DEFECTS OF INTERFLOOR JOINTS OF PRECAST CONCRETE COLUMNS IN MULTI-STOREY FRAME BUILDINGS

Interfloor joints of precast reinforced concrete columns, within multi-storey frame buildings, are elements that are responsible for the structural safety of the building as a whole, and their defects may lead to the failure of both individual structures and the whole building. Investigation of the hidden defects of the interfloor joints of columns of multi-storey industrial buildings erected in the 80s of the 20th century is an urgent task due to the fact that the existing regulatory documents do not allow to consider the peculiarities of the work of these joints with productive and assembly structural deviations of different types. These hidden
defects are common at the joints of the columns, differ from the ideal typical solutions, and not all deviations are normalized. This especially refers to change of the nature of work at the column joints of compressedbent armature, or the unilateral directional deviation of reinforcements combined with bathroom welding from the vertical axis of the columns. The search for these hidden defects becomes relevant within the reconstruction of buildings with frame. In the work some of the hidden defects recorded in the visual inspection process are considered.

An identification and an analysis of hidden defects is relevant in the reconstruction of precast concrete frames of buildings with the need of superstructure and the possibility of increasing the payload on the overlap. Fixation of hidden defects makes it possible to consider the various structural deviations of the element joints in the reconstruction of such buildings, what may be observed during the process of visual inspection. Obtained information from a fixed range of defects of various types will give direction to their limitation in the absence for some of them of tolerances to their limit values in the methods for their calculation in normative documents and recommendations for the calculation of joints.