The aim of the paper is to present the possibilities and limitations of using the Digital Image Correlation systems. In order to assess the measurement inaccuracies the measuring volume 1250 × 1100 mm was analysed using two cameras with sensor resolution 6 megapixels. It was stated very good accuracy of the line segment length change. It causes that observation of crack widths can be considered as precisely. Some practical information concern how determine the compatibility between crack width measured traditionally and by using DIC are given. In the second part of the paper the results of the tests concerning capacity of interface between two concrete casting at the same time were presented. Use of the optical measurement system Aramis enables the analysis of the deformation, determination of failure mode of the tested specimens and limit displacement between edges of the interface.

In the paper the problem of strengthening of flat slabs against punching shear was discussed. Selected methods verified on the basis of experimental tests such as increasing size of the support, applying post-installed shear reinforcement or increasing the main reinforcement by installing additional steel flat bars, were presented. The previous studies demonstrated, that the last method allows for an increase in punching shear resistance of up to 90%, depending on the longitudinal reinforcement ratio. The example of the application of such strengthening technique in the real structure was described. The use of steel flat bars located in the vicinity of the columns and additionally anchored to the slab made possible to compensate for the load capacity deficiencies that occurred due to execution errors (lowering of the main reinforcement within the support zones).