215-AST : In-situ assessment of structural timber

Technical Committee 215-AST

General Information

Chair: Prof. Dr. Ing. Bohumil KASAL
Deputy Chair: Dr Thomas TANNERT
Activity starting in: 2005
Activity ending in: 2012
Cluster E

Subject matter

The subjects are in-situ timber (wood, wood materials) structural members and evaluation of their material (physical and mechanical properties) characteristics. The physical properties include the species/species groups, size, orientations, age, moisture contents, density and level of deterioration. The mechanical properties entail strength and elasticity parameters. The target phenomena that will be studied include life expectancy, failure probability and durability of the structure under investigation. The investigations will include both experimental and theoretical studies. The experimental studies will include testing and validation of non-destructive (NDT) and semi-destructive (SDT) methods including case studies where these methods are applied. The theoretical studies will focus on reliability and robustness of the NDT, SDT and their combination. The ND techniques have been used in assessment of timber structures for some time, the SDT are relatively new techniques. New methods are under development and some of the proposed members listed below are actively working on these developments. No reliability assessments of any of these methods and their combinations have been done. The TC will focus on structural applications of timber and aspects such as quality control, product development, composite boards evaluation techniques (unless directly related to in-situ evaluation in structures) will be excluded.

Terms of reference

The objectives will be achieved by the following:
- Comprehensive literature review of the state-of-the art. Such literature review has been done by the TC proposer (see References) but it did not include the power-of-prediction analyses.
- The membership that will include leading experts in the field will permit close collaboration. It is expected that such collaboration will result in joint workshops, case studies and active participation in conferences. Collaboration between the industry, practitioners and academia is anticipated.
- Many of the proposed members have ongoing research program in the above area and the TC will facilitate stronger research coordination, eliminate duplication and permit faster application of the newly developed and improved NDT and SDT methods.
- It is anticipated that this TC, if established, may continue by means of new potential TCs because:
a. Wood structures are significant part of our cultural heritage and are subject to biodeterioration. The need for their preservation is eminent.
b. Wood is becoming increasingly more important structural material due to its environmental friendliness, renewability and economics. With the increased volume of timber being used in buildings and infrastructure, the need for reliable in-situ evaluation methods will grow.

Detailed working programme

The working program will include the following:
- Initial committee meeting (Summer/Fall 2005, Raleigh, NC, USA), Responsible: Kasal (or Prague, responsible Drdácky)
- Comprehensive state-of-the-art paper and workshop dealing with the reliability and predictive power of existing NDT and SDT methods. (2006). Responsible: TBD (to be determined at the TC initial meeting).
- Experimental studies of new and improved NDT and SDT methods applicable to wood that will include rapid chemical analyses, dendrochronology, radiography, ultrasound and stress-wave methods, core and resistance drillings and other applicable methods. Responsible: TBD 2005-2008. In 2008 a summarizing workshop. Every year a demonstration and training course.
- Development of international evaluation protocol and set of guidelines for in-situ evaluation of timber structural members. Responsible: TBD. 2008-2009

The expected timeframe for the above goals is 5 years. Yearly evaluation of each milestone will take place at the TC annual meetings. The individual subtasks will be established at the initial TC meeting planned in Raleigh, NC, USA (or Prague, Czech Republic).

Technical environment

The NDT’s are used in other materials such as reinforced concrete, masonry or mortars. Some of the techniques are equally applicable to several materials while others are material specific. Close collaboration between the pertinent TC’s is essential and the TC will invite representatives of the corresponding TC to all its meetings. Likewise, active participation of the designated TC members in the activities of other RILEM TC’s dealing with the NDD is anticipated. The TC will collaborate with the following organizations (members of the TC are also the members of the listed entities): American Society of Civil Engineers (ASCE), American Society of Experimental Mechanics, Forest Products Society, American Academy of Mechanics, Institute of Structural Engineers.

Expected achievements

The expected achievements are as follows:
- International collaboration in in-situ investigation of wood structures. The TC will create a basis for exchange of ideas, research data, and new collaborations.
- Harmonised test recommendation for the individual methods will be developed and proposed.
- Database of case studies will be created.
- Relevant publications reflecting the most recent state-of-the art developments will be written.
- The TC will organize at least two international workshops and will organize special session on the in-situ evaluation of wood structures at the World Conference in Timber Engineering held in Portland, OR in 2006 and ASCE Structures Congress.
- The TC will attempt to develop international collaborative research proposals that will be submitted to the European Community FP 6 and 7 program, National Science Foundation (US) and other national funding agencies.
- The TC will involve young investigators and students through individual research programs.

Group of users

It is anticipated the professionals active in testing, restoration, rehabilitation and evaluation of timber structures will directly benefit from the proposed activities through:
a. workshops organized by the TC
b. availability of the literature produced by the TC (items 6.2 –6.7 above)

Specific use of the results

The results will have impact on:
- evaluation of historic structures and decision-making process in their restoration. It is anticipated that the TC work will lead to better and more comprehensive in-situ evaluation of existing wood structural members and structures.
This has profound effect on costs of restoration and rehabilitation of historic buildings especially, however, the results are widely applicable in rehabilitation of built environment generally;
- assessment of durability of existing structures such as bridges. The potential economic impact lies in more precise and reliable evaluation of the existing infrastructure that will increase public safety and preserve resources through timely interventions.