CHANGE OF NORMAL CRACK WIDTH INTHE REINFORCED-CONCRETE BENDING ELEMENTS UNDER THE ACTION OF ALTERNATING LOW-CYCLE LOADINGS

Abstract

One of the main tasks of the reinforced concrete structures calculation is to limit the cracks width in order to ensure corrosion resistance of the reinforcement, protect the reinforcement from extreme heat during fires, withstand aesthetic requirements and ensure the overall integrity of the structure. In order to guarantee the reliability of reinforced concrete structures it is necessary to know the patterns of changes in structures load-bearing capacity and deformability of materials under the action not only one-time static load, as provided in current regulations, but also in other loading modes.

The article is devoted to the results of experimental researches of the fracture strength of reinforced-concrete bending elements under the action of the alternating low-cycle loadings. During operation a large number of reinforced concrete structures are exposed to low-cycle repeated and alternating loads, which may occur within the operating level or exceed it. Such loads include wind, process, seismic, temperature and humidity and others. Alternating loads and deformations occur in continuous beams, edge columnsof industrial buildings, silos and prestressed structures and so on.Improved calculation method of the opening widths of normal crack under the action of the noted loadings was offered. The proposed calculation method gives a satisfactory agreement with the experimental data.