PSI - Issue 44

Gianluca Salamida et al. / Procedia Structural Integrity 44 (2023) 131–138 Gianluca Salamida et al. / Structural Integrity Procedia 00 (2022) 000–000

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Fig. 3. Geometry of the hotels buildings studied: (a) reinforced concrete and masonry mixed building; (b) 9-storey RC hotel building.

2.3. Displacement demand The structural response of the buildings described above was studied through non-linear static (pushover) analyses. The various buildings were studied for different combinations of mechanical parameters and for each of them, different pushover analyses were carried out. In particular, two different horizontal force profiles are considered: one proportional to storey masses and one proportional to the fundamental vibration mode shape. Pushover analyses were conducted on the two main horizontal directions of the buildings; moreover, both positive and negative push directions were considered for three-dimensional models. The relevant number of capacity curves obtained for each building, due to permutations in mechanical parameters and in some cases to different configurations, aims at considering the effect of uncertainties. Displacements capacity limits were defined following the criteria prescribed by Italian Building Code (NTC 2018) depending on the structural typology. Subsequently, capacity curves were linearized and parameters of equivalent SDoF systems were evaluated in order to apply simplified methods to calculate displacement demands. The Capacity Spectrum Method (CSM) and Guerrini method (Guerrini et al. 2017) were applied to masonry buildings, while the IN2 method (Dol š ek and Fajfar, 2005) was applied to RC buildings with 2, 3 and 4 storeys, which manifested a significant strength degradation; for the 9-storeys RC building reference was made to CSM and N2 method (Fajfar and Ga š per š i č , 1996), since the infills influence in strength degradation resulted low. The seismic input is represented by the acceleration spectrum calculated from the accelerometric recording of a given station. In the case of the N2 and IN2 methods, which require the use of a Newmark-Hall type spectra, the spectrum is regularised to the appropriate shape using a least-squares procedure. For each of the capacity curves derived, displacement demands are estimated in order to predict which limit states are exceeded. Results are displayed by the GMAT software as a histogram. Fig. 4 shows an example of results on potential damage to two types of residential buildings, with reference to the shaking recorded at the Mirandola station on 29 th May 2012.

Fig. 4. Potential damage obtained considering the Mirandola station spectra (29 th May 2012 Emilia shock): (a) model M1_BM for pre-1919 brick masonry buildings; (b) model RC3 for 4-storey RC frame buildings.