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.     

Versuche an genieteten Brückenlängsträgern – Statisches Verhalten,Ermüdungsfestigkeit und Rissausbreitung

Tests on riveted bridge stringers – behaviour under static loads, fatigue strength and crack propagation. The assessment of the load‐carrying capacity and of the remaining fatigue life of existing railway and road bridges has gained an increasingly significant role over the last years. Thus, the problem of determining adequate strength values of riveted members of older steel bridges once again arose during the elaboration of the ONR 24008 specification. In the course of a research project initiated by the Austrian Federal Railways (ÖBB), static and fatigue tests were carried out on riveted members taken from a demolished railway bridge in Salzburg. The results of these tests gave further insight into the load carrying behaviour of built‐up riveted members, particulaly the progagation of fatigue cracks.     

Verbundbrücke Pöcking – Innovative VFT‐Träger mit Betondübeln

The new road bridge over the railway line next to Pöcking applied to a new construction method for composite bridges. The VFT®‐construction method, which has been established in Germany within the last years combined with concrete dowel technology, generated a new type of prefabricated composite girders. Concrete dowels, which are manufactured by special steel web cuts connect rolled steel profiles with pre‐cast concrete members. An increasing degree of standardisation and prefabrication enables the application with an economic use of resources and a high quality level. This article describes design and manufacturing aspects of the new bridge, which is already under traffic use.     

Statistisch begründete Festigkeitskennwerte genieteter Bauteile – statische Festigkeit und Wöhlerlinienkatalog

Statistically founded strength values of riveted members – static strength and fatigue life classification of constructional details. The assessment of the load‐carrying capacity and of the remain‐ing fatigue life of existing railway and road bridges has gained an increasingly significant role over the last years. Thus, the problem of determining adequate strength values of riveted members of older steel bridges once again arose during the elaboration of the ONR 24008 specification. In the course of a research project initiated by the Austrian Federal Railways (ÖBB), results of static and fatigue tests carried out on riveted members were evaluated statistically. With regard to fatigue test data, a classification of riveted details with consideration of different constructional details proved to be sensible and to lead to more consistent S‐N design curves. Tables containing static strength values and a catalogue of S‐N design curves based on constructional detail classifications represent the result of the research project.     

Die Netzwerkbogenbrücke,ein überaus effizientes Brückentragwerk – Tragwirkung und Konstruktion

The network arch bridge, an extremely efficient structure – Structural behaviour and construction. In difference to popular tied arch bridges with vertical hangers the arch and lower chord of network arch bridges are connected with inclined hangers. These hangers are placed in such a way that they intersect among each other at least twice. Furthermore more hangers will be used. So the distances between the connection points at the arch and the lower chord are substantially smaller than in the case of classical tied arch bridges. There are two reasons for the use of such a network. The first point is the advantageous structural behaviour of inclined hangers if the bridge is only partially loaded. Secondly the bending moments in arch and lower chord will be strongly reduced. In fact of this a slender structure and a saving of 20% of the structural steel is possible. In the present paper the structural effect and the construction of this bridge type will be explained. Finally a comparison between vertical and inclined hangers is shown to clarify the advantages of network arch bridges.     

Großversuch WILD‐Brücke – versuchsgestützte Bemessung einer UHPC‐Bogenbrücke

Full‐Scale Experiment Bridge WILD – Design of an UHPC Arch Bridge based on Experiments The outstanding durability of UHPC makes this material predestined for the construction of bridges. In Austria UHPC is introduced into the practice of road bridges through the realisation of the bridge WILD. The cross section of the arch, which spans 70 m, is just 6 cm thick and doesn't contain any passive reinforcement. The design is based on international recommendations on the one hand and on specific experiments on the other hand. This paper deals with the evaluation of two full‐scale laboratory tests. The setup is configured for getting a broad field of results as it is necessary for approval tests. In this way, all critical design states, which are also determined by calculation, are investigated experimentally. Furthermore, the experiments cover secondary effects, which don't have any verification through practical experience but can clearly be seen in FE‐results. The test results are carefully interpreted and explained by the use of simple mechanical models. The final examination of the results is figured out by means of comparison between calculation and experiment.     

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.     

