Material Parameters Identification of Historic Lighthouse Based on Operational Modal Analysis

Area of Science:

• Structural Engineering
• Heritage Science
• Non-Destructive Testing

Background:

• Masonry structures, like historic lighthouses, require accurate material property identification for preservation and analysis.
• Non-invasive methods are crucial for heritage structures to avoid damage during material characterization.
• Existing databases for historic masonry material properties often lack comprehensive data.

Purpose of the Study:

• To identify material parameters (elastic modulus, Poisson's ratio, density) of a masonry lighthouse.
• To validate a numerical structural model using experimental data.
• To contribute to the database of historic building material properties.

Main Methods:

• Utilized a fully non-invasive approach for material property determination.
• Employed finite element method (FEM) for constructing an exact structural model.
• Applied operational modal analysis (OMA) with peak picking (PP), eigensystem realization algorithm (ERA), and Natural Excitation Technique with ERA (NExT-ERA) to obtain experimental frequencies and mode shapes.

Main Results:

• Successfully determined the elastic modulus, Poisson's ratio, and material density for brick, sandstone, and granite masonry.
• Validated the numerical model against experimentally derived natural frequencies and mode shapes.
• Identified optimal input combinations for PP and NExT-ERA, and averaged modal forms using ERA for enhanced accuracy.

Conclusions:

• The non-invasive method effectively identified key material parameters of the masonry lighthouse.
• The validated numerical model can be reused for future structural analyses of the lighthouse.
• The determined material properties enrich the scientific understanding of historic masonry.