Existing design guidelines for concrete hinges consider bending-induced tensile cracking, but the structural behavior is oversimplified to be time-independent. This is the motivation to study creep and bending-induced tensile cracking of initially monolithic concrete hinges systematically. Material tests on plain concrete specimens and structural tests on marginally reinforced concrete hinges are performed. The experiments characterize material and structural creep under centric compression as well as bending-induced tensile cracking and the interaction between creep and cracking of concrete hinges. As for the latter two aims, three nominally identical concrete hinges are subjected to short-term and to longer-term eccentric compression tests. Obtained material and structural creep functions referring to centric compression are found to be very similar. The structural creep activity under eccentric compression is significantly larger because of the interaction between creep and cracking, i.e. bending-induced cracks progressively open and propagate under sustained eccentric loading. As for concrete hinges in frame-like integral bridge construction, it is concluded (i) that realistic simulation of variable loads requires consideration of the here-studied time-dependent behavior and (ii) that permanent compressive normal forces shall be limited by 45% of the ultimate load carrying capacity, in order to avoid damage of concrete hinges under sustained loading.

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This article explains the process of developing a new method, called the balanced lift method, for constructing bridges based on an alternative to the bridge construction techniques used nowadays. The most common methods of building bridges are those using falsework or the cantilever method, but a rather uncommon method, the lowering of arches is seen as the origin of the balanced lift method. The idea was to create a method that would allow a bridge to be built in a very fast manner without the need for falsework, using prefabricated elements and assembling all parts together in a position – in this case vertically – that would simplify the construction process. In order to reach the final state of the bridge, the parts assembled vertically are rotated into their final horizontal position. This article contains descriptions of the development of the method, a large‐scale test and two bridges already designed using the balanced lift method.

Der Eurocode 2 (EN 1992‐1‐1) beschäftigt sich mit der Bemessung und Konstruktion von Stahlbeton‐ und Spannbetontragwerken. Eine eingehende Betrachtung und der Vergleich der nationalen Anhänge sind notwendig, um die Unterschiede der national festgelegten Berechnungsparameter zu verifizieren. Dieser Aufsatz gibt einen Überblick über die gegenwärtige Situation und zeigt die wesentlichen Unterschiede der nationalen Anhänge der EN 1992‐1‐1 zu den Themen Querkraft und Durchstanzen auf.Shear and Punching Shear verifications in comparison to the national annexes of the Eurocode 2In order to get the Eurocodes accepted, it was necessary to allow national choices with regard to parameters where no agreement between the countries involved could be reached. For the part EN 1992‐1‐1 “Design of concrete structures – Part I: General rules and rules for buildings” altogether 121 parameters have been defined which are subject to national choices. A comparison of the national choices can show where in future easily agreement can be reached. On the other hand parameters can be identified for which significant disagreement exist, which invites to further discussions and even research. In this paper, as an experiment, the nationally defined parameters of 18 countries are compared for the chapters on shear and punching, which subjects are now, for several reasons, again in the centre of interest.

In a bridge construction process, where large concrete elements are rotated with the aid of strand lifting units (lowering of arch halves, balanced lift method), the tendons have to be deviated over saddles with small radii of curvature. Since information on the ultimate strength of curved strand tendons was not available at the time, a test programme was carried out in order to determine the ultimate strength as a function of radius of curvature (R = 0.5 m, R = 1.0 m, R = 3.0 m, straight tendons), number of strands (1 to 55) and type of strand (0.5″ and 0.6″). The results of the full scale experiments showed almost no decrease in efficiency with regard to single strand tendons and only moderate losses regarding multistrand tendons. Based on the experimental results and a biaxial failure criterion, an analytical model was developed which is able to predict the ultimate strength of curved tendons.