Talbrücke Elben – Eine Stahlverbundbrücke mit einteiligem Querschnitt

Viaduct Elben – A steel‐composite bridge with one‐piece cross‐section. In the north of Siegen a non existing section of the German motorway Autobahn A 4 and of the federal highway B 54n, also called “Hüttentalstraße”, was completed during the last years. The 432 m long viaduct – called “Talbrücke Elben”, as an important element in the construction for the extension of the A 4, is in particular interesting because of its design and its construction itself. During the last years about 10 similar constructions have been implemented, others are currently planned. Therefore, it seems appropriate to report about the experiences with steel‐composite bridges in general and particular, always having the bridge “Talbrücke Elben” in mind. Furthermore, the paper intends to give an overview on further fields of application in the near future.     

Die Stahlverbundbrücke über die Müglitz im Zuge der Autobahn Dresden–Prag – Entwurf und Ausführung

The composite bridge across the Müglitz on the highway Dresden–Prag. Design and construction. The bridge across the Müglitz transfers the newly built Federal Highway A17 over the small town Dohna near by Dresden. The bridge has a total length of 310 m and crosses a railway, a state highway and the river Müglitz. The bridge dominates the townscape. Extensive design investigations were performed to find the technically and aesthetically right solution for the given situation. Chosen and built was a continuous girder bridge as a composite structure with a span sequence of 45 – 55 – 55 – 55 – 55 – 45 m. The construction is composed of two bridges, one for each carriageway. Each superstructure has two airtight steel box girders, which are in composition with the concrete deck slab. To give the bridge a differentiated view, the main girders are built with shallow but significant haunches and emphasized stiffening boxes in the bearing zones. In the design of the composite columns these criteria reappear in the widening of the column heads and the eight‐cornered cross‐sections. Special consideration was given to a simple fabrication and an unproblematic erection with as far as possible reduced welding at the site. The article covers the planning and the building of the bridge. In addition experiences made in building other bridges with airtight box girders are reported.     

Stahlverbundbrücken mit begehbaren Kastenträgern

Steel‐Composite bridges with box girders which are to be inspected on foot. In the last years the development in shaping of cross sections of bridges over a valley shows a tendency to some special types in dependency on the site, which were built again and again. These are the cross sections with one trapezoid box girder, consisting of a steel trough and a concrete slab, which is to be inspecting on foot as well as cross sections with two airtight welded box girders of steel, connected with the concrete deck slab, too. All the bridges with these cross sections are so designed that there is only a composite effect in longitudinal direction. To realise an economical bridge building, there has to be taken some typical design criterions into consideration for each type of cross section. The following paper describes these design criterions for cross sections with one trapezoid box girder and points out the optimal cross section and the economical area of application.     

Hybridbrücken mit blockverleimtem Brettschichtholz

Hybrid bridges with log‐glued‐laminated timber. In Germany, timber as load‐bearing element of bridges is only used for the construction of foot‐ and bicycle viaducts. The development of new timber‐based products and modern technologies gives interesting chances for timber bridge‐building in future. Main beams with high stiffness and stability of dimension can be produced by log‐glued lamination of timber. Efficient hybrid cross‐sections of superstructures as timber‐concrete‐composite constructions can be made by the combination of beams consisting of log‐glued‐laminated timber and concrete deck slab. For road bridges, these hybrid cross‐sections could be used alternatively to conventional methods of construction. The following paper gives a review of the development status of timber‐concrete‐composite construction in bridge building and shows static and constructive specifics.     

Zur maßgebenden Verkehrslaststellung bei Schrägseilbrücken

Appropriate traffic load cases for steel and composite cable – stayed bridges. A significant problem in the global analysis of bridge structures is to find the most unfavourable position of the traffic loads for each cross‐section. In practice usually those traffic load cases are chosen which maximise one part of stresses at the cross‐section (often expressed in form of internal forces). First of all a simple method is presented to find out the most unfavourable traffic load position, also applicable for complex interaction formulae including web buckling. Secondly an example of a cable‐stayed bridge is analysed. For two significant sections of the bridge deck the results are presented. The stresses due to the conventional practical procedure are compared with the more accurate ones. The behaviour is explained by the corresponding influence lines. Based on these results some proposals for practical work are given. The presented procedure is also applicable to other types of construction works and materials (e.g. reinforced concrete).     

