This paper explores the possibility of the partial replacement of the longitudinal reinforcement in reinforced concrete (RC) beams with recycled steel fibres (RSF). Testing was focused on the contribution of two volume ratios of the RSF—0.5%, 1.0%. Basic compression and flexural tensile tests were performed to evaluate the effectiveness of the fibres following current standards. Additionally, the full-scale beams with and without conventional reinforcement were subjected to four-point bending tests. The results indicate that RSF improved the load-bearing capacity of the RC beams. Cooperation of RSF with the steel bars in carrying loads was proved. Findings from the Digital Image Correlation (DIC) revealed no impact on the cracking pattern of the RC beams.

The paper is devoted to the influence of mining origin discontinuous deformations of on buildings. In the first part the forms of deformations, their classification, examples and reasons of their formation is discussed. It is supplemented with other classification (cited from literature) related to risk for buildings with regard to the type and intensity of deformation. In the next part, examples of damages of three various buildings located in zones of faults and sinkholes. They were: simple detached house, multi-storey and hall buildings. All of them were the subject of expertizes prepared by the authors. The type of influences and the nature of damages are illustrated with photographs and discussed. In the last part the threats due to the nature of the buildings – their height and size – are discussed. The influence of the location of deformation edge (fault, sinkhole, terrain step) in relation to the object is shortly analyzed. Examples of normal stress distribution in subsoil obtained in numerical calculations have been briefly presented. Some attention have been also paid on protection methods and their effectiveness.