**7. Conclusions**

frequencies, modal displacements and damping factors. The first campaign of tests [32] have

The first two peaks are around frequencies values, about 1.25 and 1.7 Hz. Other peaks are present over 2 Hz. Two of them, around 2.5 and 2.7 Hz, are well defined in all tests. Secondary peaks, around 2.2, 2.3 and 2.6 Hz, are not always visible in all the responses; they indicate the occurrence of highly coupled modes. These peaks, however, are estimated to be less important: numerical analysis indicates that the participating mass of first two modes is at least 85% of

After retrofitting, all peaks are shifted to higher frequencies [33]. The first two are around 1.45 Hz and 2.12 Hz respectively. Other peaks are clearly visible around 2.6 and 2.95 Hz. Secondary peaks, which are not always visible in all the responses, are recognisable even in this case. Higher frequencies are a consequence of the increasing stiffness brought about by retrofitting. It is interesting to observe that now the responses of a pair of accelerometers are basically identical, at least in the range of frequencies examined. This is a clear indication that the retrofitting had improved the link between the longitudinal walls. Other dynamic testing have been performed on the facade [34] which have permitted to evidence that out-of-plane local

**Figure 12.** Installation phases of the monitoring system at the Basilica di S. Maria di Collemaggio: a) b) sensor posi‐ tioning on the central walls of the nave, c) sensor positioning beyond the facade, d) f) sensor views, g) phase of on-site

permitted to recognise at least four major resonance peaks in the range 0.8÷3.0 Hz.

total mass in the transverse direction of the church.

230 Engineering Seismology, Geotechnical and Structural Earthquake Engineering

testing, h) sensor positioning at the end of the nave walls.

The chapter aims to present the rapid development in the transfer to the real applications of the available technology in the sector of structural control and health monitoring, occurred at L'Aquila immediately after the 2009, L'Aquila earthquake. The benefits in the application of these emerging technologies are still under verification and observation. For the performance evaluation of the installed seismic protections systems, only the occurrence of a relative strong seismic motion, will clearly evidence the benefits introduced in the territory. Differently, the large amount of activities concerning material and in-situ testing together with small or longterm monitoring will surely increment the knowledge regarding the real behaviour of complex masonry or reinforce concrete structures. The amount of obtained data from this large campaign of testing, conducted with different techniques and aims, is in many cases larger than the real possibility of a deep discerning. Indeed a complete extraction of valuable information useful for the understanding of the material and structural behaviour of the large amount of buildings, infrastructure and historical monuments is still undergoing. The presented overview, even if conducted more on an informative level than in a deep scientific manner, remains a valuable starting point for searching innovative procedures and devices in the considered research field. The above references will permit a deeper analysis on specific questions and further publications will make into evidence specific novel findings, developed during the difficult path of doing innovative research in a territory in which a natural disaster has strongly modified the habitual activities conducted before the event.

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