PSI - Issue 78

Giada Frappa et al. / Procedia Structural Integrity 78 (2026) 89–97

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Fig. 3. Geometry, dimensions and reinforcement detailing of specimens investigated by Melo et al. (2001).

All specimens (Fig. 3) were constructed without transverse reinforcement in the joint core and shared identical geometric configurations. Specimens TPA-1 and TPA-2 served as control units, incorporating beam longitudinal reinforcement anchored with 90-degree hooks. Specimens TPB-1 and TPB-2 differed from the control units in that the column longitudinal bars were lap-spliced, while specimen TPC used 180-degree hooks for the beam reinforcement. Specimen TD was identical in geometry and detailing to TPA but utilized deformed bars instead of plain bars. All specimens were tested under a column axial load corresponding to approximately 13% of the column ’ s axial load capacity. To evaluate the effects of loading protocol, specimens TPA-1 and TPB-1 were tested under monotonic loading, while the remaining specimens were subjected to cyclic loading. Test results demonstrated that the bond characteristics of the reinforcement significantly influenced the seismic performance of the joints. Specimens reinforced with plain bars exhibited lower energy dissipation capacity, stiffness, and equivalent damping compared to the specimen with deformed bars. Among the plain bar specimens, those with lap-splicing in the columns (TPB-1 and TPB-2) dissipated more energy than the control specimens (TPA-1 and TPA-2), with damage localized at the column – joint interface and no significant cracking observed in the joint core (Fig. 4). In contrast, all other specimens, including TPA, TPC, and TD, developed diagonal shear cracks within the joint core.