PSI - Issue 78

Ahmed Mabrouk et al. / Procedia Structural Integrity 78 (2026) 960–967

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Fig. 3. a) RC frame building configuration b) acceleration response spectra of the selected records and EC8 reference spectrum

4.2. Definition of performance levels Performance levels (PL) are defined separately for infill panels and RC frame elements to allow comprehensive evaluation of structural and nonstructural behavior during dynamic loading. Infill panels are assessed using three combined IP drift – OOP displacement domains derived from experimental calibration: infDLS – Damage Limit State (first cracking or peak strength), infULS – Ultimate LS (in the range between 20% strength degradation (lower limit, ) and the theoretical point of zero resistance in the degrading branch (upper limit, ). These domains define thresholds for infill performance as a function of combined deformation, acknowledging that different combinations of IP and OOP demand can trigger failure. The domain boundaries, summarized in Table 1, are used in dynamic analysis to evaluate infill performance in real-time and identify limit exceedance. RC frame performance is assessed through standard deformation- and force-based criteria. Two global performance levels are defined frDLS – Damage Limit State: first column yielding (colYM) or 0.5% interstorey drift, frULS – Ultimate Limit State: any of the following: Exceedance of ultimate curvature (colUM, beamUM), Shear failure (colSF, beamSF), Nodal failure (NF) due to excessive plastic rotation. To evaluate these, a moment – curvature (M – χ) analysis is performed for key beam and column sections under varying axial loads. The resulting yield and ultimate curvatures are expressed as polynomial functions of axial load, which are monitored during the TH analysis. Shear and chord rotation checks follow Sezen & Moehle (2004) and Circ. 7/2019, respectively. This performance-based framework supports detailed evaluation of both structural and nonstructural components throughout the seismic analysis. 4.3. Time-History analysis, and post-processing The seismic performance of the three frame configurations — bare (BF), URM-infilled, and F-infilled — is evaluated through nonlinear TH analysis in OpenSees, using a custom STKO implementation. Each frame is subjected to seven natural ground motions, scaled to five PGA levels from 0.1g to 0.5g. The calibrated macro-model includes a displacement-based removal mechanism, which tracks the combined IP drift and OOP displacement of each infill panel. When the deformation state exceeds the inf limit, the associated strut elements are removed, simulating collapse. This process is automated via a TCL control script integrated into the dynamic analysis loop. At each step, the following performance checks are conducted, Infill panels: Evaluation against inf , inf , and inf domains, RC frame elements: curvature checks (based on limits defined from moment-curvature analysis defined a prior), shear checks using the Sezen & Moehle (2004) model, chord rotation checks based on Circ. 7/2019; global interstorey drift checks at 0.5% (DLS) and 2.0% (ULS), per EC8 and DM 2018. All checks are embedded in the time integration routine, allowing step-by-step tracking of damage evolution. After analysis, results are automatically extracted and organized by PGA level and ground motion. Outputs include maximum drifts, force – displacement