A pilot project for the long-term structural health monitoring of historic city gates

Abstract

This paper reports on a pilot project for long-term structural health monitoring of historical city gates. This structural typology is what today remains of the defensive structures that characterised the medieval centres of many European cities. Even though in the last years the scientific community has paid great attention to the structural analysis and on the structural health monitoring of masonry towers, which are apparently similar to the typology of city gates, only a few studies explicitly approach such heritage buildings. In most cases, the surviving gates are immersed in the daily vehicular-traffic flows and hence continuously subjected to traffic-induced vibration. Consequently, a key point both for their conservation is the assessment of the optimal sensors position to be used for reliable structural health monitoring procedures. These issues are here discussed with reference to a specific case: the San Niccolò gate in Florence (Italy). First, an expeditious experimental campaign performed with a reduced number of accelerometers is reported. This test is aimed to identify a numerical model that is subsequently employed to design the optimal sensor position of long-term structural monitoring. This optimal sensor grid must be assessed to ensure a low-cost and sustainable dynamic monitoring system but, at the same time, to maximize the information contents.

Optimal placement method of multi-objective and multi-type sensors for courtyard-style timber historical buildings based on Meta-genetic algorithm

“…During the calculation of the damage sensitivity matrix, the structure was subjected to the white noise excitation with an amplitude of 0.05 times the acceleration of gravity. 28,41 The white noise frequency was set to higher than 2.56 times the maximum analysis frequency (set to 12 Hz), and the noise duration was set to 5 s. According to Equations ( 11)-( 13), the damage sensitivity of the whole structure can be computed. All DOF calculation results are converted to their corresponding components using the two-norm for display simplicity.…”

“…FIM and information redundancy were taken into consideration to solve the OSP problem for San Niccolo`city gate in Europe. 41 In summary, the following issues must be discussed in depth according to the current literature: (a) For multiple indexes corresponding to various monitoring objectives, the additivity problems caused by distinct value ranges must be addressed. Conventional standardization methods are difficult to implement since the value range is unknown and statistical indexes (such as maximum, minimum, mean, standard deviation, etc.)…”

“…FIM and information redundancy were taken into consideration to solve the OSP problem for San Niccolò city gate in Europe. 41…”

A Systematic Review of Structural Health Monitoring Systems to Strengthen Post-Earthquake Assessment Procedures

“…This method is based on the relation between observed displacements and modal responses using the Fisher information matrix, where a suitable sensor configuration results in the maximization of the norm of this matrix. In addition, in [ 64 ], a numerical model is used to assess the optimal sensor positioning and number to ensure the long-term monitoring of the structural health of historic structures. This is accomplished by first obtaining a numerical model based on experimental frequencies.…”

Effects of Environmental and Operational Conditions on Structural Health Monitoring and Non-Destructive Testing: A Systematic Review

“…Accordingly, the health of a structure can be defined as the present ability of a system to perform its intended function safely and cost-effectively against the anticipated risks during its service life. To ensure structural integrity, SHM systems have been developed for periodic health assessment [7] and employed for various structures, such as buildings [8][9][10][11][12][13], cultural heritage structures [14][15][16][17], bridges [18][19][20][21][22][23][24], underground structures [25,26], dams [27], offshore structures [28][29][30][31][32][33], wind turbines [34][35][36][37][38], ships [39][40][41][42], and aerospace infrastructure [43][44][45][46]].…”