Instandsetzung und Verstärkung von Stahlbrücken mit Kategorie‐3‐Schäden

Reinforcing steel bridges with category 3 damages – report on a BASt research project. In recent years, fatigue damages have been observed at the main supporting structure of steel bridges, the orthotropic decks, as well as the transverse structure of steel bridges (the so‐called category 3‐failure). The rapidly increasing road traffic intensifies the situation resulting in a huge amount of steel bridges affected by fatigue damages. Existing steel bridges with category 3‐fatigue cracks have been intensively investigated. Fatigue failure modes and general evaluation criteria have been summarized, analysed and categorized, in order to enable first fundamental and time‐efficient definition and classification of category 3‐damages. FE‐simulations of transversal steel bridge structures (with and without reinforcements) have been carried out to evaluate and review the structural bridge concepts. Based on these studies, a special way of the steel bridges' maintenance has been followed up, which is removing all possible transversal bracings. Finally, different options of maintenance and repair have been investigated both newly and successfully applied in the recent past. Appropriate actions for solving essential category 3‐fatigue problems are presented.     

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.     

Regen‐Wind‐induzierte Schwingungen – ein State‐of‐the‐Art Report

Rain‐wind induced vibrations can occur, when rain and wind simultaneously act, for instance, on the cables of cable‐stayed bridges, on inclined steel hangers of arch bridges or on the backstays of guyed masts. As a result of wind and gravity, the rainwater forms small rivulets, which flow down on the surface of these structural members. The rivulets disturb the wind flow around the dry cross section and cause a modified unsymmetrical distribution of the surrounding wind pressure, which leads to periodic exciting forces. Due to the movement of the cable and the wind forces, the position of the rivulets varies on the cable surface. This constellation can lead to aeroelastic excitation with large amplitudes. Rain‐wind induced vibrations can reduce the life cycle of a structure seriously, because the initialising wind velocity of rain‐wind induced vibrations is significantly lower than the design wind velocity and thus has a high probability of occurrence. In this paper, the further researches and investigations up to now dealing with rain‐wind induced vibrations are summed and commented.     

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.     

Bewertung bestehender Natursteinbogenbrücken

Assessment of existing natural stone arch bridges. Arch bridges made of natural stone masonry rank among the oldest structures still in full function within road and railways. With a age from partly far over 100 years these represent historically very valuable built volumes in large number of several thousand buildings at the same time. The oldest existing bridges based on empirical values design, later there were graphic procedures for structural design, one developed approximation formulas on basis of the arch line of thrust for the draft of substantial geometry parameters such as span, type of arch as well as arch thickness at the crown and springing. In the course of the revision of these buildings evaluations regarding load‐carrying capacity and serviceability on the basis are demanded under today valid loads and standards. In this paper apart from a short overview to the existing arch bridges the possibilities of the structural modelling are discussed. An emphasis forms the computation of the masonry load‐carrying capacity, which is described in particular by safety considerations. The procedures referred to the bridge construction are transferable in principle to other structures of building construction.     

钢—混凝土组合桥混凝土徐变收缩分析

本文介绍钢混凝土组合桥梁混凝土徐变、收缩分析的方法,研究内容涉及结合梁桥及钢管混凝土组合拱桥。文末给出了可供参考的结论     

Die Geh‐ und Radwegbrücke Kehl – Strasbourg

The Pedestrian and Cycle Bridge Kehl – Strasbourg. The Rhine bridge between Kehl and Strasbourg is the new regional landmark and linking element of the International Gardening Show. The approach to unifying different functions and an architectural endeavour lead to a unique structural system. Two separate decks address the different situations on the river banks and, linked by a platform, form a balcony above the Rhine at midspan. The main bridge is a cable‐stayed structure with a steel pylon and a steel‐concrete composite deck. The approach bridges are continuous girders on steel columns. Both pile and flat foundations are featured in the design. The article describes the structural concept and design, outlines the erection procedure and discusses aspects of the dynamic behaviour of the bridge.     

Holzbrücken – Erkenntnisse zum Feuchteverhalten in den Tragquerschnitten aus Langzeitmessungen

Timber bridges – Long term monitoring results of moisture diffusion in the load carrying cross‐sections Timber road bridges have been built worldwide for centuries. The high performance of wood is approved through many constructions. However, there are still doubts about using wood by the planning engineer, which reduce the number of realized projects. The moisture induced stresses in cross‐sections according to the varied ambient climate are mainly investigated under laboratory conditions. The results show that the moisture content changes differently over the cross‐section and leads to moisture induced stresses. The discussion about methods for the assessment of the moisture induced stresses in timber bridge cross‐ections is continuing. Results observed in the long term monitoring of seven timber bridges provide first guidelines for practitioners. For all constructions, the moisture content was measured regarding the ambient micro climate. As result, the influences according to the ambient micro climate are not insignificant. Positive is that the directly measured moisture content is less compared to the equilibrium moisture content calculated from the data of a close by meteorological station. The analysis of the moisture gradient over the cross‐section allows the definition of an active or passive zone.     

