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Project Details
STATUS

In-Progress

START DATE

07/11/11

END DATE

01/31/15

RESEARCH CENTERS InTrans, BEC, CTRE
SPONSORS

USDA Forest Service

Researchers
Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

Development of data processing techniques for determining changes in structural stiffness of timber bridges

Project Details
STATUS

In-Progress

START DATE

06/26/14

END DATE

06/15/18

RESEARCH CENTERS InTrans, BEC, CTRE, NCWTS
SPONSORS

USDA Forest Service

Researchers
Principal Investigator
Travis Hosteng

Co-Director, NCWTS

Co-Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

Timber bridge with geosynthetic-reinforced soil (GRS) abutments in Buchanan County.

Project Details
STATUS

Completed

START DATE

08/08/06

END DATE

12/31/10

RESEARCH CENTERS InTrans, BEC, CTRE
SPONSORS

USDA Forest Service

Researchers
Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

Co-Principal Investigator
Terry Wipf

Faculty Affiliate

About the research

To implement concepts developed separately that are related to the development of a smart timber bridge that has capabilities to automatically report on changes in its condition.

Project Details
STATUS

Completed

START DATE

04/24/06

END DATE

05/31/08

RESEARCH CENTERS InTrans, BEC, CTRE
SPONSORS

USDA Forest Service

Researchers
Principal Investigator
Sri Sritharan

Faculty Affiliate

About the research

The objective of this research is to reduce, evaluate, and analyze wind loading data collected during Hurricane Katrina and to perform finite element modeling of the structure from which the data were collected in order to better understand the behavior of structures under wind loadings and to understand the wind-structure interaction.

Project Details
STATUS

Completed

START DATE

07/01/04

END DATE

09/30/05

RESEARCH CENTERS InTrans, CTRE
SPONSORS

USDA Forest Service

Researchers
Co-Principal Investigator
Terry Wipf

Faculty Affiliate

Co-Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

This work will develop design recommendations to minimize differential deck panel deflection, which has been shown to be one source of deterioration of asphalt wearing surfaces on these panels. In addition, this research will seek out a bridge owner with a bridge with a history of differential panel deflection induced deterioration. The research team will work with the bridge owner to implement a repair/rehabilitation scheme.

Project Details
STATUS

Completed

START DATE

01/01/02

END DATE

12/31/04

RESEARCH CENTERS InTrans, BEC, CTRE
SPONSORS

USDA Forest Service

Researchers
Principal Investigator
Terry Wipf

Faculty Affiliate

Co-Principal Investigator
Doug Wood

Senior Engineering Specialist, BEC

Co-Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

The objective of this project was to evaluate the effectiveness and usefulness of using glued laminated (glulam) timber stringers as helper stringers to add strength and stiffness to an existing timber railroad bridge. The scope includes loading the bridge and measuring deflection of the bridge both before and after the addition of the glulam stringers to determine the percent increase in stiffness caused by the helper stringers, as well as, their effect on load sharing between individual stringers.

The test bridge is located on a Pudget Sound and Pacific Railroad Co. (PSP) rail line between Centralia and Elma, Washington. This rail line serves the PSP headquarters in Elma via Centralia, and southern Washington running parallel to State Highway 12. The bridge is an eight span, 114 ft. 6 in., continuous timber bridge crossing Gibson Creek at milepost 38.8.

Project features include documenting the installation of the helper stringers and testing the bridge, under known loads, to determine the effectiveness of the helper stringers.

Project Details
STATUS

Completed

START DATE

01/01/02

END DATE

12/31/04

RESEARCH CENTERS InTrans, BEC, CTRE
SPONSORS

USDA Forest Service

Researchers
Principal Investigator
Terry Wipf

Faculty Affiliate

Co-Principal Investigator
Doug Wood

Senior Engineering Specialist, BEC

Co-Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

Student Researcher(s)
Travis Hosteng

About the research

Deflection criteria typically used in the design of highway bridges are currently based on arbitrary limits. Although the need for having deflection limits is undisputed, there exists a need for live load defection criteria for timber superstructures and decks based on actual structural behavior, performance of wearing surfaces, and user perception. In addition, current deflection limits are based solely on total deflection. However, past experience has shown that differential deflection may be a more important parameter. As a result, a need exists for research related to the importance of and allowable limits for differential deflections as they relate to the long-term performance of timber bridges.

