PSI - Issue 78

Teklewoin Haile Fitwi et al. / Procedia Structural Integrity 78 (2026) 1775–1782

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4.4 Normalized performance analysis

Due to significant differences in the initial material properties a performance evaluation through normalized indices was carried out in order to enable direct comparison between specimens. As shown in Fig. 6, force and energy normalization was carried out based on the joint geometry ( ,ℎ ) and concrete compressive strength ( ′ ) , through the ratio = /( ℎ √ ′ ) and = /( ℎ √ ′ ) respectively. In addition, two key parameters were adopted: Strength Index ( = / 1 ) and Energy Index ( = / 1 ), where subscript 's' denotes strengthened specimens and '1' represents the reference specimen. Considering the normalized force, carbon FRCM (Specimen 2F) achieved higher strength restoration characteristics (SI ≈ 1.4) compared to Specimen 3F with basalt FRCM (SI ≈ 1.2), Furthermore, the Energy Index comparison confirmed that carbon FRCM showed addi tionally a better energy dissipation capacity (EI ≈ 1.8) compared to basalt FRCM (EI ≈ 1.5). Both systems however showed a significant improvement compared to the control specimen, recording respectively 80% and 50% higher cumulative energy dissipation values.

Fig. 6. (a) normalized strength; (b) normalized energy dissipation.

5. Conclusions This experimental study provides evidence that both carbon and basalt Fabric Reinforced Cementitious Matrix (FRCM) systems offer an effective solution for seismic strengthening of deficient exterior beam-column joints. Carbon FRCM demonstrated superior retrofitting effectiveness with 40% increase in strength capacity and 80% increase in energy dissipation capacity compared to unstrengthened baseline specimens, while basalt FRCM showed moderate improvements with 20% increase in strength capacity and 50% increase in energy dissipation capacity relative to unstrengthened reference conditions. In addition both systems successfully transformed brittle joint shear failure mechanisms into an improved beam-joint failure mode. The experimental findings establish that FRCM systems represent a potential strengthening solution for seismically deficient exterior reinforced concrete joints in applications requiring both strength restoration or energy dissipation enhancement.