Photogrammetric deformation measurement of concrete flat slab

Measuring of building components deformations during load tests is mostly done by the methods of length difference measurement, using instruments like dilatometers and inductive sensors. But during this measurements problems can occur related to contact measurement, measurement of only one dimension (length), limited number of sensors located on the object, need of cabling, influence of other physical environment properties (humidity, temperature) etc. These complications can be well eliminated by the non-contact optical methods. In our contribution we use various methods of digital photogrammetry for the documentation of static deformations in various load stages, specifically a combination of time baseline and multi-image convergent photogrammetry. The main goal of this measurements was the determination of deformation in the plane of the concrete surface expressed by length changes between observed points. This was possible thanks to calculating the changes of image coordinates of points using the time baseline method. Accuracy at sub-millimeter level was achieved and advantages of this measurement technique are commented.