Concrete hinge

Concrete hinges are hinges produced out of concrete, with no or almost no steel in the hinge neck, which allows a rotation without a relevant bending moment.[1] This high rotations[2][3] are resulting from controlled tensile cracks as well as creep.[4][3][1] Concrete hinges are mostly used in bridge engineering[1] as monolithic, simple, economic alternative to steel hinges, which would need regular maintenance. Concrete hinges are also used in tunnel engineering.[1][3] A concrete hinge consist of the hinge neck, which has a reduced cross section and of the hinge heads, which have a strong reinforcement.[3][1][5]

concrete hinge
concrete hinge with front side notches

History and guidelines

Freyssinet[6][7] invented the concrete hinges.[1][3] Leonhardt introduced guidelines in the 1960s which are still used till the 2010s.[1][3] Janßen introduced the application of concrete hinges in tunnel engineering.[8][3] Gladwell developed another guideline for narrowing cross sections, which predicts a stiffer behaviour than the Leonhardt/Janßen-model[3] Marx and Schacht translated Leonhardts guidelines for the first time in the nowadays used semipropablistic safteyconcept. Schlappal,[3] Kalliauer[1] and coworkers introduced for the first time both limit caces (service-limit-states (SLS) and ultimate-limite-states (ULS)). Kaufmann, Markić und Bimschas did further studies on concrete hinges.[9]

Stresses, rotational capacity, bearing capacity
normal stesses in loading direction
normal stresses in thickness direction
normal stresses in side direction

Due to triaxial compression, strength in the neck region is much higher than for uniaxial compression,[4] because lateral expansion is restricted.[1] Eurocode 2 suggests for typical dimensions a compressive strength equal to about twice of the unixalial compressive strength.[1] Also the concrete hinge neck has no, or almost no reinforcement,[1] but the concrete hinge heads need a dense reinforcement cache, because of the tensile splitting.[10][9]

Literature
  • Fritz Leonhardt: Vorlesungen über Massivbau - Teil 2 Sonderfälle der Bemessung im Stahlbetonbau. [Concrete hinges: test report, recommendations for structural design. Critical stress states of concrete under multiaxial static short-term loading Springer-Verlag, Berlin 1986, ISBN 3-540-16746-3, S. 123–132. (in German)
  • VPI: Der Prüfingenieur. Ausgabe April 2010, S. 15–26, (bvpi.de PDF; 2,3 MB). (in German)
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References
  1. Johannes Kalliauer; Thomas Schlappal; Markus Vill; Herbert Mang; Bernhard Pichler (2018-02-01). "Bearing capacity of concrete hinges subjected to eccentric compression: multiscale structural analysis of experiments". Acta Mechanica. 229 (2): 849–866. doi:10.1007/s00707-017-2004-3. ISSN 1619-6937.
  2. Schlappal et al. did experiments till above 50mrad (Fig11).
  3. Thomas Schlappal; Michael Schweigler; Susanne Gmainer; Martin Peyerl; Bernhard Pichler (2017), "Creep and cracking of concrete hinges: insight from centric and eccentric compression experiments", Materials and Structures, Springer, vol. 50, no. 6, p. 244, doi:10.1617/s11527-017-1112-9, PMC 5700241, PMID 29213209
  4. Johannes Kalliauer; Thomas Schlappal; Herbert A. Mang; Bernhard Pichler (2018). "Parameter identification as the basis for Finite Element simulations of Ultimate Limit States of concrete hinges". In Günther Meschke; Bernhard Pichler; Jan G. Rots (eds.). Computational Modelling of Concrete Structures: Proceedings of the Conference on Computational Modelling of Concrete and Concrete Structures (EURO-C 2018), February 26 – March 1, 2018, Bad Hofgastein, Austria. CRC Press. p. 689. Retrieved 2018-03-06.
  5. Fritz Leonhardt; Horst Reimann (1965), Betongelenke: Versuchsbericht; Vorschläge zur Bemessung und konstruktiven Ausbildung. Kritische Spannungszustände des Betons bei mehrachsiger, ruhender Kurzzeitbelastung (in German), Ernst
  6. Eugène Freyssinet (1923), "Le pont de Candelier (The bridge of Candelier)", Ann Ponts Chaussées (in French), vol. 1, pp. 165f
  7. Eugène Freyssinet (1954), "Naissance du béton précontraint et vues d'avenir.", Travaux, Juni (in French), pp. 463–474
  8. Pieter Janßen (1983), Tragverhalten von Tunnelausbauten mit Gelenktübbings (in German), Dissertation, Technische Universität Braunschweig
  9. Walter Kaufmann; Tomislav Markić; Martin Bimschas (February 2017), Betongelenke - Stand der Technik und Entwicklungspotential (PDF) (in German), Institut für Baustatik und Konstruktion, ETH Zürich
  10. Johannes Kalliauer (2016-04-29), Insight into the structural behavior of concrete hinges by means of Finite Element simulations, Wien: TU Wien - Vienna University of Technology
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