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the degradation of the materials, have to be 
monitored. 
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 
before. 
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. 
3. CONTINUOS AUTOMATIC MONITORING 
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 
sensors. 
4. THE AUTOMATIC CONTROL OF THE 
PALACE 
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 
lost. 
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.