The deck plate of steel orthotropic bridges is loaded in fatigue by traffic. Increases in both the traffic intensity and the magnitude of the wheel loads have caused premature fatigue cracking of steel bridges in the Netherlands, mostly on very busy motorways. Overlaying the steel orthotropic bridges with 50 mm of heavily reinforced concrete has proved to be a suitable way of reducing the steel stresses at critical locations in the steel deck plate of fixed bridges. This repair method adds no weight to the bridge because the asphalt is simply replaced by a concrete layer.
The self-weight of the overlay has to meet strict demands in the case of movable bridges because the wearing surface is only a few millimetres thick. Reducing the depth of the overlay might be effective provided the reinforcement is not susceptible to corrosion. Suitable types of reinforcement were researched in an earlier study in which the bending stiffness of the composite structure, the strength of the steel-concrete interface layer and the bond between the reinforcement and the concrete were investigated in static experiments. The study of the fatigue behaviour of the composite section (concrete layer + steel deck plate) will be discussed in this article.

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The use of reinforced concrete (RC) piles in integral abutment bridges (IABs) has not been widespread due to concerns over pile flexibility and the potential for concrete cracking. This is the reason why the use of steel piles is the preferred solution in the United States. However, in various countries where IABs are still seldom used, RC piles are more readily available and economical. Hence, an understanding of the behaviour of IABs with RC piles can lead to a wider implementation of integral solutions. This paper presents the results of a parametric study conducted to evaluate how both the design variables and the accuracy of the modelling approach influence the potential use of integral solutions with RC piles in prestressed concrete bridges up to 200 m long. Finite element modelling was used and four levels of approximation (LoA) were established for the analyses, ranging from simple linear-elastic to more complex non-linear models. The results show that existing concerns over concrete cracking control can be overcome if adequate options in design are used together with the adequate LoAs in structural analysis. Integral solutions with RC piles for bridges up to 200 m long can generally be adopted, although in comparisons with non-integral designs a significant additional amount of prestressing steel is to be expected. The results also include a set of charts with practical estimates to help designers in their first approach to the preliminary design of an IAB.

In modern bridge construction, steel-concrete composite structures with composite dowels are being built more than ever, especially for small and medium spans. In contrast to headed studs, in which initial steel cracks occur after only a few load cycles [1], [2], the lifetime of composite dowels is characterized by the compression of the multi-axially stressed concrete in front of the composite dowel. Here, plastic compression strains occur in the concrete and accumulate over load cycles, leading to a cyclic increase in relative displacements in the connection. Certain proportions of these relative displacements, called inelastic slip, remain in the connection, even after the loading is relieved. The inelastic slip changes the characteristics of the static dowel curve. The initially rigid connection degrades over its lifetime, leading to redistributions of internal forces, which may be critical for fatigue design. In order to consider the degradation of the composite connection, a cyclic dowel curve can be used, which may be developed from the static dowel curve by introducing the inelastic slip. This paper presents the results of cyclic shear tests on different composite dowel geometries. The effect of load-dependent parameters (upper load level and load range) was investigated. Furthermore, an engineering model for determining the cyclic dowel curve is presented, which was developed based on the results of experimental and numerical investigations.

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The European Macroseismic Scale 1998 - (EMS 98) is an instrument for the natural hazard of earthquakes, which allows the explanation of observed differences in the behaviour of the prevailing construction types by introducing and implementing vulnerability classes. The EMS 98 enables also the identification of purely empirically justified ranges of scatter.
The basic methodology is also applicable to other natural hazards such as flood, tsunami and wind. This permits the development of a unified methodology for the consideration of building vulnerability in the sense of a multi-hazard approach.
For the first time, a vulnerability-oriented instrument is available to evaluate a building stock for different natural hazards according to criteria that have been standardised in terms of engineering.
The multi-hazard vulnerability with its possible scatters is examined and visualized on real building inventories.
With the concept of “LEGOisation” the existing buildings, a novel approach is presented to allow the sub-structuring of buildings into storeys (including roof, basement and floors) to further development of the classification towards specific damage characteristics and local vulnerability.
A still to be developed “Conceptual Simulation Tool” is described as an outlook. This uses the tools and methods developed to simulate damage and losses as a result of various natural hazards and their sequences.

The Koralm tunnel forms the central part of the route of the Koralmbahn railway from Graz to Klagenfurt in the section Deutschlandsberg- St. Andrä. The tunnel, split into three construction contracts (KAT 1,2 and 3) connects the federal states of Carinthia and Styria in Austria with a length of 32.8 km. Continuous tunnelling is intended for the section through the central mountain complex of the Koralpe. The very variable geological conditions (rock and loose ground sections, overburden of up to approx. 1,200 m, possible high water pressures and pronounced zones of faulting and fracturing) represent a major challenge for the implementation of mechanical tunnelling (tunnelling, lining and logistics concepts). The present article discusses the geological and hydrogeological conditions as well as the basic concepts for support and machine system and the particular measures to overcome squeezing rock conditions.

Der Koralmtunnel bildet das zentrale Trassenstück der Koralmbahn Graz-Klagenfurt im Abschnitt Deutschlandsberg-St. Andrä. Der in drei Baulose (KAT 1, 2 und 3) gegliederte Tunnel verbindet auf einer Gesamtlänge von 32,8 km die Bundesländer Steiermark und Kärnten in Österreich. Für die Durchörterung des zentralen Gebirgskomplexes der Koralpe sind kontinuierliche Vortriebe vorgesehen. Die stark wechselnden geologischen Randbedingungen (Fest- und Lockergesteinsabschnitte, Überlagerungen bis ca. 1.200 m, mögliche hohe Wasserdrücke sowie ausgeprägte Störungs- und Zerrüttungszonen) stellen höchste Anforderungen an die Realisierung des Maschinenvortriebs (Vortriebs-, Ausbauund Logistikkonzept). Im vorliegenden Beitrag werden die geotechnischen und hydrogeologischen Randbedingungen analysiert sowie die Grundkonzepte für Ausbausicherung und Maschinensystem und die besonderen Vorkehrungen zur Bewältigung der druckhaften Gebirgsverhältnisse vorgestellt.

