A method for calculating flexural multi-layer reinforced concrete structures

In construction practice, reinforced concrete structures are designed to meet the requirements of not only the load-bearing capacity but also the abilities of sound insulation, heat insulation, fire resistance, etc. A promising and effective solution to meet these requirements is using multi-layer reinforced concrete structures with an internal layer by low thermal conductivity concrete, and external layers by traditional concrete, high-strength concrete, or kezamzit concrete. The different physical-mechanical properties of the material layers affect the structure's performance under load. In this study, the authors have introduced a theoretical method to calculate and analyze the stress-strain states of flexural reinforced concrete structures with cross-sectional sections consisting of layers from different concrete materials under the effect of load. The study's results have shown that in the manufacturing process of multi-layer reinforced concrete structures by different concretes, a contact zone is formed between layers because of aggregate components from different types of concrete. Calculated results by using the proposed model have shown that the values of the moment and deflection of the beam when cracks begin to appear and when the beam is damaged, are closer to the experimental results than by using the previous models. The research results are useful references for the calculation of multi-layer reinforced concrete structures with a middle layer from lightweight concrete.