PSI - Issue 78

Marco Terrenzi et al. / Procedia Structural Integrity 78 (2026) 418–425

420

Fig. 1: Structural layout of six-story case study building

within beam / column elements or at beam-column joints. The infills were modeled using compression-only diagonal strut elements, following the phenomenological model by (Decanini and Fantin, 1987), updated by Cardone and Perrone (2015) and Sassun et al. (2016). This model captures the monotonic and cyclic behavior of infills based on their mechanical and geometric characteristics, notably incor porating the influence of openings(Decanini et al., 2014). The material behavior was defined using Concrete01 (Noh et al., 2017). Modal analysis was conducted on both the BF and IF models. This analysis followed the application of gravity loads, specifically the seismic load combination of 100% dead load plus 30% live load. The results for both models are presented in Table 1.

Table 1: Modal characteristics after application of the gravity loads for BF and IF building

Mode 1

Mode 2

Mode 3

Mode 4

Mode 5

Mode 6

Mode 7

T 1 = 2.60[s] M n , y = 78.65% T 1 = 0.97[s] M n , y = 93.56%

T 2 = 1.48[s]

T 3 = 1.21[s]

T 4 = 0.78[s] M n , y = 10.97% T 4 = 0.30[s] M n , y = 5.41%

T 5 = 0.47[s]

T 6 = 0.41[s] M n , y = 5.00%

T 7 = 0.40[s]

BF

M n , rot = 80.45%

M n , x = 79.34%

M n , rot = 10.49%

M n , x = 11.02% T 7 = 0.16[s] M n , y = 0.66%

T 2 = 0.64[s]

T 3 = 0.53[s]

T 5 = 0.21[s] M n , x = 8.90%

T 6 = 0.17[s]

IF

M n , x = 70.21%

M n , rot = 74.51%

M n , rot = 4.82%

3. Nonlinear Time-History Analyses

Ground motion records for Nonlinear Time-History Analyses (NTHAs) were selected from the European Strong motion (ESD) Ambraseys et al. (2004) and Engineering Strong-Motion (ESM) Lanzano et al. (2019) databases. Crite ria included Mw 6.5, epicentral distance 50 km, and soil category A. A total of 45 unscaled ground motions (26 from ESD and 19 from ESM) were used, considering only their two orthogonal horizontal components. Initially, the NTHAs were conducted considering only hysteretic damping, without additional viscous damping. The engineering demand parameters (EDPs) (Terrenzi et al., 2018, 2022) selected for evaluation were the maximum ab solute roof displacements (RD) of the top floor diaphragm master node, recorded in both the X and Y directions. Due to convergence failures encountered in the analyses of four ground motions for both the BF and IF buildings, the re sults from these specific analyses were excluded. This decision was made to maintain the integrity of the comparison betweendi ff erent damping approaches, which is the primary objective of this work.