Non-destructive experimentation : Dynamic identification of multi-leaf masonry walls damaged and consolidated

The dynamic monitoring of multi-leaf masonry wall is here proposed. The results of non-destructive tests
carried out in this work are a first part of a wider testing campaign aimed at verifying the structural
performance of masonry walls. Multi-leaf masonry walls constitute the composite construction typology
most widely adopted in historic buildings. This aspect, together with the intrinsic structural complexity,
heterogeneity and irregularity, directs the present research towards a topic not yet sufficiently investigated
by the scientific community. In this paper, the case of multi-leaf masonry wall has been investigated,
and with the aim of reproducing historical buildings structural elements, three different
typologies of multi-leaf masonry walls have been considered: (i) full infill, (ii) damaged infill, (iii)
consolidated infill.
Several masonry specimens of the above-described typologies have been built and tested in lab. The
dynamic parameters, such as frequencies, modal shapes and damping ratios have been identified
through the output-only procedure and the data were processed through the Least Square Complex
Frequency (LSFC) estimator; the analysis of results allowed to evaluate the structural integrity, the
efficacious of consolidating intervention and the potential performance mechanisms of different complex
multi-leaf masonry walls.
Experimental results are compared with numerical Finite Elements models. Composite multi-leaf
masonry is modeled as an equivalent continuum obtained through a full 3D homogenization procedure.
The mechanical properties of component materials have been obtained in lab by tests and then used
to model the masonry at the micro-scale in order to derive the mechanical properties to be adopted at
macro-scale. A parametric natural frequencies analysis is performed in order to calibrate the model by
the comparison whit the experimental measures.