Fiber optic strain gages for stress analysis by means of the hole drilling technique

Abstract

ABSTRACT: The article deals with the application of the hole drilling technique on structural elements of architectural heritage constructions by using eight fiber optic strain gages. The objective of the research is the on site deduction of the stress state on stone masonry of architectural heritage constructions. The hole drilling method is a Minor Destructive Testing (MDT) giving information about the Principal Stresses of the local stress state around the measured zone and, in consequence, it favours the estimation of the stresses associated with a certain direction, for example the vertical stress of a stone masonry element. Fiber optic technology allows the storage of the strains in the strain gages even when the unit of measure is temporarily not connected. Thus it will be able to monitor the stress measurements as a time function. The tests carried out have compared the applied loads in a laboratory machine with the results obtained by the hole drilling technique through fiber optic strain gages. Until now only resistive strain gages have been used. In this sense the contribution is innovative with an evident advance towards the complete structural characterisation of stone masonry structural elements.