Project features include the following: 1)Completion of a survey of state and local bridge owners on the use of live load deflection criteria. 2) Field testing and in-depth condition assessment of 20-30 timber bridges with varying superstructure and deck types. 3)Analytical modeling and extrapolation of timber bridges for a sensitivity analysis. 4) Development of deflection criteria (e.g., total, differential) based on results of field testing and analytical modeling.

Project Details
STATUS

Completed

START DATE

06/01/00

END DATE

11/01/01

RESEARCH CENTERS InTrans, BEC
SPONSORS

Federal Highway Administration
USDA Forest Service

Researchers
Principal Investigator
Terry Wipf

Faculty Affiliate

About the research

Iowa State University (ISU) and the Forest Products Laboratory (FPL) at Madison, Wisconsin have done extensive load testing of timber bridges around the country to study the behavior of timber bridges and improve upon the existing design methodologies for various types of timber bridges. As part of this study effective analysis tools were developed to aid with bridge evaluation of stress-laminated deck, longitudinal deck, and glued laminated girder bridges. Sensitivity evaluations were performed on numerous field bridges that had been previously load tested. The study developed modeling recommendations and computer programs for the analysis and evaluation of both skew and non-skew bridges. The finite element model software developed includes pre- and post-processors for ANSYS. A sensitivity analysis was also performed to determine a reasonable element size and aspect ratio to model the deck elements. These programs were written in ANSYS Parametric Design Language that is available in ANSYS finite element analysis commercial software. The programs require limited input like bridge dimensions, material properties, load, and load positions for analyzing the bridge. The output file contains deflection and stress results at desired cross-sections of the bridge. This output can be imported into the Excel software to represent the results in a graphical manner.

Project Details
STATUS

Completed

START DATE

09/01/92

END DATE

11/01/95

RESEARCH CENTERS InTrans, BEC
SPONSORS

Federal Highway Administration
USDA Forest Service

Researchers
Principal Investigator
Doug Wood

Senior Engineering Specialist, BEC

Principal Investigator
Terry Wipf

Faculty Affiliate

About the research

To account for the dynamic loads imposed by passing vehicles, the Standard Specifications for Highway Bridges of the American Association of State Highway and Transportation Officials (AASHTO) prescribes that dynamic allowance be applied. Historically AASHTO has not contained a provision for dynamic allowance for wood bridges. Recently, the exclusion of wood bridges from dynamic allowance requirements has been questioned. This issue was doubly important given the recent major revisions to the specification. Recent studies have shown that the dynamic allowance can account for a significant portion of the total response and thus should be considered. The objective of the research was to determine the dynamic performance characteristics of timber bridges, including stress-laminated deck, longitudinal deck and glued laminated stringer bridges. A matrix of field bridges of each type was identified and field load tests were performed. Both bridge deflection and acceleration data were collected during the load testing. In addition, test truck acceleration data were also collected. An analytical study was performed to further study the bridges? dynamic performance and design recommendations were developed for inclusion into the AASHTO Standard Specification for Highway Bridges.

Project Details
STATUS

Completed

START DATE

06/01/91

END DATE

06/01/92

RESEARCH CENTERS InTrans, BEC
SPONSORS

Federal Highway Administration
USDA Forest Service

Researchers
Principal Investigator
Terry Wipf

Faculty Affiliate

About the research

This study was completed in 1993 to identify, describe, and prioritize a list of research needs that served as a basis for developing and funding research including cooperative research with universities and other organizations. A report was published after completion of the study that entitled “Research Accomplishments for Wood Transportation Structures Based on a National Research Needs Assessment.” The report summarized the research accomplishments related to the priorities identified in the research needs study completed in 1993. The research needs and the associated accomplishments in the report are listed in the following areas: Area I: System Development and Design Area II: Lumber Design Properties Area III: Preservatives Area IV: Alternative Transportation System Structures Area V: Inspection and Rehabilitation Area VI: Technology and Information Transfer Area VII: Other Area VIII: Additional Projects

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