PSI - Issue 78

Rawand Alnsour et al. / Procedia Structural Integrity 78 (2026) 1261–1268

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Fig. 7. Patterns of the anchorage of EB CFRP sheets using anchor bolts and strips (Bae & Belarbi, 2013).

3. Seismic suitability This section provides a comparative overview of different retrofitting techniques, analyzing their effectiveness under seismic conditions. The evaluation highlights the advantages and disadvantages of each method in resisting seismic forces, as detailed in Table 1.

Table 1. Summary of retrofitting methods for seismic suitability.

Technique

Advantages

Disadvantages

Improves ductility and stiffness, promotes stable energy dissipation under cyclic loading, and reduces degradation and cracking from load reversals. It also lowers the risk of brittle failure. Improves ductile behavior and ability to dissipate energy during cyclic loading, boosts stiffness and resistance to lateral forces, and helps postpone the onset of brittle failure mechanisms. Surface-applied FRP sheets enhance shear strength and prevent brittle failure, making them effective for seismic strengthening when properly applied. Offers excellent fatigue resistance, maintains bond during load reversals, improves ductility and energy dissipation, and is less prone to debonding than external FRP systems. Enhances ductility, energy absorption, seismic load capacity, and bonding strength while reducing early debonding and FRP failure.

Under cyclic loading, stress concentration around anchor zones can lead to cracking and fatigue in connectors. Poor bonding or detailing may cause slippage, stiffness degradation, or pinching in the hysteresis response. Weak bonding can cause separation under repeated loads, while poor detailing may lead to cracking or spalling. Added structural mass can also increase seismic demands. There is a risk of debonding, especially if surface preparation is inadequate, and installation can be difficult in tight or hard-to-reach locations. Groove preparation is time-consuming and requires precision; shallow grooves and weakened epoxy during heavy deformation can reduce strengthening effectiveness. Prone to combined failures like debonding and cracking, seismic effectiveness relies on precise installation. Bond quality may worsen with repeated cycles, and long-term seismic performance data is limited. Stress around anchors can cause damage and fatigue, risking premature failure or slippage under cyclic loads, which may reduce retrofit effectiveness.

Externally bonded steel plates (Shoukry et al., 2022)

Concrete jacketing (Hung et al., 2023)

EB FRP (Colalillo & Sheikh, 2012)

NSM FRP (Hashemi & Tajmir Riahi, 2022)

Hybrid techniques (Jalaeian Zaferani & Shariatmadar, 2022)

Improves seismic performance with stronger bond, delayed debonding, increased strength, ductility, and energy dissipation, maintaining FRP effectiveness after deformation.

Mechanical anchorage system (Heydari et al., 2025)