MPC
Research Projects (2006-07)

Identifying Number

MPC-276

Project Title

Use of Salvaged Utility Poles in Roadway Bridges, Year 1

University

Colorado State University

Project Investigator:

Richard Gutkowski, CSU
gutkowsk@engr.colostate.edu

External Project Contact

N/A

Project Objective

The objective of this project is to configure and construct a medium span roadway bridge in the laboratory using an innovative composite concrete-wood concept and test it under ramp loading, repeated loading and creep loading.

Project Abstract

Frequently, wood utility poles are replaced as part of secondary road reconstruction, such as widening roadways. Many of the removed poles are still sound structurally and useable. Instead of discarding these members, it is worthwhile to consider viable alternative uses. Since utility poles are commonly 40-60 ft long, they can be a low cost resource for medium span bridge construction. Conceiving such uses in which the existing poles are used enables a large supply of poles to be re-used. Indeed, the PI readily accomplished a donation of the utility poles from the utility company for use in this project, suggesting a possible future low cost or no cost material source. This project involves conceiving and configuring a composite bridge comprised of concrete and utility poles. The concept is to use utility poles as either stringers or a solid deck beneath a conventional reinforced concrete bridge deck.

Task Descriptions

The tapered utility poles will be placed in alternating directions at a slight incline to incorporate camber, and topped with a structural concrete layer. A notched shear key/anchor interconnection will be examined as a means of compositely connecting the concrete to the wood members. This detail has been examined in past CSU research, but alternatives exist in recent literature by other researchers. A literature review will be conducted to assess the most favorable structural and cost-effective approach for interconnection. Computer-based structural modeling will be employed to configure the bridge and predict camber required. In Year 1, a set of low cost wide beams made of this construction will be used to troubleshoot the concept. If successful, in Year 2, an extension to either a w/c deck or stringer bridge construction and similar load tests will be proposed for consideration for further funding.

Milestones, Dates

Starting Date: July 1, 2006
Ending Date: June 30, 2007

Yearly and Total Budget

$54,585

Student Involvement

Two graduate students; one undergraduate student

Relationship to Other Research Projects

The approach being investigated is adapted from prior MPC supported work on short span bridges made of a composite wood-concrete (w/c) deck bridge system, in which a concrete deck layer is interconnected to a wood deck of solid sawn lumber. Prior laboratory results show this to be effective for initial stresses and short term absolute deflection for short span systems. A present project is examining a novel cambering technique and long term creep effects with promising results for somewhat longer spans.

Technology Transfer Activities

An innovative bridge concept will be configured. An MPC report and TLN videoconference seminar is planned for dissemination of the results. A potential pilot field bridge construction is being explored, with timing envisioned after this project.

Potential Benefits of the Project

Much of rural America has low tax base communities dependent on the agricultural economies and related freight and shipping industry. Developing low cost, easily constructed bridge systems for short to medium span situations on secondary roads is helpful. Examples of recently constructed layered w/c bridges using road poles exist in Europe. Also, a 55 foot span w/c stringer bridge was built with glue-laminated wood beams in Portugal. The PI has visited that bridge site and discussed its construction with the research team. Coincidentally, they will be visiting CSU in August 2006 and can provide advice regarding this project. These successful overseas examples lend credibility to the above concept as being practically plausible.

TRB Keywords

Bridges, Composite, Concrete, Wood, Salvaged Utility Poles