Introduction. A nonlinear numerical analysis of a monolithic ribbed multi-span floor slab was performed to assess the influence of corrosion damage to reinforcement and concrete on the stress-strain state. Corrosion damage to the reinforcement was taken as a 25 % loss of the bar cross-section along 70 % of the beam length. Damaged concrete was assumed to have a strength class of B5.

Materials and methods. Finite element models of full-scale tests were developed and their verification numerical calculations were performed. A finite element model of a fragment of the ribbed floor slab using solid finite elements was developed for stress-strain state analysis. The laws of nonlinear deformation for concrete and reinforcement were taken into account.

Results. Tensile stresses in the reinforcement bars were obtained for both the corrosion-damaged and undamaged models. Based on these results, graphical dependencies illustrating the redistribution of forces in the monolithic beams were plotted. A comparative analysis of deflections and the size of the compressed zone of the slab in the damaged and undamaged numerical models was performed.

Conclusions. The qualitative influence on the redistribution of forces in monolithic corrosion-damaged and undamaged beams was determined based on the criterion of plastic hinge formation. An increase in deflection and the size of the slab’s compressed zone by 23 % was identified in the damaged models.