PSI - Issue 44

Giacomo Iovane et al. / Procedia Structural Integrity 44 (2023) 1864–1869 Giacomo Iovane et al. / Structural Integrity Procedia 00 (2022) 000 – 000

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2.2. Case studies and design data The design criteria are applied to 5 case studies: Moment Resisting Frame (MRF), Concentric Braced Frames with a single diagonal (D-CBF), in X configuration (X-CBF) and V configuration (V-CBF), and Eccentric Braced Frame (EBF). Specifically, 2D single-storey frames equipped with steel links are studied. Reference is made to a single storey structure 3m high, with a rectangular plan layout having two bays, 6m long, for a total length of 12m, in the y transverse direction and three bays, 6m long, in the longitudinal x-direction, for a total length of 18m (Figure 1). The floor structure is oriented along the y-direction supported by secondary beams in the x-direction. The vertical seismic resistant system consists of 4 frames, 2 for each direction. The roof is assumed as composed by timber planks with a thin concrete slab. The structural permanent load is equal to G 1k = 0.22kN/m 2 and the non-structural permanent load is equal to G 2k = 1.30kN/m 2 . The variable load considered is the service load Q k = 2.00kN/m 2 (Tab. 3.1.II, NTC2018). The seismic action is defined with reference to the seismic zone 1, according to OPCM 3274 (03/20/2003) for the sake of brevity, corresponding to the peak ground acceleration a g = 0.35g, and a “category B” soil.

MRF

V-CBF

X-CBF

Seismic resistant frame

Steel link

Plan layout [m]

D-CBF

EBF

[cm]

Fig. 1. Case studies: geometrical features.

Seismic resistant structures have been designed both as non dissipative and dissipative in DCM. For non dissipative structures a behaviour factor q=1 is assumed, consequently the design spectrum is the elastic one. For DCM dissipative structures, the behaviour factor q d is assumed as equal to 4 for MRF, X-CBF, D-CBF and EBF, and 2 for V-CBF (§2.2), considering the behavior factor values of the same structural types made of steel, according to Eurocode 3 (EN 1993-1-1: 2005), considering that the ductility is in charge of the steel links. The response spectra for both non-dissipative and dissipative structures are defined at Life Safety (LS) and Damage (D) Limit States (LS). Loads are combined according to NTC2018 (§ 2.5.3), considering the Ultimate (ULS) and the Serviceability Limit States (SLS, rare and semi-permanent combinations) for non-seismic combinations, the Life Safety (LS) and Damage (D) Limit States for seismic combinations. With regards to materials, for timber members

and steel links, GL24h and S235 grades, respectively, are used. 3. Structural design and seismic performance evaluation 3.1. Linear dynamic analysis

For the design of structures, at first static linear analyses and then linear dynamic analyses are carried out, through the structural calculation program SAP2000 (v18). Design results are shown in Table 1 in terms of structural sizes, design force at SLV (F d,SLV ), structural mass (M) and ΔM factor, which define s the structural mass reduction of the dissipative (D) structures as respect to the (ND) non-dissipative ones, it being quantified as ΔM= (M ND -M D )/M ND , where M ND and M D are the structural mass of non-dissipative and dissipative structures.