In recent years the fixing of windows in masonry, in particular in hollow or perforated masonry with thin webs and/or insulation filling, has become a demanding task for which a prior structural design is recommended. For the design of a modern window fixing, a test-based calculation model was developed on the basis of which an approval was granted.
This article was first published in Bautechnik 95 (2018), issue 4, pp. 296-307.

Entwicklung einer neuartigen Bohrplattform in Form eines am Meeresgrund gelagerten Pendels. Es wird die technische Auslegung und die Anforderungen an die Technologie vorgestellt.

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Die Arbeit behandelt die Struktur, die Handhabung und den Inhalt eines Programmsystems zur Berechnung von Baugrubenumschliessungswänden. Es wird besonders auf folgende Probleme eingegangen : 1. interaktive Programmhandhabung 2. Nichtlinearitäten in der Berechnung durch irreversible Wandverschiebungen, teilweise vorgespannte Anker und durch adaptive Anpassung der Fußbettung 3. Behandlung von Vor- und Rückbauzuständen 4. Kopplung der Teilprogramme

Der Verbundwerkstoff Stahlfaserbeton bzw. Stahlfaserspritzbeton (SFRSpC) findet in der Geotechnik eine breite Anwendung. Für die Modellierung des mechanischen Verhaltens ist das Wissen über die Verteilung und Ausrichtung der Fasern im Beton von entscheidender Bedeutung. In einer Bachelorarbeit wurden die Stahlfasern in Bohrkernproben mit Hilfe der Computertomografie (CT) am Österreichischen Gießerei-Institut (ÖGI) sichtbar gemacht und die Orientierung jeder einzelnen Faser anhand der STL-Schnittstelle und weiterer Software berechnet, statistisch ausgewertet und grafisch, ähnlich dem Schmidt'schen Netz, dargestellt. Dieses zeitaufwändige Verfahren wurde von VRVis durch ein Postprocessing automatisiert. Die Stahlfasern können bezüglich ihrer zwei Hauptwinkel in Echtzeit exploriert, klassifiziert und dabei visuell überwacht werden. Es bieten sich verschiedene Möglichkeiten der statistischen Auswertung an. Ein Richtungs-Kugelhistogramm, ebenfalls dem Schmidt'schen Netz ähnlich, ermöglicht dem Anwender, die Richtungsverteilung der selektierten Stahlfasern auf einen Blick zu erkennen. Die Farbkodierung der Richtungen wird auch für die 3D-Visualisierung der Stahlfasern übernommen, um die räumliche Erfassung der Richtungsverteilung im SFRSpC selbst zu erleichtern.

Computertomographic Investigation of Steel Fibre Reinforced Sprayed Concrete using Multi-Dimensional Transfer Functions
The composite material steel fibre reinforced concrete or steel fibre reinforced sprayed concrete (SFRS) is widely used in geotechnics. For the modelling of the mechanical behaviour the knowledge of the distribution and orientation of the fibres in the concrete is of particular importance. For a bachelor thesis the steel fibres in drill cores were investigated by computed tomography (CT) at the Austrian Foundry Research Institute (ÖGI). The orientation of each fibre was calculated using a STL-interface and further software tools. The results were statistically evaluated and graphically represented using Schmidt's net. This time consuming (expensive) method was automated by a post-processing of VRVis. With that tool the steel fibres in the sample can be explored, classified and visually examined in real-time regarding their orientation in two angles. Different possibilities of statistical evaluation can be implemented. A real-time direction sphere histogram (DSH), comparable to Schmidt's net in 3D allows the user to recognise the distribution of orientations of the selected fibres at a glance. The colour-coding of the different orientations is also used for the 3D-volume-view of the fibres, to easily identify the spatial distribution of orientations in the SFRS sample.

Die bildanalytische Auswertung von 3-D-Computertomografieaufnahmen ermöglicht es, die Orientierung, Verteilung und Menge von Fasern in einem zu untersuchenden Betonkörper zu bestimmen.
Der folgende Bericht befasst sich mit der praktischen Anwendung dieses neuartigen Verfahrens zur Lösung typischer Fragestellungen des Bauingenieurwesens.
Die Analyse von aus Tunneltübbings entnommenen Bohrkernen zur Untersuchung des Einflusses der Herstellart auf die Orientierung und räumliche Verteilung der Fasern zeigt beispielhaft die Anwendungsmöglichkeiten des Verfahrens. Der Fokus der durchgeführten Arbeiten lag hierbei auf der Festlegung des anzusetzenden Faktors zur Berücksichtigung der Faserorientierung nach DAfStb-Richtlinie “Stahlfaserbeton”.

Computed tomography - tracking the fibres
An analytical method based on the image analysis of 3D-computed tomography makes it possible to determine orientation, distribution and quantity of fibers within the concrete specimen, which has to be examined. The following review focus on the practical application of this new method to answer typical questions within construction engineering.
The analysis of drill cores extracted from tunnel segments to examine the influence of production method on the orientation of fibers and their spatial distribution is only one example for the applicability of this method. In this case, the focus of the accomplished work was on the determination of the factor to consider the fiber orientation according to the DAfStb-guideline “Stahlfaserbeton” (steelfibre reinforced concrete).

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