PSI - Issue 64

Galić Josip et al. / Procedia Structural Integrity 64 (2024) 908 –917 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Table 2. Reinforcement in elements Element

Shear reinf. Φ 6 / 30 cm Φ 6 / 30 cm

Longitudal reinf.

Column V1, V2, V3 Beam V1, V2, V3

10 Φ 22 6 Φ 12

Found reinforcement is smooth and according to year of building is suitable Strengthening class for that kind of reinforcement is B 240, with yield strength f y = 240 Mpa in Galić etc (2023) 2.3. Numerical analysis of existing structure Based on the conducted research, existing building drawings, and a survey of the current condition, a numerical model of the existing structure was developed. Using this model, the resistance of the existing structure to seismic action was calculated. The seismic analysis was carried out according to HRN EN 1998-1:2011 and HRN EN 1998 1:2011/NA:2011.

Table 3. Input parameters for numerical analysis of existing building. Parameter

Value or input

Location a gR /g, T NCR = 475 y Location a gR /g, T NCR = 95 y

0.249 0.126

Importance factor, γ I

1.20

Ductility

DCM

The modal analysis was performed to determine the oscillation modes of the building structure. Regarding the behavior of the load-bearing structure, it is evident that the first mode represents translational oscillation in the longitudinal Y direction, the second mode represents torsional oscillation, while the third mode represents translational oscillation in the transverse X direction. The following figure illustrates the three modes based on the modal analysis of the building structure.

Fig. 6. First three modes of structure: (a) First mode Y direction translation f = 0,97 Hz, (b) Second mode torsion f = 1,55 Hz, (c) third mode X direction translation f = 1,58 Hz

Seismic calculation was conducted using the method of equivalent lateral force according to EN 1998, this method is useful for structures like moment-resisting frames. The building was evaluated based on three main criteria, including: control of horizontal displacement, calculation of the capacity of masonry walls, and reinforced concrete frame elements. The maximum elastic displacement resulting from the analysis was Δ y = 46 mm, while the allowable displacement for the building was 34 mm (H/500 criterion). The building did not meet the criterion for allowable horizontal displacement, indicating insufficient stiffness.