The article presents proposals for the calculation of three-layer reinforced concrete slab structures, the outer layers of which are made of heavy concrete, the middle layer is made of lightweight expanded clay concrete. Experimental elements were calculated according to the compiled program of iterative calculation, which takes into account the concrete deformation diagram in an explicit form. The calculation program reflects a technique that allows you to determine the actual distribution of deformations in sections with a crack and in the areas between them. The results of the calculation of the prototypes indicate a close convergence of the theoretical values ​​of the breaking moments, deflections, deformations of the extreme fibers, and cracking forces with those directly recorded in experimental studies.

Keywords: concrete, reinforced concrete, expanded clay concrete, reinforcement, three-layer slab, prestressing, calculation methods, deformations, stresses, deflections