Orthotrope Fahrbahnplatte – Entwicklungen und Möglichkeiten für die Zukunft

Orthotropic decks – developments and future outlook. Bridges with steel orthotropic decks, first introduced in the 1950s in Germany, have been subsequently built in other countries, with several thousand of such structures now in service throughout the world. The performance record of orthotropic decks has been satisfactory, excepting occasional fatigue cracking which had occurred on some decks built in the 1960s and 1970s, mainly caused by inappropriate details and fabrication defects. Specific causes of such failures are discussed. Developments of design methods for orthotropic decks are discussed. For basic design simplified approaches, such as the Pelikan‐Esslinger method, are generally used. The applicability of the classical (Wöhler's) fatigue theory is limited. Therefor current design specifications permit empirical fatigue safety assessment by conformance with approved geometric standards. Due to their light weight, durability and load carrying capacity, orthotropic decks have a promising future being indispensable in the super‐long span bridges. Because of their capability for being structurally integrated with the main members of the existing steel bridges, orthotropic decks are also excellently suited for replacing the deteriorating concrete decks. In the U.S. nearly 40% of highway bridges are now considered “structurally deficient” or “functionally obsolete”, with failed concrete decks accounting for about two‐thirds of the deficiency cases. Several major U.S. bridges have recently received new orthotropic decks. Special problems encountered with redecking are discussed.     

SPS – ein neues Verfahren zur Instandsetzung und Ertüchtigung von stählernen orthotropen Fahrbahnplatten

SPS – an innovative method for the repair and refurbishment of orthotropic deck‐plates of steel‐bridges. This contribution describes how the new SPS‐Overlay technology has been applied in a pilot project for the refurbishment of orthotropic deckplates of road bridges in Germany. The main reason for such a refurbishment of orthotropic deckplates that have been designed and executed according to modern design rules as in EN 1993‐2 and that after 40 years of use have not yet exhibited any considerable fatigue damage is to make provisions for the current enhancement of traffic loads and traffic volume that could cause fatigue in the near future. The stepwise procedure to study the experience made with the SPS‐technology in the ship‐building area first, then to apply it to the retrofitting of damaged deckplates of a temporary bridge system (D‐Bridge) to gain experiences before it is used for retrofitting the deck of an old metro‐bridge in Berlin and to enter into the refurbishment of a bridge in the highway (Schönwasserparkbrücke near Krefeld) is explained in detail. Particular challenges for the use of the SPS‐technology for a highway bridge were: –·applicability on site under climate conditions –·fast execution to reduce restraints to traffic –·applicability of the guss asphalt layer with 75–80 mm thickness with a temperature of 225 °C without damaging the PUR sandwich core. The paper presents the technical developements including details of the scientific support, to justify the solution chosen toward the regulatory authorities. In conclusion the SPS‐technology has proved to be an efficient refurbishment method that meets all requirements.     

VFT‐WIB‐Brücke bei Vigaun – Verbundbrücke mit externer Bewehrung

VFT‐WIB viaduct in Vigaun – a composite bridge with external reinforcement. With the introduction of the composite dowel the possibility is given to develop new construction methods for bridges. The VFT‐WIB construction method is used for the first time for the road bridge in Vigaun/Austria, which is in service since autumn 2008. The cross‐section is composed out of two prefabricated elements with halved rolled girders, working as bottom flange. The composite dowels are manufactured by cutting the rolled girder into two halves with a special cutting‐line. These halved girders work as external reinforcement, which leads to very slender and economical composite structures. Below details about the planning process, the design and the construction process of 78m long three span framing bridge over the railway line from Salzburg to Wörgl are shown.     

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.     

Brückenbauwerke mit Stahlhohlprofilen – Konstruktive Ausführung

Design and construction of bridges with circular hollow sections. In the last years the field of modern bridge construction has been complemented by elegant truss structures made of circular hollow sections. However the realization of these bridges is implied with an extraordinary expense rooted in the absence of adequate design rules. Therefore two research projects have been initiated in order to examine bridge‐relevant construction details. The present contribution describes the results of the performed research work.