Erneuerung von Großbrücken im Zuge hoch belasteter Autobahnen – Randbedingungen und Lösungsansätze am Beispiel der Urselbach‐Talbrücke

Renewal of highly frequented large‐scale motorway bridges. The bridge over the Urselbach – edge conditions and solutions. The newly built bridge across the Urselbach, which has a total length of 332 m, is part of the Federal Highway A5 near Frankfurt. The construction is composed of two bridges, one for each carriageway. Each superstructure consists of two steel box girders. Over these steel box girders, and resting on their top flange, is a cast‐in‐place concrete slab that becomes a part of the roadway. For a future renewal of the concrete slab it is requested that eight traffic lanes still have to remain during reconstruction. As one superstructure is passed by maximum six traffic lanes, the other must still be partly passable during its renewal. That's why the concrete slab can be demolished partly and afterwards concreted if it's necessary. Therefore the composite construction offered many advantages. The form of composite construction of the bridge across the Urselbach results from the combined action of structural steel and a concrete deck slab, which has the function of a replaceable structural member under traffic use. This conception was achieved by a structural analysis taking the substantial influences into account and the arrangement of some additional structural parts. The found solution should give some ideas on the way to a technical guide‐line for dimensional and structural design of concrete bridges with replaceable deck slabs.     

Der Viadukt über das Tarntal bei Millau – Von den ersten Entwurfsgedanken bis zur Fertigstellung

The viaduct over the Tarn valley near Millau – from early design to completion. The erection of the viaduct over the Tarn valley near Millau in central France began in October 2001 and was completed in December 2004. The viaduct with an overall length of 2460 m covers six 342 m long main fields, those at seven suspension towers is embodied and represents an important progress in design of cable‐stayed bridges. The motorway runs in 270 m height over the river, two of their columns are more highly than 230 m. Together with the 87 m high pylons over the roadway towers are higher then the Eiffel tower in Paris. Two solutions were prepared, one in prestressed concrete and one in steel construction method.     

Die Svinesundbrücke – Besonderheiten bei Entwurf,Fertigung und Montage der Stahlkonstruktion

The Svinesund‐Bridge – Particularities of design, fabrication and erection of the steel superstructure. In the course of the restructuring to highway standards of the existing roadway E 6 connecting Gothenburg in Sweden to Oslo in Norway a new spectacular crossing of the Svinesund exactly located at the border between the two neighbouring countries was constructed. The two separated superstructures of the 704 m long bridge which consists of pure steel box sections are crossing the beautiful Fjord‐landscape without any visible direct supports and therefore appear particular audacious and transparent. Both the concrete columns on both sides of the Svinesund and the huge concrete arch over the Svinesund are purely located in the 6 m wide open space between the two steel superstructures and herewith render this bridge its unique appearance. Following the particularities of design, fabrication and erection of this outstanding steel structure will be described.     

Stahl‐Beton‐Haftverbindungen für Verbundbrücken – Versuche und Bemessung

Connections by adherence for steel‐concrete composite bridges – tests and design. This paper presents experimental and analytical research that was conducted on new connections “by adherence” for steel‐concrete composite bridges. Their resistance is due to the frictional shear resistance of different interfaces positioned in a judicious manner. These connections makes it possible to erect the structure quickly with full‐depth precast concrete slabs, while the concreting works on site are as much as possible limited. Experimental results show that these connections exhibit a high resistance to horizontal shear forces and are very stiff compared to traditional connectors (headed studs). However, their ductility is limited. Based on the experimental results, a calculation model, taking into account the deformation observed during the tests and behavior laws for interfaces, was then developed and used in a parametric study. Some results are presented and discussed. A simplified method for determining the resistance of these connections, based on these results, some design rules as well as some recommendations for construction are finally proposed. The behavior of steel‐concrete composite beams with connections by adherence is also shortly discussed.     

Ermüdungssicherheit für Stahlbeton unter Temperaturzwang: Einsichten für Praktiker

Fatigue safety for reinforced concrete subjected to temperature stress. Fatigue‐safety analysis is sometimes design‐relevant for reinforced concrete bridges. The importance of temperature stress in statically‐indeterminate structures will be overestimated if the effective stiffness of cracked cross sections is assumed unnecessarily large and the resultant stress amplitudes are taken in full strength to be relevant for fatigue. Simple but fundamental considerations reveal the underlying physical relationships und make it possible to determine the influence of temperature stress on fatigue safety in a realistic fashion.     

