A team of engineers from the
University of Seville (US) has created
a system for monitoring historical monuments by remote control and
detecting possible damage. Five years ago the researchers placed
various sensors on the Giraldillo, the sculpture that crowns the
Giralda, and now they are publishing the results in the journal
Structural Health Monitoring.
"The system has been connected to the Giraldillo to register
different variables associated to the mechanical response of this
sculpture, such as meteorological actions or conditions that it is
subjected to, but it could be used to monitor other historical
monuments", Mario Solís, main author of the study and
professor at the Escuela Técnica Superior de Ingenieros
(Advanced Technical College for Engineers) of the US, explained to
SINC.
The Giraldillo, a Renaissance sculpture that acts as a weather
vane on the top of the Giralda, was taken down and restored between
1999 and 2005, at which point the researchers took the opportunity
to put on sensors which have allowed them to monitor it up until
now.
The results of the study, published in the last edition of the
journal Structural Health Monitoring, indicate that the weather
vane sculpture requires a wind speed of 10 m/s to move and
positions itself according to this meteor 40% of the time, the
temperature fluctuates from 0ºC registered on the exterior to
48 ºC measured by an internal probe, and no abnormal values
are recorded in the vibration frequencies and the mechanical
response.
"The system provides information of great interest for studying
the behaviour and state of preservation of the Giraldillo",
Solís highlights, which confirms that this technique "could
not only be applied to detect structural damage in other monuments
of historical heritage, but also in machinery and aero spatial
components".
How to monitor the Giraldillo
To determine the environmental conditions surrounding the
statue, the scientists installed two temperature and humidity
probes (one external and another on the inside of the ball on which
it stands), and a third to calculate the corrosion of the bronze
pieces that it is composed of.
The cables for the sensors are centralised in a terminal with a
40 metre cable leading into the data acquisition system. This is
located in the Body of the Clock of the Giralda, the highest point
of the tower, which can be easily accessed to carry out programming
and maintenance tasks. From there, through an internet connection
or via traditional remote control information can be sent to any
control centre.
The magnitudes registered are velocity and direction of the wind
(this is the main mechanical action that impacts the monument), the
degree of flexion of the rod that supports the statue on the tower
(to detect curvatures), and the measurement of vibrations, through
six accelerometers and four levels.
SOURCE