THE SPECIFICS OF THE CALCULATION OF FLOOR SLABS WHEN REINFORCING THEM BY INCREASING THE COMPRESSED ZONE

The article addresses the development of an advanced method for reinforcing damaged floor slabs in multi-story panel buildings, primarily focusing on those affected by explosive impacts during military conflicts. Such damages include a loss of up to 50% of the load-bearing capacity, visible cracks up to 2 mm wide in the tension zone, and excessive deflections beyond normative limits. The proposed reinforcement method involves the addition of a monolithic concrete layer to the compressed zone of the existing slab, achieved using chemical anchors to ensure composite action. Numerical modeling in "LIRA-SAPR" demonstrates that the restored slabs meet the required structural performance standards. The article comprehensively reviews existing reinforcement techniques, including the use of steel or concrete beams, fiber-reinforced polymer (FRP) overlays, and pre-stressing methods, and evaluates their applicability to panel buildings. The limitations of these methods in height-constrained apartments and the challenges of implementing internal steel reinforcements are discussed. The authors propose a novel solution tailored to the unique characteristics of panel buildings, emphasizing the compatibility of the reinforced slab and the existing structure. Key aspects of the study include determining the optimal thickness and reinforcement layout of the additional slab and designing the anchor connections for effective stress transfer. The practical implementation of the proposed method is illustrated through a case study of a heavily damaged residential building in Kharkiv, which suffered significant structural failures due to missile impacts. The analysis incorporates finite element modeling, material property assessments, and compliance with Ukrainian construction norms. Results indicate that the maximum deflection of the reinforced slab is significantly reduced to 1.48 cm, well below the allowable limit of 2.95 cm, ensuring both safety and serviceability. The proposed method offers a cost-effective and technically feasible solution for the rehabilitation of damaged residential infrastructure, facilitating the restoration of structural integrity and extending the service life of panel buildings.