PSI - Issue 26

L. Martelli et al. / Procedia Structural Integrity 26 (2020) 175–186 Martelli et al. / Structural Integrity Procedia 00 (2019) 000–000

182

8

Primary structure

Coupled system

DLS

LLS

DLS modes

LLS modes

DLS

LLS

DLS modes

LLS modes

0.100

0.100

0.075

0.075

0.050

0.050

Se [g]

Se [g]

0.025

0.025

0.000

0.000

0

1

2

3

4

0

1

2

3

4

T [s]

T [s]

Fig. 7. Horizontal component of elastic pseudo-acceleration response spectra of both structural systems.

Coupled system Primary structure

0.100

0.075

0.050

∆a g ,3

Se [g]

∆a g ,1

0.025

0.000

0

1

2

3

4

T [s]

Fig. 8. Elastic pseudo-acceleration response spectrum for the top three vibration modes, LLS.

∆a g,i Table 2. ∆a g variations between the two systems.

Mode

variation

1 2 3

19% 76%

129%

3.4 Seismic response The linear dynamic analysis has allowed to find seismic response characteristics like maximum floor displacements, inter-storey drift ratios and base shears; they are the main practical quantities to monitor the behaviour of structures from a seismic and vulnerability point of view. Tables 3 and 4 represent peak floor displacements for which Damage and Life-safety Limit States have been considered for the original structure and the combined primary-exoskeleton system; the former also indicates DLS inter-storey drift ratios.