THE LOW CYCLE LOADING INTO ACCOUNT WHEN CHECKING CALCULATING THE HOLLOW-CORE SLAB SECTION ENLARGEMENT BY INCREASING THE REINFORCED CONCRETE CROSS-SECTION FROM TOP
The paper provides an example of checking calculation of hollow-core slab strengthened by section enlargement (increasing the reinforced concrete cross-section) under low-cycle loading condition. The cases when low-cycle loading negative affects the flexural capacity of reinforced concrete structures are considered. This example is analysed and designed in accordance with the provisions of Eurocode 2. The calculation is based on the use of the transformed stress-strain diagrams diagram for concrete in compression. Transformation principle for stress-strain diagram is coordinate transformations. In this case the special empirical coefficient of compressive concrete strength can be used. The coefficient is determined depending on the type of concrete and the level of loading. The proposed elastic-plastic model is based on the method of ultimate-strength relaxation. This calculation procedure allows to perform the calculation without the use of special software systems. At the same time, the use of a bi-linear stress-strain transformed relation provides sufficient accuracy of the results obtained, which is much larger in comparison with the rigid-plastic model.
