaped steel–concrete composite shear wall. Results mainly showed that the T‐shaped shear wall specimens mainly presented bending–shear failure mode and were all destroyed because of the concrete crushing at the web (negative direction) and the longitudinal reinforcement of the web reaching the limited deformation (positive direction), showing that the web was the weakest part of T‐shape shear wall. The ductility of the specimens was decreased, and the ultimate load‐bearing capacity was increased by increasing the axial load. To specimens with smaller aspect ratio and higher axial load ratio, the special transverse steel ratio of the web should be increased to improve the crushing strain of the confined concrete of the web in order to satisfy the ductility of the walls. The seismic performance was obviously improved in the T‐shaped steel–concrete shear wall compared with that of the T‐shaped reinforced concrete shear wall. Copyright © 2011 John Wiley & Sons, Ltd.     

Zur Mindestquerkraftbewehrung von Stahlbetonbalken

On minimum shear reinforcement amounts for reinforced concrete beams A ductile shear bearing behaviour of reinforced concrete beams is recently ensured by providing standardized amounts of minimum shear reinforcement in compliance with established detailing provisions. However, lower than minimum shear reinforcement amounts do not necessarily go along with a brittle mode of failure in all cases. Dependent on the individual layout and amount of stirrups, the contributions of other bearing capacities and the crack formation itself, the initial cracking force might be overtaken even along with further load gains and reasonable limited shear crack widths. Especially the latter one holds potential to rate the failure mode – brittle or ductile – on site. Experiments on lightly shear reinforced single span concrete beams are evaluated and rated with respect to minimum shear reinforcement amounts required. Thereby, special interest is set on the load‐deformation response obeying the critical shear crack and the structural design. Finally, the overall shear resistance as well as the stirrups' efficiency in the effective shear domain are analysed to derive suggestions for future practical application on‐site.     

Zur Ermittlung der Normalkraft‐Verlängerung und Moment‐Krümmung‐Beziehungen der Stahlbetonbauteile im Grenzzustand der Gebrauchstauglichkei

Die Nachweise zur Begrenzung der Verformungen von Stahlbetonbauteilen sind infolge der Verwendung von Baustoffen höherer Festigkeiten immer wichtiger geworden, oft sogar maßgebend. Eine Verdopplung der Betondruckfestigkeit eines normalen Betons ruft eine etwa 20%ige Erhöhung des E_c‐Moduls hervor aber keine des Betonstahls, da E_s konstant ist. Dies und die dementsprechend schlanker gewordenen Stahlbetonbauteile führen zu größeren Verformungen – Verlängerungen, Durchbiegungen und/oder Verdrehungen – die deren Verhalten beeinträchtigen können. Die für die Ermittlung der Verformungen benötigten “Normalkraft‐mittlere Dehnungslinien”, bzw. “Moment‐mittlere Krümmungslinien” werden erläutert. About the Calculation of Displacements of Reinforced Concrete Members in the Serviceability Limit State The verification of reinforced concrete elements for the purpose of limiting deformations has become increasingly important, often even decisive, as a result of the use of higher strength materials. A doubling of the compressive strength of a normal concrete causes an increase of about 20% in the E_c‐module, and none of reinforcing steel, because E_s is constant. This and, accordingly, the slender reinforced concrete elements lead to larger deformations – elongations, deflections and/or rotations – which may affect their behaviour. The determination of “axial tensile force – mean strain diagrams”, respectively “bending moment – mean curvature diagrams”, needed for the calculation of the displacements, is explained.