Research of energy-efficient approaches to optimization of enveloping and bearing structures, taking into account thermomechanical interaction of materials

Abstract

The scientific article explores energy-efficient strategies for optimization of enveloping and bearing structures of buildings through comprehensive consideration of thermomechanical interaction of materials, characterized by mutual influence of temperature fields and mechanical stresses in multilayer systems. Traditional methods of separate analysis of thermal and strength indicators demonstrate limitations in assessing the real behavior of structures, where temperature gradients induce stress fields, and mechanical loads modify the structure of thermal insulation materials, changing their thermal conductivity. Comprehensive numerical modeling using coupled models in finite element software packages, combined with experimental data from 47 construction sites in harsh climatic conditions, revealed discrepancies between calculated and measured values of thermal resistance of up to 35%, with the contribution of linear and point thermal bridges to the total losses through the building envelope ranging from 18% to 42%. In the areas of fastening of curtain facades, with a temperature difference of 60° C, cyclic compressive and tensile stresses of up to 47 and 38 MPa, respectively, occur, leading to the risk of fatigue failure. A nonlinear dependence of thermal conductivity on compressive stresses has been established for insulation materials: low-density fibrous materials show a 20% increase in coefficient due to compaction of the structure and increased contact heat transfer, while cellular polymer and aerogel materials remain stable, with correlations between density and thermal conductivity changes described by power functions with indicators 1.87 and 0.64. Multi-criteria optimization, taking into account thermal protection, stress state, material consumption and life cycle economics, demonstrates the superiority of integrated solutions that reduce the material consumption of load-bearing elements by 16,2%, increase thermal protection characteristics by 45,4% and reduce energy consumption for heating with a payback of 6,8 years compared to the basic options. An analysis of the degradation of thermal properties over a 50-year period of operation revealed differentiated rates of decrease in thermal resistance, ranging from 0,199%/year for systems with PIR boards in ventilated facades to 0,481%/year for plaster systems with mineral wool, due to differences in resistance to moisture and cyclic stress. The integral results confirm the potential to reduce the reduced energy consumption by 25-32% and increase the durability of structures with the systematic application of integrated thermomechanical models, which highlights the need to improve regulatory approaches, implement three-dimensional modeling of critical nodes, and develop digital twins for monitoring and predicting the behavior of buildings throughout their entire life cycle in the context of global requirements for energy efficiency and sustainable development of the construction industry.