Masegra castle in Sondrio

Mechanical analysis of the materials is only one of the steps to be taken during the planning process: the Italian Seismic Guidelines for Heritage Buildings explicitly states that indirect non-destructive testing can evaluate homogeneity in a construction’s mechanical parameters but cannot give reliable quantitative estimates. The direct parameters of masonry, especially which of strength, can only be ascertained through slightly-destructive or destructive testing. Calibration of non-destructive with destructive testing can be used to reduce the invasiveness of testing.

The castle was firstly analyzed for cracking and deformation pattern in order to identify a preliminary material and structural diagnosis. The planning was carried out as follows:

•     complete geometric analysis with identification of significant structural elements and their deformation or cracking;

•     horizontal coring with video camera survey on the elevated sections of masonry, the vaulted structure was analyzed through geo radar non-destructive testing and video camera inspections determining thickness of vaults and stratigraphy of flooring above. Chain tension was measured through vibrational dynamics and the characteristics of the attic through geometric tests and video probe prospecting.

•     mechanical masonry properties were evaluated through flat jacks to determine masonry tension and parallel flat jacks for deformation, wooden elements and their possible degradation were analyzed through penetro-metric testing using a resistograph;

•     sub vertical coring with inner endoscopic video-inspection was carried out to analyze the foundations and determine their geometrical plan and masonry foundation typology with, in certain cases, direct prospecting. Geotechnical and geophysical testing allowed for the analysis of the foundation

Damage variations on the north tower and dove tower were taken through high resolution removable strain gauge. Air temperature readings were also taken at the same time so as to compare how the two values were inter-connected.