Instandsetzung einer “müden” Straßenbrücke mit orthotroper Fahrbahn

Repair of a “tired” road bridge with orthotropic deck. The proneness to fatigue of steel bridges with an orthotropic deck appears in many damages because of the increasing traffic of heavy vehicles. On the example of an aggrieved highway‐bridge the specific weak points and the executed damage analysis will be shown. The gained knowledge leaded to the development of different alternatives of repair and to the presented repair concept. To improve the global characteristics of the structure additional supports will be built, for the local strengthening a reinforced concrete slab will be built as composite structure with the existing steel deck.     

Trag‐ und Ermüdungsverhalten liegender Kopfbolzendübel unter Quer‐ und Längsschub

Structural and fatigue behaviour of horizontally lying shear studs subjected to vertical and longitudinal shear. In consideration of structural, manufacturing and economic aspects new interesting composite cross sections for buildings and bridges consisting of reinforced concrete and structural steel lead to a horizontally lying arrangement of headed shear studs influenced by edge proximity. Compared to common vertical shear studs the relatively small distance of horizontally lying shear studs from the edge of the slab leads to different bedding conditions of the connectors within the surrounding reinforced concrete material, which results in differing structural and fatigue behaviour of this type of shear connection. For future applications of horizontally lying shear studs on the basis of experimental and theoretical investigations design rules for the shear connection subjected to monotonic vertical shear, monotonic vertical and longitudinal shear and cyclic longitudinal shear are presented.     

Der Stabbogen bei stählernen Straßenbrücken – Entwicklungstendenzen der letzten 50 Jahre – Teil I

The strut arch in using of steel road bridges mainly in Germany – trends of developments into the last 50 years. By the presentation is given a survey about the development of the designing the arch construction for steel road bridges inclusive the constructive details. In the detail are considerd the suspensions with their connections, the cross‐sections of the arch, springing arch, arch model and the roadway‐constructions into different phases. At last of the investigation are presented some typical erection‐examples.     

Der Stabbogen bei stählernen Straßenbrücken – Entwicklungstendenzen der letzten 50 Jahre – Teil II – Fortsetzung aus Heft 2/2005 und Schluß

The strut arch in using of steel road bridges mainly in Germany – trends of developments into the last 50 years. By the presentation is given a survey about the development of the designing the arch construction for steel road bridges inclusive the constructive details. In the detail are considerd the suspensions with their connections, the cross sections of the arch, springing arch, arch model and the roadway‐constructions into different phases. At last of the investigation are presented some typical erection‐examples.     

Das neue Bewehrungssystem; Druckglieder mit hochfestem Betonstahl SAS 670/800

The New Reinforcement System; Compression Members With High Strength Reinforcement SAS 670/800 Part II: Opernturm Frankfurt – Application In Frankfurt am Main, the Opernturm, a sophisticated 46‐storey tower block project, is presently being constructed in the immediate vicinity of the Alte Oper. In designing the 169 m high Opernturm, dimensioning of the highly loaded columns presented a particular challenge. For architectural reasons, the cross sections of the mega‐columns in the Opernturm's 5‐storey high lobby were to be as small as possible. Using standard reinforcement steel this requirement could only have been built by utilizing highstrength concrete. It was however economically more efficient to construct these columns using standard concrete (C50/60) and high‐strength reinforcement steel (SAS 670/800) from the Annahütte Steel Works. Construction of the highly loaded façade columns presented a similar challenge. For architectural reasons and due to building services requirements as well as to increase floor space they too were to have as small cross sections as possible with large slendernesses (λ > 85). Also in this case, reinforcement using standard reinforcement steel would not have been possible without the cost‐intensive use of high‐strength concrete. For this reason, the highly loaded façade columns were also reinforced using SAS 670. Part I of this report published in issue 5/2008 discussed the technical principals of columns using S 670. Part II deals with the design of the Frankfurt Opernturm, the construction of the highstrength columns and the requisite construction approval on an individual basis.     

Die Wupper‐Talbrücke Oehde – eine moderne Verbundbrücke

The Wupper River valley bridge – a state‐of‐the‐art composite bridge. The German motorway Autobahn A 1 is one of the nation's most important and frequently traveled highways, connecting the country's northern and southern regions. The road currently has two lanes in each direction, which do not provide enough capacity to carry the traffic volume without daily traffic jams and heavy delays. Therefore, the federal government and the Northrhine‐Westfalia Department of Transportation decided to ease the situation by adding one lane in each direction. This total of 6 lanes fits into the master plan of widening major highways around the Ruhr River region. North of Cologne, the Autobahn A 1 crosses mountainous terrain, so several bridges with total lengths between 240 and 420 meters have had to be widened, replaced, or, most commonly, supplemented by a new bridge. Such supplementation was used on the Wupper River Valley Bridge, called Oehde, close to the city of Wuppertal. The bridge illustrates an example of modern composite bridges adopting new methods in construction and design, and also marks an outstanding example of current composite structures in Germany.     

