Assessment of load bearing walls through dynamic tests. Application to Gaudi’s Palau Güell.

In this participation, the results of a series of dynamic tests for damage identification performed on a load-bearing wall in Gaudí’s Palau Güell in Barcelona are presented. The wall, of about 20 cm of thickness, is constituted by massive and hybrid stone blocks. The hybrid blocks are made of two external stone plates (4 to 5 cm thick) and an internal layer of mortar. About 250 dynamic tests were developed on 33 different stones, both massive and hybrid, not only to detect the boundary conditions and the typology of the blocks but also to detect the existence of damage. The tests were carried out with two different sets of the instrumentation: “One-sensor” tests were performed with the use of an impact hammer and one accelerometer, both placed on the same face of the wall. “Double-sensor” tests were also performed, using two accelerometers simultaneously placed on the two accessible faces of the stones. A comparative analysis of the time domain response between the faces was developed. Furthermore, a first approach for the analysis of the damping ratio was also implemented. The available dynamic information was enough to understand the full condition of the wall. The evidence of an accurate geometrical survey and of some corings confirmed the hypothesis generated by dynamic tests. Therefore, the technique is considered by the authors a promising alternative for the performance assessment of stone blocks and loading wall structures, aimed particularly as a non-destructive technique for historical constructions.