DEFINITION OF STRESS-STRAIN STATE OF A REINFORCED CONCRETE BEAM TAKING INTO ACCOUNT THE INFLUENCE OF CYCLIC EFFECTS OF ALTERNATING TEMPERATURE

Abstract

The article presents a method for selecting a design model and the results of experimental investigation of the behavior of steel-reinforced concrete beams under static loading and cyclic exposure to fluctuating temperature, as well as an analysis of the negative impact of fluctuating temperature loads on the steel-reinforced concrete beams.

The methodology for frost resistance calculation in Ukraine is limited to testing concrete cubes, which does not consider the presence of reinforcement in the structure, as well as its quantity and location in the cross-section. With Ukraine transitioning to European design standards, this issue has become even more relevant. According to the Eurocode requirements, the amount of transverse reinforcement in the support zone increases compared to national design standards.

To develop a mathematical model for reinforced concrete, steel-reinforced concrete, and other heterogeneous structures, it is necessary to select the appropriate methodology and calculation algorithm that considers various physico-mechanical properties of materials in conjunction with other influences. For this purpose, numerical modeling software employs various techniques for constructing finite element meshes and calculation algorithms, enabling the widespread application of numerical models across different fields.

The process of thermal testing and operation of reinforced concrete elements in building structures and engineering systems is accompanied by external influences of various physical nature. However, the most significant ones from a practical point of view are non-uniform thermal actions.

The non-uniformity of the temperature field in a heterogeneous system leads to the occurrence of thermal stresses, which can cause structural failure, often accompanied by a loss of its functionality.

Modern methods for assessing the condition of concrete and reinforced concrete structures are based on a model that treats them as a monolithic homogeneous continuum with certain averaged properties [1-3]. However, such an approach to evaluating the performance of reinforced concrete structures is highly approximate and involves a number of significant simplifying assumptions.