Numerical Analysis of the Thermo-Stressed State of Reinforced Concrete Bridge Beams Strengthened with Polymer Concrete Based on Methyl Methacrylate Compositions

Abstract

Purpose. To establish the patterns of temperature field distribution and thermal stresses in strengthened defective reinforced concrete bridge beams reinforced with polymer concrete based on methyl methacrylate compositions using permanent metal formwork under the influence of ambient temperatures. Methodology. The finite element method was used to determine the patterns of changes in the stress-strain state of reinforced concrete bridge beams strengthened with polymer concrete based on methyl methacrylate compositions using permanent metal formwork. For this purpose, a geometric and finite element model of the structural strengthening of a reinforced concrete bridge beam was developed, taking into account the physical and mechanical properties of the strengthening materials and the boundary conditions. The calculation of temperature fields and thermal stresses was carried out considering the effects of positive and negative ambient temperatures, as well as alternating temperature conditions. Findings. As a result of the conducted study, the distribution of temperature fields and thermal stresses in the strengthened reinforced concrete bridge beam was obtained. Based on the obtained dependences of the temperature gradient at the interfaces of the structural materials of the strengthened beam under temperature influence, it was established that a temperature gradient exists in the cross-section of the strengthened beam at the interface between the permanent metal formwork and the bonding mass of methyl methacrylate strengthening. The results of calculating thermal stresses and deformations in the strengthened bridge beam showed that the maximum value of thermal stresses under positive temperatures applied to the surface of the permanent metal formwork and the reinforced concrete bridge beam reached 15.54 MPa. Under negative temperatures, the thermal stresses reached 135.0 MPa, while under alternating temperature conditions on the surfaces of the strengthened beam, the maximum thermal stresses amounted to 8.98 MPa. The obtained isofields of thermal stress distribution made it possible to determine that the maximum stresses occur at the interface between the permanent metal formwork and the polymer concrete based on methyl methacrylate compositions. Originality. The finite element method for assessing the thermal stress state of strengthened reinforced concrete bridge beams was further developed, which made it possible to establish the patterns of changes in the thermal stress state of reinforced concrete bridge beams strengthened with polymer concrete based on methyl methacrylate compositions using permanent metal formwork while considering the influence of ambient temperatures. Practical value. The establishment and investigation of the patterns of the thermal stress state of strengthened reinforced concrete bridge beams will make it possible to assess the influence of temperature on the stress-strain state of reinforced concrete bridge beams strengthened with polymer concrete based on methyl methacrylate compositions using permanent metal formwork. This can be taken into account at the design stage of such repair methods for defective reinforced concrete bridge beams by selecting the characteristics of structural materials for specific environmental conditions.