STRENGTHENING OF MONOLITHIC REINFORCED CONCRETE SLABS BY INSTALLING ADDITIONAL BEAMS THROUGH TECHNOLOGICAL OPENINGS: FROM ANALYSIS TO IMPLEMENTATION

Abstract

reconstruction, strengthening, reinforced concrete slabs, reinforced concrete beams, deflection.

The paper presents a method for strengthening monolithic reinforced concrete floor slabs in existing buildings with insufficient stiffness and excessive deflections. Based on the results of a technical inspection, typical defects such as cracking and increased deflections close to the allowable limits were identified. The analysis of the stress-strain state showed that the serviceability limit state governs the structural behavior, while the load-bearing capacity remains sufficient.

A strengthening technique based on the installation of additional reinforced concrete beams through technological openings in the slab is proposed. The method allows the formation of new load-bearing elements without dismantling the existing structure. Numerical analysis was performed using actual material properties and geometric parameters obtained from in-situ investigations.

Experimental studies were carried out on a scaled slab model with openings using the digital image correlation (DIC) method. The results confirmed the influence of openings on the deformation pattern and justified the need for stiffness compensation.

The proposed strengthening solution was successfully implemented in practice. The construction process included cutting technological openings, installing reinforcement cages, formwork arrangement, and concreting through the slab thickness. The method demonstrated its effectiveness in improving structural stiffness and ensuring serviceability without significant intervention in the existing structure.

The developed approach can be recommended for the strengthening and reconstruction of reinforced concrete slabs in buildings with similar structural deficiencies.

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