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Richard M. Gutkowski - One of the best experts on this subject based on the ideXlab platform.

  • Repair of Full-Scale Timber Bridge Chord Members by Shear Spiking
    Journal of Bridge Engineering, 2008
    Co-Authors: Travis A. Burgers, Richard M. Gutkowski, Jeno Balogh, Donald W. Radford
    Abstract:

    The addition of vertically oriented shear spikes (fiberglass reinforced polymer rods) was shown to increase the effective stiffness of the stringers of a full-scale Timber Bridge chord specimen. Results found from the flexural load testing of a full-scale Timber Bridge chord laboratory specimen are presented. Reinforcement was provided with 19 mm diameter shear spikes bonded to the wood by an epoxy resin. The Bridge chord specimen was intentionally damaged to simulate degradation. Shear spikes were then installed from the top of the member into predrilled holes to provide horizontal shear resistance and to improve the flexural effective stiffness. Results from the testing showed that with the insertion of five sets of shear spikes the average flexural effective stiffness recovered in the four stringers of the chord was 91.6%.

  • field load tests of an anisotropic grid Timber Bridge
    Construction and Building Materials, 2008
    Co-Authors: Richard M. Gutkowski, Julius Natterer, P A Favre
    Abstract:

    Abstract This paper details the implementation of an innovative Timber Bridge technology developed for secondary road applications. A pilot Bridge was constructed and field tested under loads comparable to required design loads. A through-girder primary system with transverse floor beams and longitudinal wood deck secondary system are involved. A unique steel hanger system for suspending the transverse floor beams and providing I-beam action under lateral load was configured. Results of the field load test program and analytical predictions from a computer model are described. The pilot Bridge proved to be economically competitive and structurally effective.

  • laboratory tests of an anisotropic grid Timber Bridge
    Construction and Building Materials, 2007
    Co-Authors: Richard M. Gutkowski, P A Favre, Julius Natterer
    Abstract:

    Research and development was conducted on a prototype Timber Bridge technology developed for rural Bridge sites. The work included conception, computer modeling, laboratory load tests of a reduced size specimen, field construction of a pilot Bridge and field load testing. This paper describes the laboratory load test phase. Three loadings comprised of four concentrated loads simulating a truck wheel pattern were conducted. Results of preliminary analytical simulation work is also described. The laboratory specimen demonstrated the structural effectiveness of the concept and led to the final design and implementation of the pilot field Bridge. (c) 2005 Elsevier Ltd. All rights reserved.

  • Composite Repair of Full-Scale Timber Bridge Chord Members Through the Process of Shear Spiking
    2005
    Co-Authors: Travis A. Burgers, Richard M. Gutkowski, Donald W. Radford, Jeno Balogh
    Abstract:

    Investigations into the effects of the addition of vertically-oriented shear spikes with fiberglass reinforced polymer rods have shown that the shear spikes increased the effective stiffness of the stringers of a full-scale Timber Bridge chord specimen. This was previously found to be true on dimension lumber and medium-sized Timber. This report presents the results found from the flexural load testing of a full-scale Timber Bridge chord laboratory specimen. The Bridge chord specimen was intentionally damaged to simulate degradation. Reinforcement was provided with 19 mm (3/4-in.) diameter fiberglass reinforced polymer shear spikes bonded to the wood by an epoxy resin. Shear spikes were installed in pairs vertically from the top of the member into pre-drilled holes to provide horizontal shear resistance and to improve the flexural effective stiffness. Results from the testing showed that with the insertion of five sets of shear spikes an average effective stiffness of 91.6% was recovered in the four stringers of the chord.

  • Guardrail in Posttensioned Timber‐Bridge Specimen
    Journal of Structural Engineering-asce, 1994
    Co-Authors: Richard M. Gutkowski, P. J. Pellicane, Jean‐francois Kalin
    Abstract:

    A semiempirical, mathematical model for assessing the load behavior of Bridge guardrail systems is described. A full‐scale laboratory specimen was represented by a beam supported by coupled, elastic springs. Empirical flexibility coefficients were used to establish the spring constants for the post and deck subassembly of the specimen. This model was applied to a panelized, longitudinal‐deck Bridge specimen. Laboratory load tests were conducted both without and with posttensioning features incorporated into the specimen. Longitudinal, transverse and angular loads were separately applied to the specimen. The model was successful at predicting transverse load‐displacement behavior. A stiffening due to posttensioning was evident. Due to erratic load‐slip behavior of the connection details, the modeling of longitudinal load‐displacement behavior was unsuccessful. The danger of a possible failure of the guardrail post at a low load level was observed under longitudinal loading. Loosening of the post to deck co...

Hamid Saadatmanesh - One of the best experts on this subject based on the ideXlab platform.

