Issue 78

S. A. Mustafa et alii, Fracture and Structural Integrity, 78 (2026) 298-314; DOI: 10.3221/IGF-ESIS.78.18

Figure 16: Cumulative energy dissipation versus drift ratio for the tested shear wall specimens under cyclic loading. Stiffness degradation characteristics As shown, stiffness degradation with increasing displacement amplitude was found for all specimens which is a common phenomenon of RC shear walls under cyclic loading. The degradation rate, however, differed widely. The control wall had the highest secant stiffness during the entire test, which indicates good anchorage and effective load transfer. The stiffness of S.W.I 1 sharply dropped after its first crack, indicating that interface slip was dominating its response. In contrast, much higher level of stiffness remained over a larger number of cycles in case of S.W.I 2 and S.W.I 3. This indicates that with larger embedment lengths anchorage degradation happens after a longer time and enables the wall to resist lateral loads. Drift capacity and ductility considerations While all specimens had differing levels of strength, the ultimate drift capacities were consistent between specimens from 2.4% to 2.8%. This means that even walls with relatively low levels of anchorage could sustain large lateral deformations before experiencing a loss of 20% of maximum strength. This large deformation was achieved in different manners. While S.W.I 1 was able to achieve relatively large ultimate displacements, much of this deformation was tied to interface slip rather than distributed plasticity across the wall. This type of deformation would be unfavorable from a seismic performance point of view due to limited energy dissipation and possible loss of load path integrity. S.W.I 3 achieved the best combination of strength, stable hysteretic behavior, and relatively ductile behavior among the implanted specimens. It should be noted that the interpretation of the deformation mechanism was based on the measured global top displacement together with observed crack development and interface behavior. his research investigated the performance of newly added reinforced concrete shear walls anchored to existing foundations using post-installed vertical reinforcement. The experimental program included two stages; pull-out tests to obtain the best bonding material to be used and the size of the hole at which the implanted bars will be inserted. The second stage involved testing four large-scale shear walls under cyclic load. The study evaluated the influence of anchorage parameters on global strength, stiffness, ductility, and failure mechanisms. The main findings obtained from the experimental investigation are summarized below:  The pull-out tests demonstrated that anchorage performance is significantly influenced by both adhesive type and hole diameter. Among the investigated configurations, the combination of CMB adhesive and a hole diameter of 1.25Ø provided the most reliable performance, exhibiting high pull-out capacity and predominantly concrete cone failure, indicating efficient force transfer between the reinforcement and the surrounding concrete.  The embedment length of post-installed reinforcement was found to be a critical parameter affecting the lateral load capacity of shear walls under cyclic loading. The specimens with embedment lengths of 10Ø, 15Ø, and 20Ø achieved approximately 26%, 44%, and 63%, respectively, of the peak lateral strength of the control wall, demonstrating the substantial influence of anchorage length on global structural performance.  The observed failure modes revealed a clear transition from anchorage-controlled behavior to section-controlled behavior as embedment length increased. Short embedment lengths resulted in premature interface opening and T C ONCLUSIONS

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