Treesearch

The Little Salmon Creek bridge was constructed in November 1988 on the Allegheny National Forest in Pennsylvania. The bridge is a simple span, single-lane, stress-laminated deck superstructure that is approximately 26-ft long and 16-ft wide. The bridge is unique in that it is the first known stress-laminated timber bridge to be constructed of hardwood lumber. The performance of the bridge was monitored continuously for approximately 4 years, beginning at the time of installation. Performance monitoring involved gathering and evaluating data relative to the moisture content of the wood...

Forest Service, Bureau of Land Management, and industry partners are cooperating in a study of the leaching and environmental effects of a wetland boardwalk. The construction project is considered bworst casec because the site has high rainfall and large volumes of treated wood were used. Separate boardwalk test sections were constructed using untreated wood or wood treated with ammoniacal copper quat Type B (ACQ1B), ammoniacal copper zinc arsenate (ACZA), chromated copper arsenate Type C (CCA1C), or copper dimethyldithiocarbamate (CDDC). Part I of this report focuses on leaching of...

The Pueblo County 204B bridge was constructed in March 1990 in Pueblo, Colorado, as a demonstration bridge under the USDA Forest Service Timber Bridge Initiative. The stress-laminated deck superstructure is approximately 10 m long, 9 m wide, and 406 mm deep, with a skew of 10 degrees. Performance monitoring was conducted for 3 years, beginning at installation, and involved gathering data on the moisture content of the wood deck, the force level of the stressing bars, the behavior of the bridge under static load conditions, and the overall condition of the structure. In addition, long-term...

For maximum protection against wood decay and termites, use posts that have an in-depth preservative treatment, preferably a pressure treatment for below ground use. When selecting posts of naturally decay-resistant woods, choose posts with mostly heartwood. Horizontal rails require more protection from decay than do vertical boards. In regions of high and moderate decay hazard, build rails with naturally decay-resistant wood or with pressure-treated wood . Boards, pickets and other face parts should be of decay-resistant wood (either natural or treated) in areas where high decay is...

The primary benefit of this research was to lay a foundation for examining and predicting future participation in recreation on a specific national forest. We explain some of the obstacles involved in site-specific projections and note that this is an area in need of additional research.This study used data from the 1990 U.S. Census to examine changes in the human population surrounding the Chequamegon and Nicolet National Forests in Wisconsin. A methodology was then developed to project future participation in recreation on those national forests based solely on demographics. This...

The Connell Lake bridge was constructed in early 1991 on the Tongass National Forest, Alaska, as a demonstration bridge under the Timber Bridge Initiative. The bridge is a stress-laminated deck structure with an approximate 36-ft length and 18-ft width and is the first known stress-laminated timber bridge constructed in Alaska. Performance of the bridge was monitored for 2-1/2 years, beginning at bridge construction. Performance monitoring involved gathering and evaluating data relative to the moisture content of the wood deck, the force level of the stressing bars, and the deflection...

In this study, we developed a simple equation to calculate average fiber stress values for design of glued-laminated (glulam) timber utility structures as a function of design bending stress. We took design stress in bending values specified by the American Institute of Timber Construction (AITC) for various combinations of glulam timber, applied appropriate end-use adjustments, and determined an appropriate factor to obtain average modulus of rupture. Fiber stresses for glulam were then determined from the average modulus of rupture values using the relationship between these values and...

In bridge applications, it is often necessary to minimize the depth of the bridge structure to provide for the required hydraulic opening or reduce the volume of approach fill. For bridges that utilize structural glued-laminated (glulam) timber beams as stringers, reinforcement using thin strips of pultruded E-glass-fiber-reinforced plastic (GFRP) composites may permit reduced depth, because the reinforcement has the potential to increase stiffness and strength. This study is part of an overall effort aimed at evaluating the potential for commercial production of glulam-GFRP beams in...

The Sanborn Brook bridge was constructed in August 1991, 10 miles northeast of Concord, New Hampshire, as part of the demonstration timber bridge program of the USDA Forest Service. The bridge is a simple-span, double-lane, stress-laminated deck superstructure constructed from Southern Pine lumber and is approximately 25 ft long and 28 ft wide with a skew of 14 degrees. The performance of the bridge was monitored continuously for approximately 2 years, beginning shortly after installation. Performance monitoring involved collecting and evaluating data pertaining to the moisture content of...

The Big Erickas bridge was constructed during September 1992 in Baraga County, Michigan. The bridge is 72 ft long, 16 ft wide, and consists of three simple spans: two stress-laminated deck approach spans and a stress-laminated box center span. The bridge is unique in that it is one of the first known stress-laminated timber bridge applications to use Eastern Hemlock sawn lumber and a combination of stress-laminated decks and a stress-laminated box in a single bridge. Performance of the bridge was monitored for 35 months, beginning at the time of installation. Monitoring involved gathering...