  • strengthening Timber Bridge beams using carbon fiber
    Journal of Structural Engineering-asce, 2005
    Co-Authors: Ted W Buell, Hamid Saadatmanesh
    Abstract:

    This research project demonstrates how advanced composite materials can be used to strengthen existing Timber Bridge beams in order to increase the load capacity of the Bridge. Many times, the Timber Bridges were not designed to withstand the heavy truck traffic that they are currently carrying, and are therefore replaced in favor of modern concrete or steel Bridges. Current methods of strengthening Timber Bridges are not always practical or economical and so these Bridges are simply replaced at a high cost to the public. This project investigated whether applying composites in the form of either a fabric wrap or laminate strips to Timber beams would increase the load capacity of the beams. Bidirectional carbon fabric was the primary strengthening material used. A total of 10 solid-sawn Douglas Fir Timber beams were taken from a Timber stringer Bridge in Yuma, Ariz. that was replaced in 1999. Seven of the 10 creosote-treated beams were reinforced with carbon fiber and then tested for bending strength, shear strength, and stiffness. Three of the beams were tested as unreinforced control specimens. The results show that applying carbon fabric to the Timber beams provides significant increases in the bending and shear capacity, and nominal increases in the stiffness of the beams. Allowable stress modification factors are conceptually discussed that could potentially be used by engineers to determine the safe load-carrying capacity of beams reinforced with carbon fiber. However, a statistically significant number of Timber beams strengthened with carbon fiber need to be tested to arrive at definitive stress modification factors.

Michael A. Ritter - One of the best experts on this subject based on the ideXlab platform.

  • analysis of thermal change in stress laminated Timber Bridge decks
    2001
    Co-Authors: James A Kainz, James P. Wacker, Michael A. Ritter
    Abstract:

    As the Timber Bridge design has evolved, some engineers have been concerned about the integrity of the stress-laminated system in cold climates. The structural integrity of a stress-laminated Bridge depends on the level of interlaminar compression (between the wood laminations). Temperature change can cause material shrinkage, which could lead to substantial performance problems based on material mechanics and the nature of the stress-laminated system. In this study, to determine the effects of thermal change on interlaminar compression, four stress-laminated Timber deck sections were put through a warm-cold-warm cycle. Various interlaminar stress levels and three moisture content levels were tested. Results showed that interlaminar compression in stress-laminated decks of this size was not affected by extremely cold temperatures when the moisture content was less than 19% and when initial bar force was sufficient.

  • Timber Bridge initiatives in the United States
    Progress in Structural Engineering and Materials, 2000
    Co-Authors: Michael A. Ritter, Sheila Rimal Duwadi, Ed Cesa
    Abstract:

    Timber has been used for Bridge construction in the United States for hundreds of years. Despite the proven suitability of Timber for short- and medium- span Bridges, its use as a Bridge material has declined in the 20th century. This has been due in part to a lag in the development of new Timber Bridge technology compared to other materials, and an unfamiliarity with Timber on the part of many Bridge designers and contractors. Since 1988, two legislative acts have been passed by the US Congress to establish national programs aimed at improving Timber utilization in transportation structures. This paper briefly describes these Timber Bridge initiatives and summarizes activities in the areas of demonstration Bridges, research and development, and technology transfer.

  • Emerging Timber Bridge Technology in the United States
    1998
    Co-Authors: Michael A. Ritter
    Abstract:

    Timber has been successfully used as a Bridge material in the United States for hundreds of years. Historically, most Timber Bridges have been conventional beam or deck superstructures manufactured from softwood sawn lumber or glued laminated Timber. Since 1988, two legislative acts have been passed by the U.S. Congress to establish national programs aimed at improving Timber utilization in transportation structures. As a result, Timber Bridge research has increased, which is leading to significant technological advances. These advances have been well received, and many Bridges utilizing new technology have been constructed. This paper briefly describes selected emerging Timber Bridge technology in the United States related to Bridge materials, systems, and railings.

  • portable glulam Timber Bridge systems
    1997
    Co-Authors: S E Taylor, Michael A. Ritter, K P Keliher, J D Thompson
    Abstract:

    Recent interest in portable Bridge systems has increased due to a heightened awareness for reducing environmental impacts at road stream crossings. This paper discusses general design criteria for portable Timber Bridges and three case studies of portable longitudinal glued-laminated Timber (glulam) deck Bridges. Two of the Bridges use simple longitudinal glulam deck panels. The third Bridge uses two longitudinal glulam deck panels constructed in a unique double-tee cross section. AU three Bridges have performed well in service and appear to be cost effective when compared with the cost of installing traditional permanent stream crossings. In addition, they can be installed with minimal environmental impacts.

  • innovations in glulam Timber Bridge design
    Structures Congress XII, 1994
    Co-Authors: Michael A. Ritter, Thomas G. Williamson, Russell C Moody
    Abstract:

    Structural glued laminated Timber has been successfully used as a Bridge material in the United States for more than 50 years. Until the late 1980s, the majority of these Bridges were conventional girder or deck superstructures manufactured from softwood lumber species. Recently, applications employing glued laminated Timber have been expanded to include alternative wood species and new designs utilizing the concept of stress-laminating. Additionally, current research on the composite materials using glulam may lead to future applications for Timber Bridges. I n t r o d u c t i o n Structural glued laminated Timber (glulam) is an engineered, stress-rated product of a Timber-laminating plant. It consists of selected and prepared lumber laminations that are bonded together on their wide faces with structural adhesives. Glulam has been successfully used as a structural material in Europe since the late 1800s, In the United States, it has been used in buildings since approximately 1935 and in highway Bridges since the early 1940s. An important feature of glulam is that it is an 1 Research Engineer, U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI 53705. z Director, Engineered Wood Systems, American Plywood Association, 7011 So. 19th St., P.O. Box 11700, Tacoma, WA 98411 3 Project Leader, U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI 53705. This article was written and prepared by U.S. Government employees on official time, and it is therefore in the public domain and not subject to copyright.

