Dynamic Load Allowance Provisions for Box Culverts with Low Fill Depth
- 92 Downloads
It is well established that vehicular traffic traveling over bridge-like structures can impart a dynamic load effect that is greater than vehicles’ static weight alone. In order to account for this increased load, bridge design codes use a factor known as the dynamic load allowance (IM) to amplify static vehicular live loads. In the current version of the American Association of State Highway and Transportation Officials (AASHTO) Manual for Bridge Evaluation (MBE), reductions in IM are allowed for bridges having span lengths greater than 12.2 m with road surfaces in good condition. In addition, the current AASHTO LRFD Bridge Design Specifications allow for a reduced IM for culverts with higher fill depth. However, many culverts have neither span lengths greater than 12.2 m nor higher fill depths and thus are not eligible for such IM reductions. This paper investigated whether similar IM reductions can be considered for culverts with smaller span lengths and fill depths. The field experiments conducted suggest that culverts having span lengths less than 12.2 m and fill depths less than 0.5 m could be considered for similar IM reductions allowed by the MBE.
KeywordsDynamic load allowance Load amplification Buried culverts Load rating Fill depth
The authors of this paper gratefully acknowledge the support of the Delaware Department of Transportation.
Compliance with Ethical Standards
Any opinions, findings, and conclusions or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the Delaware Department of Transportation.
- 1.AASHO: The AASHO road test. Report 4, Highway Research Board, Special Report 61D, Washington, D.C. (1962)Google Scholar
- 2.AASHTO: Manual for Bridge Evaluation, 2nd Edition, with 2011, 2013, 2014, 2015 and 2016 Interim Revisions. American Association of State Highway and Transportation Officials, Washington (2011)Google Scholar
- 3.AASHTO: LRFD Bridge Design Specifications, 6th Edition, with 2012 and 2013 Interim Revisions. American Association of State Highway and Transportation Officials, Washington (2012)Google Scholar
- 6.Cantieni, R.: Dynamic load testing of highway bridges. Second bridge engineering conference, pp. 141–148. Transportation Research Board, Minneapolis (1984)Google Scholar
- 8.Csagoly, P.F., Campbell, T.I., Agarwal, A.C.: Bridge vibration study. Downsview, Ontario (1972)Google Scholar
- 9.FHWA: Recording and Coding Guide for the Structure Inventory and Appraisal of the nation’s Bridges. United States Department of Transportation, Washington, DC (1995)Google Scholar
- 12.McLean, D.L., Marsh, M.L.: Dynamic amplification factors for bridges. Synthesis of Highway Practice 266. Transportation Research Board, Washington (1998)Google Scholar
- 13.Nowak, A.S.: Calibration of LRFD bridge design code. NCHRP Report 368. Transportation Research Board, Washington (1999)Google Scholar
- 15.Spangler, M.G., Mason, C., Winfrey, R.E.: Experimental Determinations of Static and Impact Loads Transmitted to Culverts. Iowa State College, Ames (1926)Google Scholar
- 16.Tilly, G.P.: Dynamic Behaviour of Concrete Structures: Report of the RILEM 65 MDB Committee. Elsevier, Amsterdam (1986)Google Scholar
- 17.Wekezer, J., Taft, E., Kwasniewski, L., Earle, S.: Investigation of impact factors for FDOT bridges. Tallahassee, Florida (2010)Google Scholar
- 18.Wells, A.: Analytical and experimental investigation of dynamic amplification factor for the load rating of reinforced concrete box culverts. Master of Civil Engineering Thesis, University of Delaware (2016)Google Scholar