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ry cracks.
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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004
between support and bearing (figure 17). The first crack width
starts with about 0.02 mm, and ends a short time before failure
with about 0.20 mm.
5.3 Plate Tests
More complex to assess and, to this, more difficult to estimate
are plates, which are loaded biaxial by tensile or compressive
force from one or two sides.
The measurement area with 30 x 30 cm? was prepared with 59 x
59 targets (figure 18). Figure 19 shows the evolution of the
crack pattern.
Figure 19: Crack pattern of a plate test in selected epochs
The method is robust against missing targets. Figure 19 shows a
measurement display with blank areas. There the concrete was
too defective to fix all targets. It is possible to interpolate the
missing targets without a strong smearing of the crack
Structures (figure 20).
Figure 20: Interpolated targets
6. CONCLUSIONS
The paper describes several applications of digital
photogrammetry for monitoring cracks at concrete elements
during research experiments. The specimens are prepared with
circular targets and photographed with up to three digital
cameras simultaneously. The cracks are causing a variation in
the distance between adjacent targets, which is measured
photogrammetrically. Thus the evolution of the cracks can be
observed as soon as the width of the cracks exceed at least 5 —
10 um. The above-mentioned examples show, that digital
photogrammetry as non-contact measurement technique is
useful in research projects of civil engineering.
7. LITERATURE
Benning, W.; Schwermann, R., 1997: PHIDIAS-MS —
Eine digitale Photogrammetrieapplikation unter Mic-
roStation für Nahbereichsanwendungen. Allgemeine
Vermessungsnachrichten AVN, Heft |
Benning, W.; Gortz, S.; Lange, J.; Schwermann, R.;
Chudoba, R., 2003: An algorithm for automatic
analysis of deformation of reinforced concrete
structures using photogrammetry. Proceeding
Symposium NDT-CE 2003 Berlin
Chudoba, R.; Konrad, M., 2003: Dynamic Algorithmic
Components for the Development of the Finite
Element Software, CTU Reports, special edition:
Contributions to Computational and Experimental In-
vestigation of Engineering Materials and Structures,
edited by Zdenek Bittnar, Prague
Górtz, S.; Hegger, J., 2002: Schádigungsanalyse von
Stahlbetontragwerken unter Einsatz der Laser-Inter-
ferometrie und der Photogrammetrie. In: T. Luhmann
(Hrsg.) ,Photogrammetrie und Laserscanning, An-
wendungen für As-Built-Dokumentation und Facility
Management“ Wichmann Verlag pp. 172-183
Górtz, S., 2004: Zum Schubrissverhalten von profilierten
Stahlbeton- und Spannbetonbalken aus Normal- und
aus Hochleistungsbeton. Eingereichte Dissertation am
Institut für Massivbau der RWTH Aachen
Lange, 1. Benning, W., Schwermamn, R. 2004:
Photogrammetrische | Deformationsmessung | zur
Rissanalyse bei Betonbauteilen. In: T. Luhmann
(Hrsg.) ,,Photogrammetrie — Laserscanner — Optische
3D Messtechnik, Beitráge der Oldenburger 3D-
Tage* Wichmann Verlag, pp. 287-294
Wahl, F.M., 1979: Digital Image Signal Processing.
Artech Publishing
