National Academies Press: OpenBook

Guidelines for Shielding Bridge Piers (2018)

Chapter: Chapter 7 - Conclusion

« Previous: Chapter 6 - Implementation Strategy
Page 92
Suggested Citation:"Chapter 7 - Conclusion." National Academies of Sciences, Engineering, and Medicine. 2018. Guidelines for Shielding Bridge Piers. Washington, DC: The National Academies Press. doi: 10.17226/25313.
×
Page 92

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

92 Conclusion The preceding chapters have presented bridge pier protec- tion guidelines proposed for inclusion in both the AASHTO LRFD Bridge Design Specifications and the RDG. Procedures, background regarding the development of those procedures, example problems, and comparisons to RSAPv3 have been presented. In the LRFD Bridge Design pier protection procedures, the user proceeds by looking up site-specific values in four tables and then inserting these values into a short calculation to determine the annual frequency of bridge collapse. If that value is less than 0.001 for a typical bridge or 0.0001 for a critical bridge, the pier system need not be shielded. These acceptance criteria values can be modified by AASHTO or adopting states should they want to make the criteria either more or less conservative. The proposed LRFD pier protection guidelines describe what types of pier systems need to be evaluated for shielding and also provide lateral capacity suggestions. If a shielding barrier is required, it must be a MASH crash-tested TL-5 rigid concrete barrier positioned on the site according to RDG Section 5.6.4. Additionally, a minimum 60-ft TL-5 rigid con- crete barrier should be provided in advance of the leading pier component. Reference has been made to the RDG to ensure conflict between publications is not created. The 60-ft minimum is suggested to ensure that, regardless of how the length-of-need calculations are presented in the RDG in the future, the LRFD will include the minimum barrier necessary to redirect a heavy vehicle. Similarly, for the passenger-vehicle occupant protection procedures, the user proceeds by looking up site-specific val- ues in three tables, then uses those values in a short calculation to determine the annual number of severe and fatal injury crashes. If that value is less than 0.0001 severe or fatal injury crashes per year, then the pier system need not be shielded for occupant protection. These criteria can be modified by AASHTO or adopting states should they want to make the criteria either more or less conservative. If a shielding bar- rier is required for passenger-vehicle occupant protection, a MASH crash-tested TL-3 w-beam guardrail positioned on the site according to RDG Section 5.6.4 is suggested. Four example problems were presented that illustrate the application of both the LRFD and RDG procedures and com- pare the results to RSAPv3 simulations. The results of the pro- cedures compare closely with the RSAPv3 estimates. C H A P T E R 7

Next: References »
Guidelines for Shielding Bridge Piers Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

TRB’s National Cooperative Highway Research Program (NCHRP) Research Report 892: Guidelines for Shielding Bridge Piers provides proposed load and resistance factor design (LRFD) bridge design pier protection specifications and proposed occupant protection guidelines. Bridge piers are generally close to the roadway to minimize bridge lengths. As a consequence, barriers are normally placed around piers to reduce the potential of vehicle crashes damaging the piers. However, the design and placement of the barriers may not have taken into consideration the possibility that vehicles, particularly large trucks, might still impact the pier. The report also includes four examples that illustrate the use of the proposed specifications and guidelines for shielding bridge piers.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!