Dr. Ronald K. Faller
Date of this Version
Duren, J.T., Prioritization of Research on Bridge Railings for Use on Timber Deck Bridges and Development of Two Glulam Bridge Railing Systems, Thesis, University of Nebraska-Lincoln, July 2021.
In the past, many timber bridge railings, bridge railings for use on timber deck bridges, and approach guardrail transition systems to accompany these railings, have been developed to meet different impact safety criteria. Through an extensive literature review, the design details of these systems were identified and organized. A survey was then developed and distributed to multiple government agencies and timber industry members to identify their desire for these bridge railing and approach guardrail transition systems to be developed to meet current American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) impact safety criteria. The data provided from the survey was analyzed, and a list of 15 bridge railing systems was created, which included accompanying approach guardrail transitions. This list prioritized the bridge railing systems based upon the number of survey respondents requesting such a bridge railing system. Cost estimates for the research and development of each bridge railing system were also provided in order to proceed into subsequent phases of this research project.
The development of a MASH TL-4 glued-laminated (glulam) timber rail with curb bridge railing system was initiated in Phase II. Many similar systems have been developed in the past to meet previous impact safety criteria, but an updated design was necessary to meet current MASH impact safety criteria. Through impact simulations with the computer software program BARRIER VII, a model was created and calibrated to previous crash testing results. After a series of modifications to the bridge railing system represented in the model, including increasing the size and height of multiple components, the simulation effort demonstrated that the modified TL-4 bridge railing was acceptable under the MASH criteria. Additional research on connection details and timber deck strengths, the development of an approach guardrail transition system, and component and full-scale testing programs are yet to be performed in the completion of the Phase II project.
An additional project was advanced and involved the adaptation of a previously-developed, MASH TL-1 crashworthy, low-height, curb-type, glulam bridge railing system for transverse, nail-laminated decks to be capable of use on transverse, glulam timber decks, which is part of a Phase III effort. Analysis of the system components and timber deck types led to the creation of a static and dynamic component testing program utilizing two surrogate bridge decks. To date, the test plans and details have been developed, with the construction and testing programs yet to be performed. In the future, results from the component testing program will be utilized to demonstrate that the bridge railing system contains adequate height and strength when used on transverse, glulam timber decks.
Advisor: Ronald K. Faller