Numerical and experimental analysis of the leaning Tower of Pisa under earthquake

Twenty years have passed from the most recent studies about the dynamic behavior of the leaning Tower of Pisa. Significant changes have occurred in the meantime, the most important ones concerning the soil-structure interaction. From 1999 to 2001, the foundation of the monument was consolidated through under-excavation, and the "Catino" at the basement was rigidly connected to the foundation. Moreover, in light of the recent advances in the field of earthquake engineering, past studies about the Tower must be revised. Therefore, the present research aims at providing new data and results about the structural response of the Tower under earthquake. As regards the experimental assessment of the Tower, the dynamic response of the structure recorded during some earthquakes has been analyzed in the time- and frequency-domain. An Array 2D test has been performed in the Square of Miracles to identify a soil profile suitable for site response analyses, thus allowing the definition of the free-field seismic inputs at the base of the Tower. On the other hand, a synthetic evaluation of the seismic input in terms of response spectra has been done by means of a hybrid approach that combines Probabilistic and Deterministic Seismic Hazard Assessment methods. Furthermore, natural accelerograms have been selected and scaled properly. A finite element model that takes into account the inclination of the structure has been elaborated, and it has been updated taking into account the available experimental results. Finally, current numerical and experimental efforts for enhancing the seismic characterization of the Tower have been illustrated

Seismic Reassessment of the Leaning Tower of Pisa:Monitoring, Site Response and SSI

The Tower of Pisa survived several strong earthquakes undamaged over the last 650 years, despite its leaning and limited strength and ductility. No credible explanation for its remarkable seismic performance exists to date. A reassessment of this unique case history in light of new seismological, geological, structural, and geotechnical information is reported, aiming to address this question. The following topics are discussed: (1) dynamic structural identification based on recorded earthquake data; (2) geophysical site characterization using a two-dimensional array; (3) seismic hazard and site response analysis considering horizontal and vertical motions; and (4) soil-structure interaction (SSI) analysis calibrated using lab and field data. A substantial shift in natural period, from about 0.35 s to over 1 s (a threefold increase, the largest known for a building of that height) caused by SSI, a wave parameter (1∕σ) of about 0.3, and a minor effect of vertical ground motion are identified and may explain the lack of earthquake damage on the Tower. Recommendations for future research, including the need to establish a seismic bedrock deeper than 500 m, are provided

Ruolo della duttilità dei nodi sul comportamento sismico dei telai in c.a

Atti Conferenza Plenaria - Murst Cofin 99 - Firenze 200

CHAPTER 8: WATER TANKS – A CASE STUDY

The proper functioning of pipelines and water supply systems involves relevant social and economic aspects, so that their maintenance in the optimal conditions is of primary importance. Considering the financial commitment related, it is necessary that interventions are carefully planned and optimally designed, which can be reached only after accurate surveys and investigations. In the present chapter an example is presented concerning the static and dynamic assessment of a hanging water tank, built with r.c. structure, around 1960

Dynamic soil-structure interaction of the Leaning Tower of Pisa

Most recent studies about the dynamic behavior of the leaning Tower of Pisa which consider soil-foundation-structure interaction date back to twenty years ago. From 1999 to 2001, the foundation of the monument was consolidated by means of under-excavation and the "Catino" at the basement was rigidly connected to the foundation. Meanwhile, significant progresses have been made in the field of ear-thquake engineering. Therefore, the need exists to assess the dynamic behavior of the Tower in light of the novelties occurred in the past de-cades. In the present study, the mechanical characteristics of the foun-dation have been calibrated comparing the outcomes of the experi-mental dynamic monitoring with the results of the finite element anal-ysis performed on a simple but effective model. Scenario earthquakes for return periods equal to 130 and 500 years and some preliminary results of the Array 2D test performed on the Square of Miracles are also presented