Damage Detection in Metamorphic Stone Blocks Utilizing Impact-echo Testing and Modal Analysis

Authors

Alexander C. Jording, University of Nebraska LincolnFollow

Date of this Version

5-2012

Document Type

Article

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of the Requirements For the Degree of Master of Science, Major: Architectural Engineering, Under the Supervision of Associate Professor Ece Erdogmus, PhD. Lincoln, Nebraska: May, 2012

Copyright (c) 2012 Alexander Charles Jording

Abstract

Existing buildings decay with the passage of time, and as a result, continually require maintenance or rehabilitation. When considering existing structures, testing is often necessary to complete structural analysis in preparation for rehabilitation or repair. Non-destructive testing provides a structural assessment method applicable to a variety of materials and structures. The hypothesis of this research is that impact-echo testing, one of the many NDT techniques, can be adopted to develop a reliable and standardized method to assess the condition of rectangular metamorphic stones. After the baseline material parameters and general response to impact-echo testing were established, a novel method to perform real-time on-site block assessments was developed. The methodology is developed using an international research project at Antiochia ad Cragum, near present-day Gazipaşa, Turkey, as a case study for structural assessment conditions. Blocks from the 3^rd century Imperial Roman temple at Antiochia ad Cragum, serve as the primary reference for this study. Theoretical values based on eigenvalue analysis when compared with finite element analysis results provided a correlation to within 2.4%. Frequencies from impact-echo testing from a sample block cast out of a similar density material are compared with theoretical eigenvalue analysis values, resulting in errors of less than 6%. As a result of this research, existing impact-echo methods have been validated for applicability on metamorphic stones and mortar blocks. Furthermore, a real-time impact-echo analysis program has been developed to assess stones and characterize their structural integrity simultaneously. These findings will benefit engineering and archaeological research teams wishing to evaluate rectangular stones. In addition, these techniques and methods, with minimal alteration, can be applied to a variety of materials including other types of stone, concrete, and even wood.

Adviser: Ece Erdogmus