PSI - Issue 84

Emeka John Ude et al. / Procedia Structural Integrity 84 (2026) 1294–1301

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formulation entails defining a bond slip evolution for the concrete-steel interface and was implemented for all levels of corrosion (10 - 50%). The final implementation was possible in the STKO software using the ASDEmbededRebarWithSlip constraint command. 4. Results 4.1. Model Validation The load curve of the reference beam is shown in Fig. 5. While the numerical load curve is seen to be stiffer elastic branch, the experimental load cure, the peak load and softening branch for both curves are however very similar. In particular, the peak load from the numerical result is 531 kN occurring at a displacement of 25 mm while that of the experiment was 537 kN occurring at displacement at 21 mm which represents a 1.1% deviation from the experimental result. Also comparing the overall damage and especially the crack patterns between the experimental and numerical results (Fig. 6.), there is a similar replication of the crack initiation at the re-entrant point with a diagonal propagation - signifying a shear failure pattern. The crack path (Fig. 6b) is realized by visualizing the represented by the maximum principal strain.

Fig. 5. Load curve of FEM validation

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(b)

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Fig. 6. Comparing results at end of loading (a) concrete damage (b) numerical crack pattern (b) experimental crack patterns

In the case of the strengthened pre-damaged beam, the Fig. 7 show the load curve for the different retrofit configurations. The numerical model results is observed to align with the experimental result in terms of the maximum load of the strengthened beams. The details of the capacities of the strengthened and un-strengthened beams are summarized in Table 3 . It can be concluded from the load curves (original beam and retrofitted beam) that the calibration of the experimental campaign is acceptable as the highest deviation between numerical and experimental results in terms of the load capacities is +2.6% ( Table 3 ). This gives the confidence to utilize this model for further investigations and analyses not considered in the experimental campaign. 4.2. Improvement of FRCM strengthening The experimental campaign reflects a very low improvement of the beam capacity; therefore, this study proposed an improved retrofit approach. The proposed improvement entails reduction of the fiber spacing of the FRCM as well