Ted W Buell - One of the best experts on this subject based on the ideXlab platform.

  • strengthening Timber Bridge beams using carbon fiber
    Journal of Structural Engineering-asce, 2005
    Co-Authors: Ted W Buell, Hamid Saadatmanesh
    Abstract:

    This research project demonstrates how advanced composite materials can be used to strengthen existing Timber Bridge beams in order to increase the load capacity of the Bridge. Many times, the Timber Bridges were not designed to withstand the heavy truck traffic that they are currently carrying, and are therefore replaced in favor of modern concrete or steel Bridges. Current methods of strengthening Timber Bridges are not always practical or economical and so these Bridges are simply replaced at a high cost to the public. This project investigated whether applying composites in the form of either a fabric wrap or laminate strips to Timber beams would increase the load capacity of the beams. Bidirectional carbon fabric was the primary strengthening material used. A total of 10 solid-sawn Douglas Fir Timber beams were taken from a Timber stringer Bridge in Yuma, Ariz. that was replaced in 1999. Seven of the 10 creosote-treated beams were reinforced with carbon fiber and then tested for bending strength, shear strength, and stiffness. Three of the beams were tested as unreinforced control specimens. The results show that applying carbon fabric to the Timber beams provides significant increases in the bending and shear capacity, and nominal increases in the stiffness of the beams. Allowable stress modification factors are conceptually discussed that could potentially be used by engineers to determine the safe load-carrying capacity of beams reinforced with carbon fiber. However, a statistically significant number of Timber beams strengthened with carbon fiber need to be tested to arrive at definitive stress modification factors.

Hota V S Gangarao - One of the best experts on this subject based on the ideXlab platform.

  • nde of frp wrapped Timber Bridge components using infrared thermography
    REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION:Volume 22, 2003
    Co-Authors: U B Halabe, Hota V S Gangarao, W E Steele, P Klinkhachorn
    Abstract:

    This paper presents the results of an experimental study on the use of infrared thermography technique for detection of subsurface debonds in fiber reinforced polymer (FRP) wrapped Timber railroad Bridge components. Simulated subsurface debonds were constructed in the laboratory in Timber piles wrapped with FRP composite fabric. The debonds varied in size, thickness and severity. These debonds were placed between the 1/8″ thick FRP wrap and the Timber surface. The thermal images from the delaminated specimens were compared with the thermal images from undamaged specimens to study the effect of subsurface debonds. In addition, several field tests were conducted using the infrared imaging system on three Timber railroad Bridges located in Moorefield, West Virginia that were rehabilitated with FRP composite fabric wraps. The field test data was used to detect any possible debond at the composite‐Timber interface and study the effect of environmental parameters on the infrared images. This study showed that t...

  • Experimental evaluation of stressed Timber Bridge systems : Modern Timber Bridges
    Transportation Research Record, 1994
    Co-Authors: L S Barger, Roberto Lopez-anido, Hota V S Gangarao
    Abstract:

    The stiffness and transverse load distribution variations of stressed Timber Bridge system, including the shear lag phenomenon for the Tee and Box superstructure configurations, two stringer spacings, and two prestress levels, were examined. The tests were carried out for static loads that were applied at midspan on both interior and exterior stringer locations. Deflections and strains at different transverse locations on the deck and stringers were obtained. the analysis of the data provides helpful information to evaluate stiffnesses of stressed Tee and box Timber Bridges. Composite moments of inertia of the stringers were obtained from the experimental flexibility coefficients. Shear lag in flanges was evaluated by accounting for the effective flange width of an individual composite beam. The experimental strain variations were used to validate this model.

  • experimental evaluation of stressed Timber Bridge systems
    Transportation Research Record, 1993
    Co-Authors: L S Barger, Roberto Lopezanido, Hota V S Gangarao
    Abstract:

    The stiffness and transverse load distribution variations of stressed Timber Bridge systems, including the shear lag phenomenon for the Tee and Box superstructure configurations, two stringer spacings, and two prestress levels, were examined. The tests were carried out for static loads that were applied at midspan on both interior and exterior stringer locations. Deflections and strains at different transverse locations on the deck and stringers were obtained. The analysis of the data provides helpful information to evaluate stiffnesses of stressed Tee and Box Timber Bridges. Composite moments of inertia of the stringers were obtained from the experimental flexibility coefficients. Shear lag in flanges was evaluated by accounting for the effective flange width of an individual composite beam. The experimental strain variations were used to validate this model.