Concrete hinge
Concrete hinges are hinges produced out of concrete, with little or no steel in the hinge neck, which allows a rotation without a significant bending moment.[1] The high rotations[2][3] result 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]
History and guidelines
[edit | edit source]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
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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 tensile splitting.[10][9]
Literature
[edit | edit source]- 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, Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value)., S. 123–132. (in German)
- VPI: Der Prüfingenieur. Ausgabe April 2010, S. 15–26, (bvpi.de PDF; 2,3 MB). (in German)
References
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- ^ Schlappal et al. did experiments till above 50mrad (Fig11).
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