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International cooperation and technology transfer
Mussio, Luigi

the degradation of the materials, have to be
The results of thiis study, carried on before the
beginning of the restoration of the structure itself,
will be useful to compare the movements and
deformations of the structure during and after the
conservation works with the ones observed
A different approach is, on the other hand,
required, by the monitoring measurements carried
on to verify the safety of the structure during the
restoration. In this case the project both of the
control follows the experience aquired in years of
scientific wirk in the world of building deformations
monitoring. From this experience appears with
evidence the need of a continuous and automatic
control of the deformations and movemebts, but it
is at the same time clear that the project of the
monitoring system must take in account how the
work will be carried on in the way that the
instruments placed on the structure before the
beginning of the restoration works will be active
also during and after the works.
In the “Palazzo della Ragione” the restoration
regards in particular with the wooden cover of the
main hall. For this reason the control is mainly
voted to the study of the deformations of the part
of structure influenced by the restoration works.
These works mainly consist in the gradual removal
of the roof covering the main hall, in the inspection
of the wooden cover-carrying structures and in the
substitution of the wooden girders found in bad
conditions. At the end of the works is planned an
increasement of the global load.
In these years a large number of structures and
historical buildings have been subjected to static
continuous monitoring. These procedures,
consisting on placing some instruments on the
structure connected to an automatic data logger,
have shown their great importance in particular
when the high complexity deformation behavior of
historical buildings have to be monitored. The
large amount of data acquired through the
instruments placed in these structures, concerning
the environmental conditions (temperature,
humidity) and deformations, are usually finalized,
as before said, to highlight the deformations trend
and the correlation between environmental
parameters and structure deformations. It’s also
indispensable to filter the deformations in their
various frequency components (daily, seasonal,
yearly,...). The daily or seasonal cyclic
deformations can give important informations for
the analysis of the structure stress and
redistribution of loads due to the change of
environment parameters (temperature, ground-
water level, humidity, sun position...), but can
therefore hide in the years the permanent
deformations trend.
In several applications it is not possible to monitor
all the deformation and movements parameters
using automatic sensors, due to the costs or to the
particular measurements that can be needed. For
these reason it is often advisable to carry on a
static control that for some deformations or
movements analysis apply a classical, not
automatic topoographic approach. In many
applications the presence of an expert surveyors
can help to reach the solution to measurements
problems that cannot be performed with automatic
The automatic control of the Palace is composed
by three different kind of instruments. First of all
four long base extensometers, crossing the main
hall. An invar thread, 20 meters long, connect the
two internal walls of the palace. The thread is kept
strained with a 4 kg brass weight. The automatic
sensor is composed by a 5 thread 0-50 mm
potentiometer of 5 Kohm.
Five short base extensometers have been placed
across fessures present in the internal walls of the
palace. These sensors usually monitor small
deformations and for this reason, and to improve
the measurement accuracy, use a different
sensor. In particular a 5 thread 0-25 mm
potentiometer of 1 Kohm.
To monitor the temperature inside the palace 5
four thread PT100 temperature sensors have
been installed at different levels of the internal
walls. The data earning from these sensors have
also be used to evaluate the deformations, due to
the temperature, of the invar thread.
All the automatic instruments admit a direct
measurement with an analog comparator. In this
way even if the automatic sensor has a mis-
working the history of the deformations it is not
The data are stored in one main control unit that
receives the data from the sensors in a digital 16
bit format. In fact four small control unit, close to
the sensors, make the function on analog to digital
converter. The data are later transferred using a
RS485 protocol.
In this way the accuracy of the data acquired from
the sensors aren’t subjected to any degradation
due to the distance between the sensor and the
main control unit.