Empirical estimates of dynamic parameters on a large set of European buildings

Abstract

During a three year-period, the participants of a NATO Science for Peace project performed ambient noise measurements inside buildings in four European countries. This paper reports the results relevant to reinforced concrete (RC) buildings with height in the range 1-20 floors. The total number of such buildings surveyed is 244. The most striking feature is the similarity of the height-period relationships in the four countries, which allowed the treatment of the all measurements as a single database. We found no significant correlation with other variables, and calculated a regression that is very similar to other empirical height-period relationships and quite different from code provisions and theoretical models.

Evaluation and considerations about fundamental periods of damaged reinforced concrete buildings

“…Moreover, in a noisy environment with ongoing restoration and demolitions, HVSR has the same target in the building and in the soil: that of separating the true shear response of the investigated object from the propagating noise that can mask the true eigenfrequencies. In previous works, HVSR has proved to be a reliable proxy of SSR to estimate fundamental frequencies, as demonstrated on a large set of Italian buildings by Gallipoli et al (2009), provided that the measurement points are carefully selected to avoid membrane modes of the floors and other possible problems as described in the appendix of the paper by Gallipoli et al (2010). Table 2 reports the analysis results for each building, with age classes, damage levels and building height.…”

“…Table 2 reports the analysis results for each building, with age classes, damage levels and building height. Figure 5 shows the comparison between the periods of the damaged RC buildings with those obtained for undamaged RC Italian and European buildings (Gallipoli et al, , 2010. It is worth noting that the theoretical equation provided by the codes returns an over-estimation of periods also for the highest damage level (DL = 4).…”

“…The use of a fast procedure and a portable instrument allows studying a large number of buildings during an earthquake-related emergency. Gallipoli et al (2009Gallipoli et al ( , 2010 and Ditommaso et al (2010Ditommaso et al ( , 2012) have compared several techniques for structural dynamic identification: ambient noise vibrations are very useful for the characterization of the fundamental frequency and the related modal shape (if more than one station has been used). In this work the frequencies have been estimated using ambient noise recordings by means of a portable three-directional tromometer (Micromed Tromino).…”

“…On the contrary, the theoretical equation provided by the codes returns periods that are an over-estimation even when this level of damage is observed. This disagreement has to be considered taking into account the construction practices used in each country, with the need to perform a similar investigation and to define a relationship based on typical Italian and European buildings, as showed in previous works by Gallipoli et al (2009Gallipoli et al ( , 2010, Guler et al (2008), and Oliveira et al (2010) for undamaged RC buildings. …”

“…ATC, 1978;BSSC, 2003;CEN, 2005;NZSEE, 2006) provide period-height empirical expressions, usually set up with an elastic force-based design in mind. The recent research into earthquake engineering shows that the fundamental periods estimated by numerical models are often significantly different than those obtained when using an experimental approach (Gallipoli et al, , 2010Oliveira and Navarro, 2010;Michel et al, 2010). These differences are probably due to the fact that the dynamic properties of buildings are evaluated using numerical analyses based on inaccurate FE (finite element) models, based on too simplified models which inadequately reproduce the dynamic behaviour of real structures.…”