PSI - Issue 44

Domenico Magisano et al. / Procedia Structural Integrity 44 (2023) 456–463 Magisano et al. / Structural Integrity Procedia 00 (2022) 000–000

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460

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w 2

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Fig. 4: Mildly irregular frame: collapse mechanisms associated to linear mode shapes in XZ plane.

story 1 collapse mechanism story 2 collapse mechanism story 3 collapse mechanism story 4 collapse mechanism story 5 collapse mechanism

Fig. 5: Mildly irregular frame: story mechanisms in XZ plane.

5.1. Sensitivity to the seismic direction

The first test examines the direction of the seismic action in the horizontal plane. Three di ff erent tests are carried out, with direction 0°, 45°, 90° of the seismic action respectively. Fig. 6 depicts the comparison of displacement time history and profile deformation between FULL model and ROM for 0°, 45°, 90° directions. 5.1.1. Sensitivity to the scale factor of seismic action The accuracy of the ROM is now tested with respect to scale factors of seismic action. The control node is the same considered in the previous test as well as the ROM dimension. In Fig.7, the time history and maximum profile deformation for FULL model and ROM are compared for scale factors 0.25, 1 and 4. Finally, the distribution of the story shear forces along the seismic direction is reported in Fig. 8 for the di ff erent scale factors. We can note a good agreement with the full model solution. 5.1.2. Sensitivity to the random frequency content In Tab. 2, the peak displacement values of the control node are reported for both FULL model and ROM, together with the corresponding percentage error, for a set of ten di ff erent analyses with an equal number of spectrum compat ible ground motion records which di ff er for the random frequency content. A seismic direction of 0°and S F = 1 are considered. We can note a very low mean value of the error, while the maximum error is about 7%. Similar conclusions can be drawn for the maximum shear story force as reported in Tab. 3.

Table 2: Mildly irregular frame: comparison of the maximum displacement ratio u / H × 10 3 for di ff erent random frequency contents of the seismic action

Accelerogram 1 10 Max FULL 2.76 2.68 2.97 2.83 2.64 2.66 2.56 2.70 3.21 2.63 Max ROM 2.56 2.74 2.92 2.98 2.67 2.67 2.70 2.57 3.17 2.58 Error 7.27 2.39 1.44 5.39 1.48 0.28 5.41 4.87 1.30 1.76 2 3 4 5 6 7 8 9