discrepanze tra relazioni sperimentali e teoriche altezza ... · stato dell’arte e nuove proposte...

Discrepanze tra relazioni

sperimentali e teoriche altezza-

periodo degli edifici:

stato dell’arte e nuove proposte

Maria Rosaria Gallipoli and the BORA working team-

group on measurements on buildings

BORA working team- group on measurements on buildings

Co-coordinators: Philippe Gueguen and Maria Rosaria Gallipoli

Participants:

Angelo Masi, Bertrand Guillier, Christos Karakostas, Clotaire Michel,

Daniele Spina, Felice Ponzo, Manuel Navarro, Marco Mucciarelli, Vasileios Lekidis

Period-height relationship

T=C*Hα

Numerical expressions for the

fundamental periods of various

structural types

Housner and Brady (1963), Chopra and

Goel (1997; 2000), Hong and Hwang

(2000), Tremblay (2005),

Chrysanthakopoulos et al. (2006), Guler

et al. (2008), Hans et al., 2005 and

Verderame et al. (2010). Additionally,

shear-wall dominant systems have been

examined by Goel and Chopra (1998),

Lee et al. (2000), Balkaya and Kalkan

(2003), and Ghrib and Mamedov (2004).

Kwon and Kim (2010) for an extended

review for.

Experimental estimation of main

frequencies from seismic

ambient noise recordings

NATO Science for Peace project

“Assessment of Seismic Site

Amplification and Seismic Building

Vulnerability in the FYR of Macedonia,

Croatia and Slovenia” Gallipoli et al.,

(2009; 2010);

other projects (Farsi and Bard (2004);

Guler et al.(2008); Michel et al. (2008;

2010); Navarro and Oliveira (2005;

2006)

In all following slides black/grey dots

and lines are numerical estimates.

Colored dots and lines are experimental

estimates.

Comparison between numerical and experimental

period - height relationship

Estimation of building periods:

Seismic Ambient Noise vs Weak Motion

How different are the US buildings from European ones?

Numerical period-height relationships are typically provided

dependent only on the structural type (concrete frames, steel frames,

masonry, etc.), but not often they take into account other important

structural characteristics such as:

– presence/absence of infill walls (bare frame or infilled frame).

Dolsek et al. (2004); Amanat and Hoque (2006); Kose (2009);

Crowley and Pinho (2010); Ricci et al. (2011).

– flexibility of soil and soil-structure interaction effect

Stewart et al. (1999); Ghrib and Mamedov (2004); Aviles et al.(2002);

Bhattacharya and Dutta (2004); Khalil et al. (2007).

– period drop

Dunand et al. (2006); Calvi et al. (2006); Goel and Chopra (1997,

1998, 2000), Vidal et al. (2013), Ditommaso et al. (2013)

Numerical relationships ≠ Experimental relationships

such disagreement may be due

to these factors?

The effect of infill walls:

Bare Frame or Infilled Frame

bare frame bare frame with infills

The effect of infill walls: Bare Frame or Infilled Frame

Guler et al., 2008

Mucciarelli and

Gallipoli, 2007

base

free-field = foundation

top

free-field = building-foundation system

top

base = building

top

base = building

What are we really measuring on buildings?

The effect of infills and flexible bases

Rock/stiff soil

Soft soil

The effect of period elongation

1a) Variation in elastic domain

Moderate earthquake (PGA between 0.1 and 1m/s2), still in the

elastic domain (Hans et al. 2005; Michel et al. 2008, 2010).

The opening of cracks induces non-linearities, that produce a

frequency decrease reaching 35%. (Dunand et al. 2006)

2b) Frequency decrement due to damage

Goel and Chopra (1997, 1998, 2000)

It seems that a value of 60% drop in frequency is a limit

before the collapse according to data compiled by Calvi et al.

(2006).

Pollino seismic sequence - Rotonda school (Stabile et al., 2013)

Variation in elastic domain: temporary period elongation

40%

The effect of damage: permanent period elongation

Vidal et al., BEE, 2013

Ditommaso et al., NHESS, 2013

1. Objective

The main objective of this activity is to propose an extensive review of ambient vibrations

based experiences for earthquake engineering only. This review may define the first draft of

guidelines on the use of ambient vibrations experiences. After discussion, we propose also

the review be focused on European activities only, as a preliminary state-of-the-art

documents.

Several activities can be browsed:

- ambient vibrations for reducing epistemic uncertainties of fragility curves

- ambient vibrations for post-event short-term assessment of building state and integrity.

- ambient vibrations for model updating in dynamics of structures

Item 1 - Application

Item 2 - Methods and signal processing

Item 3 - Interpretation of variation of frequency

Item 4 - Damping

The first draft will be prepared for 2ECEES in Turkey (August, 2014).