Source: NORTH CAROLINA STATE UNIV submitted to
IN-SITU EVALUATION OF WOOD STRUCTURAL MEMBERS AND BUILDINGS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
MCINTIRE-STENNIS
Reporting Frequency
Annual
Accession No.
0195500
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Jul 1, 2003
Project End Date
Dec 31, 2003
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
NORTH CAROLINA STATE UNIV
(N/A)
RALEIGH,NC 27695
Performing Department
WOOD AND PAPER SCIENCE
Non Technical Summary
Wood in service has been subject to various degrees of deterioration and the evaluation of wood in service is crucial for making decisions impacting efficent use of wood in new and historic construction. The goal of this proposal is to develop a systematic way of evaluating historic and current timber structures such that mechanical properties (strength and modulus of elasticity) and condition of the members can be determined with increased confidence over traditional methods.
Animal Health Component
80%
Research Effort Categories
Basic
20%
Applied
80%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
51106502020100%
Knowledge Area
511 - New and Improved Non-Food Products and Processes;

Subject Of Investigation
0650 - Wood and wood products;

Field Of Science
2020 - Engineering;
Goals / Objectives
The goal of this proposal is to develop a systematic way of evaluating historic timber structures such that mechanical properties (strength and modulus of elasticity) and condition of the members can be determined with increased confidence over traditional methods. The goal will be achieved through the following specific objectives: 1. Development of semi-destructive testing methods allowing direct measurement of mechanical and physical properties. The methods will focus on the mechanical core drilling technique combined with compressive test of cylindrical micro-specimens, resistance drilling and digital radioscopy. 2. Development of a methodology to evaluate timber structures based on a combination of classical nondestructive methods, semi-destructive methods and statistical data analysis and simulation. 3. Verification of the developed methods and methodology through laboratory experiments and field studies.
Project Methods
To achieve the goals of this proposal, the following research plan is proposed: Core drill method: 1. Development of the core drills suitable for field applications to remove undesirable unstable cutting path. 2. Development of a relationship between small core compressive strength and deformation characteristics and ASTM (ASTM 2000) small clear specimen tests. This information will be further used to establish allowable design values for in-situ structural members. Digital Radioscopy: Logistical work will include a review of the use of film and real-time x-ray technology for investigation of buildings and materials. Laboratory work will consist of construction of mock-ups using a variety of wood and masonry configurations that represent common construction in historic structures. The purpose of this task is to begin to determine the capabilities and limitations of real-time x-ray. This task will aid in determining the capabilities and limitations of the digital radioscopy to penetrate various constructions and provide meaningful data. For the first time, using digital radioscopy, it may be possible to view construction details in three dimensions. Condition assessment of connections, including corroded or missing fasteners is a key limitation to structural assessment today for historic and recent buildings. This research will provide significant advances for the condition assessment of connections. Sections of wood with various modes of deterioration will be examined to determine the applicability of digital radioscopy for this critical need for structural assessment. Decay, termites and mechanical damage in timber is often difficult to assess without extensive destructive tests. This research will determine the applicability of digital radioscopy for assessing internal deterioration in wood. In-situ and laboratory experiments: The test methods developed above will be tested at in-situ conditions. Several historic buildings will be identified and member properties will be measured. One building will be selected based on known construction or defects for the purpose of verifying the results from the laboratory study. The other buildings will be selected based on having unknown conditions, or challenging inspection and assessment needs. This may include the possibility of internal deterioration of timber due to decay or insect damage, unknown masonry wall construction or unknown connection details. Development of a hybrid method that includes a combination of indirect NDT methods and semi-destructive method. A combination of the following methods is proposed: 1. Stress wave method to locate global properties 2. Digital radioscopy to investigate internal structure 3. Core drill method to evaluate compressive strength, modulus of elasticity, density and moisture content. This method is used to evaluate characteristics of healthy wood. 4. Resistance drilling to investigate possible defects identified by methods 1 and 2

Progress 01/01/03 to 12/31/03

Outputs
Laboratory tests of microspecimen techniques were performed. Low-energy portable x-ray system was, for the first time, tested in the laboratory to investigate internal defects and connections of timber structural members. The microspecimen technique and low-energy x-ray technique were used in the in-situ pilot project. The data evaluation from the in-situ tests was done and practical applications were demonstrated. The results were published in the international journals.

Impacts
Impoved methods for assesment of in-situ wood structural members.

Publications

  • Kasal, B., and R. Anthony. 2004. Advances in in situ evaluation of timber structures. Progress in Structural Engineering. John Villey & Sons Ltd. London. UK. (invited contribution, in print).
  • Kasal, B. 2004. Mechanical properties of wood. Encyclopedia of Forest Science. Elsevier Publishing Co., Oxford, England. ISBN 0121451207. 2000 p. Book Chapter.
  • Kasal, B. 2003. Semi-destructive method for in-situ evaluation of compressive strength of wood structural members. Forest Product Journal. 53 (11/12): 55-87.
  • Kasal, B, M. Drdacky, I. Jirovsky. 2003. Semi-destructive methods for evaluation of timber structures. Structural Studies, Repairs and Maintenance of Heritage Architecture VIII. C.A. Brebia, Editor. Advances in Architecture. WIT Press. Southampton. ISBN 1-85312-968-2: 835-842
  • Anthony, R., M. Drdacky, I. Jirovsky, and B. Kasal. 2003. X-ray diagnostics of historic timber structures [in Czech]. In Proceedings of the Historic structures conference. High Tatras, Slovakia.