PSI - Issue 44
Maria Maglio et al. / Procedia Structural Integrity 44 (2023) 550–557 M. Maglio, R. Montuori, E. Nastri, V. Piluso / Structural Integrity Procedia 00 (2022) 000–000
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3.6. Design of columns For columns in DC2, resistance and stability should be verified in compression, bending and shear considering the most unfavorable combination of , and from Formulas (17) (prEN1998-1-2, 2021): = , + , = , + , = , " + " , (17) where , , , and , are the effects of the non-seismic actions in the seismic design situation. , , , and , are the effects of the design seismic action. is the seismic magnification factor and is = 2 for Multi-storey MRFs, “+” means combined with + or – sign. 4. Numerical application To evaluate the effectiveness of the rules described above a numerical application is reported with reference to the scheme shown in Figure 3. The structural typology examined is a spatial Moment Resisting Frame (MRF) and for the application only the inner frame is considered because it is the more stressed. The material adopted is S355 steel grade, the permanent loads are 4.00 kN/m 2 on floors and roof, 0.12 kN/m 2 for the external walls while the live loads are equal to 3.50 kN/m 2 for the current floor and 3.00 kN/m 2 for the roof. The design horizontal forces have been determined according to the SD spectrum reported in Fig. 2. Beams are designed to withstand vertical loads and they are increased to satisfy the limitation for structural deflection. Columns are designed considering the soft storey mitigation rule (Eq. (11)). Moreover, the requirement reported in Eqs. (16) and (17) were respected as well as the control of second order effects and the limitation of inter-storey drift. Table 2 reports the profiles that satisfy all the design conditions and the values for the checking of the sensitivity to second order effects and drift limitation at SD limit state. For the validation of the design procedure a push-over analysis is carried out to evaluate the collapse mechanism typology and confirm the accuracy of the proposed design methodologies, based on the new EC8 rules. The horizontal actions are distributed to be compliant with the first vibration mode of the structure ( 1 = 1.03 ), according to the lateral force method defined in prEN1998-1-2 (2021). In Figure 4 the pushover curve (left) and the collapse mechanism of the structure (right) are reported.
Fig. 3. Plan and Elevation configuration of the building
Columns , [m] , adm [m] [kN] [kN] θ [-] [-] interval HE 280 B 0.04 0.07 2595.97 392.09 0.039
Table 2. Beams and columns sections, interstorey drift and sensitivity to second order effects Storey Beams
1 2 3
IPE 550 IPE 550 IPE 550
HE 260 B HE 240 B
0.04 0.03
0.07 0.07
1717.94 839.90
314.14 195.11
0.033 0.019
0.039
θ≤ 0.10
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