Wood NDT-2000 Session V.: Inspection of structure and structural components
NDT Determination of the Strength Loss of Deteriorated Wood by Using Ultrasonic Techniques and a Specific Wood Tester
Palaia Pérez-L., Galvañ Llopis, V. Chairs on Building Materials, Drs. in Architecture, Department of Architectonic Constructions, School of Architecture, Polytechnic University of Valencia. Camino de Vera s/nº, Valencia 46022, Spain. Cervera Moreno, F. Titular Professor, Dr Engineer, Department of Physics, School of Telecommunications, Polytechnic University of Valencia. Camino de Vera s/nº, Valencia 46022, Spain. Molina Nieto, R. Laboratory Assistant, Engineer. Department of Architectonic Constructions, School of Architecture, Polytechnic University of Valencia. Camino de Vera s/nº, Valencia 46022, Spain.
ABSTRACT
Facing the problem of restoration of timber structures, one of the most important steps on the diagnosis of decayed wood is to determine the strength loss of the material, to approach to a value to be considered for the design of structural members in service.
We have developed a system by using several NDT devices, which used in a combined way, may be useful for this purpose. One of these NDT methods consists on the validity of ultrasound techniques to determine the influence of the decay of wood in strength of wood, by means of probes of wood with different loss of weight 3 to 15%. The other method is based on the use of a penetration tester, Pylodin, a specific device for wood testing. The research developed tends to determine that the use of both systems provides enough information to approach to the loss of strength of a decayed timber structural member.
A great number of tests were done to valid the method, which were put in relation with compression strength testing of the probes. The tests were done in three specimens of wood, those more used in ancient buildings. The probes were 15 x 4,5 x 3 cm, air dried and without defects. It was considered, as well, the influence of moisture content and specific gravity.
Four different essays were developed. First series with clean wood to determine its mechanical characteristics. Second series to determine influence of moisture content. Third series to establish the variability of loss of weight of the probes, and diameter of holes, and fourth series to determine both loss of weight and moisture content influence together. All the essays were done with the NDT devices referred before, and compressive stregth determination.
Publication Source: Proceedings of the 12th International Symposium on Nondestructive Testing of Wood University of Western Hungary, Sopron, 13-15 September 2000, ISBN 963 7180 88 5 Publisher: University of Western Hungary, H 9400 Sopron, P.O.Box 132, FAX: +36 99 311 103
