Date of Graduation

12-2025

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Heymsfield, Ernie

Committee Member

Murray, Cameron

Second Committee Member

Hale, Micah

Keywords

Bridge; Moisture content; Timber; Wood

Abstract

Reducing moisture content increases wood strength and reduces the weight of timber members. An accurate and efficient method for measuring moisture content is important for the design and construction of indigenous timber short-gap crossings. This study evaluates different methods for measuring moisture content in timber, describes a methodology for developing a representative moisture content value for a timber log, and approaches for quickly drying large timber logs. The results of this thesis will support activities in developing a representative moisture content of a log for structural design purposes and reducing weight for constructability purposes. The approaches discussed were developed considering a theatre of war scenario when material resources and labor are limited and construction speed and efficiency are essential. Several moisture content measurement methods were explored. Ultimately, the Lignomat K2-M electrical resistance-based moisture meter was selected due to its ease of use and the device’s ability to measure wood penetration depths of up to 7 in, without compromising the structural integrity of the wood test specimen. Due to the variability of moisture content in wood, a representative moisture content value for a large timber log was estimated by averaging moisture content values taken every 3-5 ft. along a member. Reducing moisture content using a custom, kiln-like heat chamber is the most viable option for rapidly drying large timber members under the given theatre of war restraints. A heat chamber was designed and built during the study. The heat chamber is a 4 ft. x 4 ft. x 20 ft. wood-framed sheet metal box. A diesel space heater is used for heating. Tests showed drying performance depended on timber size, ambient temperature, and heating duration. Rapid drying at high temperatures produced cracking and bowing. Structural testing of members dried to below the fiber saturation point showed increased stiffness and strength while decreasing weight.

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