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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As it is apparent, in general the dissipative structures have a lower mass as respect to the non dissipative ones, this proves the convenience of the dissipative design also for timber seismic resistant structures. In particular, the dissipative V-CBF and MRF structures show the lowest mass reduction as respect to non dissipative design, with ΔM= 19%. This is due to the lower value of the behaviour q factor (q=2) in case of V-CBF and to the DLS seismic verification of horizontal displacements in case of MRF. Dissipative D-CB F with ΔM= 31%, X-CBF with ΔM=3 6% and EBF with ΔM= 43% follow.

Tab. 1. Member sizes and structural parameters for non-dissipative and dissipative structures.

Element sizes [mm]

Structural parameters

Structural type

Beam

Column

Diagonal

F d,SLV

M

ΔM [%]

Timber 300x420 280x400 180x320 160x320 180x320 160x320 220x420 200x400 280x440 200x400

Link

Timber 420x480 340x460 300x320 240x260 300x320 240x260 280x300 240x280 340x360 220x260

Link

Timber

Link

[kN]

[kg]

ND

-

-

- -

- - -

265.28

75.42 61.43 62.55 39.93 51.27 35.53 52.99 43.01 68.18 38.67

MRF

19

D

IPE220

HE180B

88.65

ND

- - - - - - -

- - - - - - - -

230x230 160x160 240x240 180x180 190x190 160x160 200x200 160x160

263.76

X-CBF

36

D

30x30x2.5

88.14

ND

-

263.76

D-CBF

31

D

30x30x2.5

88.14

ND

-

260.38 144.80 260.31

V-CBF

19

D

50x50x3

ND

- -

EBF

43

D

IPE160

86.99

3.2. Non-linear static analysis The seismic behavior of the dissipative structures is examined through non-linear static analyses. Timber members and steel links are modelled as “ beam elements ” . For timber, the material is modelled with an elastic behavior, while for steel links finite element, lumped plasticity is modeled with a perfect elastic-plastic behavior of the material (FEMA 356, 2000). In particular, in MRFs the links at the ends of the beams and at the base of the columns are subjected to bending, the compression force being negligible, and the plasticity is assumed as concentrated into the middle of the link; in EBFs the links in the beams are designed as long-link, they are mainly subjected to bending and the plasticity is concentrated at the link ends; in D-X-V-CBFs the links in the diagonals are subjected to compression and tension and the plasticity is assumed as concentrated into the middle of the link. Results of the numerical analyses are provided in terms of push-over curve, q-factors ( Fig. 2).

q d (DCM) q LS Δ qLS q CP Δ qCP q CM Δ qCM

Structural type

MRF

4

5.8 1.45 8.6 2.15 14.7 3.68

X-CBF

4

7.9 1.98 9.1 2.28 10.7 2.68

D-CBF

4

5.9 1.48 6.8 1.70 8.1 2.03

V-CBF

6.2 3.10 7.2

3.60 8.7

4.35

2

EBF

5.4 1.35 6.3

1.58 7.7

1.93

4

Fig. 2. a) Push-over curves and b) q-factor at LS, CP and CM ultimate conditions.