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High sophisticated full field interferometry (ESPI) on concentrate loaded concrete

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von:
Andreas Unterweger
Konrad Bergmeister
Ronald Mihala
Institute of Structural Engineering
University of Natural Resources and Applied Life Sciences
Vienna, Austria

Textauszug:

Abstract
The maximum load of shear loaded anchors close to the edge is accompanied by cracks
of huge length. The initiation of these cracks starts already at a low load level. In
contradiction to reinforced concrete in this case the load transfer is achieved by the
partial already cracked structure which cannot be neglected.

Electronic Speckle Pattern Interferometry (ESPI) is used to analyse the distribution
of strain near shear loaded expansion anchors. Superficial micro cracks can be made
visible directly after their initiation and their crack width can be quantified in the range
of micrometers. Difficulties and possibilities for a two-dimensional application are shown. Due to the low deformation, various outer influences can falsify the results. A satisfactory output only can be guaranteed with the knowledge of the behaviour of concrete surface, impact of vibration and outer light etc.

Micro cracks often don’t grow to visible macro cracks because of the big spreading of concrete tensile strength. They lead already to a relocation of stress distribution andtherefore they change the flow of forces. Consequently the localisation of invisible micro cracks is important for understanding the whole crack process.

  • Optical and finite element methods
  • Test facilities
  • General setup
  • Verifying crack width
  • Crack initiation of shear loaded fasteners close to edge
  • Summary

Dieser Fachbeitrag ist in der Ausgabe vom 02.11.2007 des VÖZfi – Kolloquium auf den Seiten 14-22  zu finden.

>>Download

(64 Seiten als Pdf_Dokument, externer Link)

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