Investigation of Natural Frequency for Continuous Steel Bridges with Variable Cross-sections by using Finite Element Method

Abstract

This paper mainly focuses on the natural frequencies of steel I-girder continuous-span bridges with straight haunched sections. The finite element analysis is performed to model dynamic behaviour of bridges by using CSIBridge package. Continuous-span bridges (two to six) with straight haunched section are considered. All the dimensions used for generating bridge models are designed according to AASHTO LRFD Standards. Effect of various parameters such as span length, the depth ratios between haunched cross-section to mid-span cross-section (r), the length ratio between haunched section to span (α), span configuration and steel girder arrangement on natural frequencies are investigated by numerically generating one hundred fifty three bridge models. “r” and “α” values are set to be 0.5 - 2.0 and 0.1 - 0.5. The analysis results are given and discussed for the natural frequency of continuous-span composite steel bridges with straight haunched section.

Keywords

• Composite steel bridges,Natural frequency,Finite element analysis,Straight haunched,Non-prismatic cross-section

References

1. Wolek AL, Barton FW, Baber TT, Mckeel WT Jr. ‘Dynamic fields testing of the route 58 Meherrin river bridge’, Charlottesville (VA): Virginia Transportation Research Council; 1996.
2. Ontario Highway Bridge Design Code, 2nd. Edition .Ontario Ministry of Transportation and Communications, Downsview, Ontario, Canada, 1983.
3. 92 Austroads bridge design code, Section two-code design loads and its commentary. Austroads, Haymarket, Australia.
4. AASHTO. Standard specifications for highway bridges, 17th. Ed. Washington, DC: American Association of State Highway and Transportation Official, 2002.
5. AASHTO. LRFD bridge design specifications, 7th. Ed. Washington, DC: American Association of State Highway and Transportation Official, 2014.
6. Roeder CW, Barth KB, Bergman A. ‘ Improved live-load deflection criteria for steel bridges. Final report NCHRP’ Seattle (WA): University of Washington, 2002.
7. El-Mezaini N.,Balkaya Can, Citipitioglu E. (1991). ‘Analysis of frames with nonprismatic members.’, ASCE, Journal of Structural Engineering, 117(6), 1573-1592.
8. Balkaya Can (2001) 'Behavior and modeling of nonprismatic members having T-sections' ASCE, Journal of Structural Engineering, 127(8), 940-946.

9. Gao Qingfei, Wang Zonglin and Guo Binqiang, ‘ Modified formula of estimating fundamental frequency of girder bridge with variable cross-section’, Key Engineering MaterialsVol 540 pp 99-106, 2013.
10. CSIBridge 2017, Integrated 3D Bridge Analysis Software, Computer and Structures Inc., Berkeley, California.
11. Barth KE and H. Wu., ‘Development of improved natural frequency equations for continuous span steel I-girder bridges.’, Engineering Structures 29 (12): 3432-3442, 2007.
12. Warren J. Ashley, Sotelino Elisa D. And Cousins Thomas E. ‘ Finite element model efficiency for modal analysis of slab-on-girder bridges’, 2009.