Untersuchungen und theoretische Modelle von druckbeanspruchten Stahlstützen in Verbundbauweise

Experimental and analytical modelling of steel columns reinforced by concrete encasement. Experimental investigations of steel‐concrete axially compressed columns that were tested in the Laboratory of the Institute of Building Structures of the Warsaw University of Technology are presented. The results of conducted experimental work created a basis for the detailed investigations into the appraisal of the influence of different factors associated with the behaviour of tested elements. Analytical modelling was done with use of the finite element method and the ABAQUS software. In the analysis, the emphasis was put on the influence of those factors that have the most important effect on strength and deformability of composite columns. As to the authors' knowledge, the investigated factors have not been accounted for accurately enough in current design codes. The factors such as the load application to the composite column end and the restraining conditions at the supports are among those most important from the design point of view. The investigations have a great practical aspect at this particular moment when in Poland there is an ongoing discussion associated with the proposed new national code on design of composite steel‐concrete structures. The said codification proposal is an attempt to harmonize the national design rules with those applied in the Eurocode 4. The experimental part was concerned with testing of 16 composite columns that were made as completely encased steel I‐type elements (HEA160 section used). The main sectional dimensions were 260 mm × 260 mm, and the column length – 2500 mm. In addition, the reference steel column of HEA160 section was tested. The parameters that were being changed during experiments consisted of the following ones: the way of the load application to the column end face, compressive strength of the concrete encasement and the restraining effect at the supports that reproduced that of assumed in the numerical studies. The behaviour of composite columns with fibre‐reinforced concrete heads was also investigated. The comparison of load deflection curves from the experiments and those from the computer modelling was carried out. In addition, failure loads from the laboratory tests were compared with those calculated according to some chosen design codes. The analysis carried out proven that both the way at which the load is applied to the element end face and the type of end restraints had a great influence on the strength of composite columns. It is clear from the experiments that in case of load application directly through the steel section, the attainment of the limit state of cracking was much earlier than the strength ultimate limit state, so that it controlled the design of composite columns. In this case, an increase in strain of steel sections was observed. In addition, the rigid restraining conditions at the column ends resulted in a decrease of the load bearing capacity because of the stress concentration in the concrete encasement within the support zones. The failure of composite columns was controlled by the combined stress state in the concrete encasement. The study carried out has shown that the load bearing capacity of composite columns can be substantially increased by the applications of fibre‐reinforced column heads at their end supports. The strength of such columns increased by 30–48% if compared with the same composite columns but made without fibre‐reinforced ends.     

Querschnittsberechnung von Stahlbetonstäben – Stand der Forschung

Cross‐Sectional Analysis of Reinforced Concrete Beams – State of the Art Many common structures consist of one‐dimensional members. For such structures beam theory is applicable. Within beam theory, the material behaviour can be captured on cross‐sectional level. Regarding reinforced‐concrete structures, material nonlinearity has generally to be considered. The present article provides an overview of the state of the art in cross‐sectional analysis of one‐dimensional reinforced‐concrete elements. A crosssectional analysis describes the relationship between the internal forces and the generalized strains. There is a large number of different models, for which a classification is suggested here. Existing models can be classified into resultant models, truss models, uniaxial models, wall models, and finite element models. For each class, the characteristics are outlined and the most important models are presented.     

Aktuelle Entwicklungen im Straßenbrückenbau

Current developments of road bridges in Germany. In connection with the major tasks after the reunification of Germany for the creation and improvement of the traffic infrastructure in the East German States an exceptionally large number of bridges and other transportation structures have newly been built or have been rehabilitated in connection with the widening of Freeways. The engineers in charge took up this opportunity quickly to initiate new technical developments and to realize innovative solutions. This is true for reinforced and pre‐stressed concrete bridges as well as for steel composite bridges in particular. Many good examples for current bridge design were built especially for the Freeways A71/A73 across the Thuringia Forest and for the A4 around Dresden. At the same time the German national codes were replaced by the modern European Eurocodes so that the state‐of‐the‐art of bridge design in Germany today is compatible with international standards.