Traditional vs innovative structural health monitoring of monumental structures: A case study

Abstract

This work reports an experimental comparison between two measurement techniques of crack openings: a traditional method based on a mechanical device and the OTTO system based on fiber optic sensors and developed by CELM. The main characteristics of both methods are presented, with their main advantages, drawbacks, and peculiarities. The testing campaign conducted on a historical church erected in the first half of the eighteenth century is then described in detail. Cracks evaluation has a key role in the safety assessment of a monumental building and it is the base for a proper restoration design and intervention plan. The measurements monthly collected using the two described methods are compared and the performances of the two monitoring systems are discussed from both technical and economical points of view. Of particular interest are the unique characteristics of fiber Bragg gratings (FBG) sensors including their noninvasiveness and their extremely high precision in both displacement and time resolutions. These features make FBG sensors the ideal candidates for long term or not invasive monitoring. On the other hand, mechanical measurements remain the best candidates for initial or sporadic measurements. Copyright © 2010 John Wiley & Sons, Ltd.

Crack detection limits in unit based masonry with terrestrial laser scanning

“…length and width). Mechanical probes and electronic sensors are generally used [3][4][5]. However, while such instruments offer high precision for crack measurement, most have significant limitations: (1) predefined permanent positions on the structure; (2) prefixed, uniaxial measurement; (3) limited measurement range; (4) physical access requirements, and/or (5) considerable cost.…”

Laboratorial test monitoring applying photogrammetric post-processing procedures to surface displacements

“…Other techniques recently developed include: shearography, digital image correlation, laser speckle analysis, thermal imaging and laser scanning vibrometry [1,2]. With these, positioning is no longer a drawback.…”

A new device for stress monitoring of ancient masonry buildings: Pilot study and results

“…However, structural health monitoring (SHM) is an engineering technique that monitors, verifies, and informs about the condition or changes in the condition of a structure so that engineers are able to obtain trustworthy information for management, decision making, and to guarantee the safety of users . As a result, monitoring systems undoubtedly contribute to knowledge of the evolution of specific processes before, during, or after an intervention.…”