Risk Management and Maintenance Strategies for Timber Structures

Dr. Jochen Köhler
Swiss Federal Institute of Technology ETH Zürich, Switzerland
Short Curriculum Vitae

One of the pre-requisite of the successful and frequent utilisation of building materials in construction is that the buildings performance in regard to the load bearing behaviour can be predicted and reassessed with sufficient accuracy. Recent research achievements in the field of material science and the field of structural safety provide the means for the quantification of performance attributes as the safety and the serviceability of structures prior and during its design life. While the mentioned achievements are mainly applied for the design and maintenance of concrete and steel structures the knowledge about the behaviour of timber in structures is considered as partly not sufficient to provide the basis for design and maintenance frameworks of similar level of sophistication. Especially for maintenance and reassessment of existing timber structures the engineer is not equipped with codes and guidelines that facilitate proper decisions.
In the present presentation a theoretical framework for the inspection, reassessment and maintenance of existing timber structures is presented and possible applications in practice are discussed. Focus is also directed to existing procedures for the inspection and reassessment of timber structural elements.

State-of-the-art in in-situ evaluation of structural timber – some critical observations

Prof. Dr.-Ing. Bohumil Kasal
Director of the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut WKI, Braunschweig
Professor and Chair of Organic and Wood-Based Construction Materials, Technische Universität Braunschweig, Germany
Short Curriculum Vitae

In-situ assessment of structural timber is an important aspect of the evaluation of existing structures containing wood. Wood as a natural bio-material has a number of properties that need to be investigated both qualitatively and quantitatively. It appears that visual assessment, however subjective, plays a pivotal role in the investigation of in-situ timber and cannot be replaced. Various technologies have been used in determining wood properties, most of them indirect. Measurements of various physical quantities and subsequent inferences on material properties are contaminated by errors with various sources. The sources of these errors need to be considered when designing the investigation strategy and evaluating data.