Structural damage detection on a full-scale masonry cross-vault subjected to quasi-static cyclic loading tests

This paper presents the results of an experimental campaign for structural damage detection on a full-scale alternative-masonry cross-vault subjected to quasi-static cyclic tests. The masonry constituent material was composed of stabilised compressed earth blocks and soil-cement mortar. The cross-vault specimen presented a square plan with a span of approximately 3.20 m. Its boundary conditions consisted of two fixed corners that restrained displacements and rotations in all directions, and two corners that were placed over four-wheeled steel masses that enabled horizontal displacements. The masonry cross-vault was subjected to incremental horizontal cyclic load following a displacement-controlled approach to capture its in-plane shear failure. A total of 14 cyclic load sequences were applied to the specimen, reaching a maximum displacement of about 40 mm. The damage detection was evaluated in terms of frequency decrease and modal shape variations, estimated by operational modal analyses (OMA) technique carried out every two cyclic loads sequences considering ambient vibrations as excitation source. The Enhanced Frequency Domain Decomposition (EFDD) method implemented in the ARTeMIS Modal software estimated the specimen's frequencies. The results show an important decay in natural frequencies and variations of the first three mode shapes, especially when the vault experienced severe damage.