Material Parameters Identification of Historic Lighthouse Based on Operational Modal Analysis

Abstract

In the present paper, the identification of the material parameters of a masonry lighthouse is discussed. A fully non-invasive method was selected, in which the material properties were determined via numerical model validation applied to the first pair of natural frequencies and their related mode shapes, determined experimentally. The exact structural model was built by means of the finite element method. To obtain experimental data for the inverse analysis, operational modal analysis was applied to the structure. Three methods were considered: peak picking (PP), eigensystem realization algorithm (ERA) and natural excitation technique with ERA (NExT-ERA). The acceleration’s responses to environmental excitations, enhanced in some periods of time by sheet piling hammering or by sudden interruptions like wind stroke, were assumed within the analysis input. Different combinations of the input were considered in the PP and NExT-ERA analysis to find the most reasonable modal forms. A number of time periods of a free-decay character were considered in the ERA technique to finally calculate the averaged modal forms. Finally, the elastic modulus, Poisson’s ratio and material density of brick, sandstone and granite masonry were determined. The obtained values supplement the state of the art database concerning historic building materials. In addition, the numerical model obtained in the analysis may be used in further cases of structural analysis.

Parametric Analysis of Failure Loads of Masonry Textures by Means of Discontinuity Layout Optimization (DLO)

“…In [ 7 ], an approach that uses upper bound limit analysis combined with non-linear dynamic analysis (a rocking analysis) was proposed. A general approach based on finite element method can be used [ 8 , 9 ]. When dealing with masonry wall, the effect of load direction on shear strength can be of importance [ 10 ], and of course the orthotropic nature of the material should be taken into account [ 11 ].…”

An Adaptive Operational Modal Analysis under Non-White Noise Excitation Using Hybrid Neural Networks

“…Recently, various methods for identifying modal parameters of time-invariant structures were proposed [7][8][9][10]. Additionally, the simplest and most typical one is the peak picking (PP) method [11]. In addition, the frequency-domain decomposition technique that has been widely studied by researchers [12][13][14][15] is constantly being improved; for instance, the enhanced frequency-domain decomposition (EFDD) algorithm can predict not only the natural frequencies, but also estimate modal damping ratios [16].…”

Special Issue: “Non-Destructive Testing of Structures”

“…The diagnostics of cultural heritage structures were the subjects of interest in the last two papers from this Special Issue [21,22]. Tomaszewska et al [21] investigated the problem of the modal identification of a masonry lighthouse. In the experiment, operational modal analysis was applied to the structure.…”

“…In the diagnostic process, the material properties were determined via numerical model validation applied to the first pair of natural frequencies and their related mode shapes, determined experimentally. As a result, the elastic modulus, Poisson's ratio and material density of brick, sandstone and granite masonry were determined [21]. Rucka et al [22] presented the results of the integrated ground penetrating radar (GPR) and ultrasonic testing (UT) inspection conducted on a historical floor.…”