Results of examination and analysis of cracks formation in a composite slab floor in an industrial warehouse hall is presented in the paper. During exploitation of the floor, on which lift trucks and presses worked, a lot of deep cracks occurred in the slab. In order to define characteristics of cracks and properties of concrete there were made different NDT examinations. Measurements of vibrations due to work of presses were also realized with aim to evaluate their possible influence on cracks formation. Static, dynamic and strength structural calculations were also made based on the model of continuous, multi-bay plate. They showed that applied slab reinforcement was sufficient and acting loads did not have to cause cracks. After 3D modelling of the building and taking into consideration the flexibility of main steel beams it was gained that in the RC floor slab over supports bending moments could occur nearly three times greater than calculated from the 2D model. Taking into consideration wrong structural model of the building led to over-loading of the floor slab, its cracking and caused a necessity of its strengthening.

Currently, new housing in city centers is more and more often developed on small plots of land, or existing buildings on such plots are rebuilt to such an extent that only their façade walls remain. In both cases, as a rule, a deep excavation is also made, either at the existing object or within its area. Serious damage often occurs because of the carried out work. It is not possible to accurately determine the response of a building to the deformation associated with the excavation due to the variability of many factors that influence it. As a result, the response of the building must be estimated on the basis of constant monitoring and approximate calculations. Depending on the size of the predicted ground displacements and the technical condition of buildings, it is often necessary to protect or strengthen their structural elements. In the paper, the authors analyzed various risk factors for the implementation of infill buildings and the revitalization of historic buildings using only their façade walls. In addition, examples of contemporary solutions for securing the walls of existing buildings, and the method of monitoring vertical deformations using the Hydrostatic Levelling Cell (HLC) system, are presented.

Industrial buildings from the beginning of the 20th century can still be found in Polish cities. Some of them have already been listed as heritage objects. Those structures where new technical solutions and materials were used, for example concrete, are especially interesting. Some of those objects are currently under a process of restoration with the aim to reconstruct and adapt them for completely new and different utility functions but without losing their important heritage value. In this paper, elements of the assessment procedure of the technical state regarding a historical survey, material examination and structural analysis, are presented on the example of two selected industrial buildings in which reinforced concrete was used as the main structural material. The main aim of the performed diagnostic procedure was verification of the load-bearing capacity of structures of the examined buildings. The calculation made confirmed that in case of not damaged concrete elements they have enough capacity to carry on newly designed loads. That confirmed that old concrete structures, especially in industrial buildings, sometimes have capacity reserves. On the other hand it allows to perform the design of less invasive renovation works or strengthening solutions with the aim to respect their industrial heritage value.