Reconstruction and strengthening of reinforced concrete elements after fire exposure

Abstract

Fire exposure of reinforced concrete elements produces non-uniform damage to concrete and reinforcement across the member depth and length; therefore, original design material properties cannot be used without verification, and reconstruction decisions must rely on inspection data and structural checks. The objective of this paper is to present a reproducible framework for residual load-bearing assessment and to classify post-fire repair and strengthening solutions with regard to composite action and anchorage limitations. The method follows the code-based sequence: collecting background information, recording defects, zoning elements by heating intensity, assigning residual properties to concrete and reinforcement, and performing a verification analysis for each member to select an intervention strategy – repair, strengthening, or replacement. The results summarize and compare major strengthening approaches, including externally bonded carbon-fibre composites, reinforced concrete jackets and confinement systems, and the use of polypropylene fibres in repair layers, as well as experimental-computational procedures using controllable standard fire-temperature regimes. The study highlights that bond quality and the performance of cold anchorage zones under heating govern structural reliability; for polymer-composite strengthening, the adhesive layer and the effectiveness of fire insulation become decisive.