Design of Steel Footbridges for Unpredictive Loadings by STAAD Pro: LRFD vs. ASD for Cost Saving

  • Armghan Naeem University of Engineering and Technology Taxila
  • Muhammad Muneeb University of Engineering and Technology Lahore
  • Asad Yousaf University of Engineering and Technology Taxila
  • Muhammad Mohtasham Naeem University of Engineering and Technology Kala Shah Kaku

Abstract

Steel footbridges are common means of connecting two zones separated by any kind of physical obstruction to the pedestrian crossing. In the last century, they were mostly designed using manual calculations. With the advent of powerful software, the designing process has become more accurate and less time-consuming. In this paper, complete designing process of steel footbridges is conducted using STAAD Pro: a dedicated steel structure design and analysis software, under unpredictive loading, i.e., dead, live, pedestrian, wind and seismic loading. Two design approaches are popular in steel footbridges designing. These are allowable stress design (ASD) and load and resistance factor design (LRFD), and both are compared with the focus on material/cost saving as cost is the major issue in underdeveloped and overpopulated countries. The critical load combination giving a minimum factor of safety for both approaches is also obtained. It is evaluated that the LRFD design approach results in stronger and lighter structures for unpredictive loadings. The factor of safety for ASD is 20% lower than that of LRFD, and thus LRFD provides material/cost savings of about 20% compared to ASD.

Keywords

steel bridges, LRFD, ASD, STAAD Pro, loading combinations, cost reduction,

References

1. A. Vashisth, M. Kumar, A. Kumar, Ashish, Design of Foot Bridge, 2012, doi: 10.13140/RG.2.2.17428.81285.
2. L. Muir, C.J. Duncan, The AISC 2010 Specification and the 14th Edition Steel Construction Manual, [in:] Structures Congress 2011, April 14–16, 2011, Las Vegas, Nevada, United States, pp. 661–675, doi: 10.1061/41171(401)58.
3. B.R. Ellingwood, LRFD: implementing structural reliability in professional practice, Engineering Structures, 22(2): 106–115, 2000, doi: 10.1016/S0141-0296(98)00099-6.
4. C.W. Roeder, Comparison of LRFD and allowable stress design methods for steel structures, 5th Seminario de Ingenieria Estructural, San Jose, Costa Rica, November, 1990.
5. S.-H. Lin, W. Yu, T.V. Galambos, ASCE LRFD method for stainless steel structures, [in:] CCFSS Proceedings of International Speciality Conference on Cold-Formed Steel Structures (1971–2018), 1, University of Missouri–Rolla, 1990, https://scholarsmine.mst.edu/isccss/10iccfss/10iccfss-session5/1.
6. T. Culp, R. Mathur, LRFD vs. ASD, Modern Steel Construction, 31(11): 24–27, 1991.
7. R. Soegiarso, H. Adeli, Optimum load and resistance factor design of steel space-frame structures, Journal of Structural Engineering – ASCE, 123: 184–192, 1997, doi: 10.1061/(ASCE)0733-9445(1997)123:2(184).
8. M.S. Hayalioglu, S.O. Degertekin, Minimum cost design of steel frames with semi-rigid connections and column bases via genetic optimization, Computers & Structures, 83(21–22): 1849–1863, 2005 doi: 10.1016/j.compstruc.2005.02.009.
9. H. Warren, H.B. Manbeck, J.J. Janowick, R.W. Witmer, Differences in LRFD and ASD outcomes for hardwood glue-laminated bridges, Transactions of ASAE, 41(3): 803–811, 1998.
10. J.S. Groenier, Load rating of wood bridges using LRFD and ASD, [in:] Structures Congress 2006, May 18-21, 2006, St. Louis, Missouri, United States, doi: 10.1061/40889(201)139.
11. D.H. Choi, H. Yoo, J.L. Shin, Comparative study on stability evaluation methods with ASD and LRFD for steel cable-stayed bridges [in:] Proceedings of the 8th Pacific Structural Steel Conference – Steel Structures in Natural Hazards, PSSC 2007, Wairakei, New Zealand, pp. 165–170, 2007.
12. R. Shreedhar, S. Mamadapur, Analysis of T-beam bridge using finite element method, International Journal of Engineering and Innovative Technology (IJEIT), 2: 340–346, 2012.
13. K.P. Kumar, B. Shankar, P.M. Rao, Evaluation and design of flyover using Staad pro, International Journal of Professional Engineering Studies, 7(2): 31–36, 2016.
14. S. Indra, M. Efran, Mohammad, I.K. Dedi Wijaya, Alternative design of the building structure of steel frame bridge type steel arch with warren frame in Tukad Bangkung Bridge in Badung – Bali, Journal of Sustainable Technology and Applied Science, 1(1): 22–27, 2020, doi: 10.36040/jstas.v1i1.2610.
15. American Society of Civil Engineers, Minimum design loads and associated criteria for buildings and other structures, American Society of Civil Engineers, 2017, doi: 10.1061/9780784414248.
16. C.G. Salmon, J.E. Johnson, Steel Structures: Design and Behavior, 4th ed., Harper Collins, New York, NY, 1997.
17. W. Lin, T. Yoda, Bridge Planning and Design, Bridge Engineering: Classifications, Design Loading, and Analysis Methods, pp. 31–58, 2017, Butterworth-Heinemann.
18. T.V. Galambos, M.K. Ravindra, Load and resistance factor design, Engineering Journal, AISC, 18(3): 78-84, 1981.
19. K.P. Kumar, D.S. Prakash, Planning analysis and design of industrial building using STAAD PRO, International Journal of Pure and Applied Mathematics, 119(17d): 131–137, 2018.
20. S.M. Harle, Analysis by STAAD-PRO and design of structural elements by MATLAB, Journal of Asian Scientific Research, 7(5): 145–164, 2017, doi: 10.18488/journal.2.2017.75.145.164.
21. T. Zokaie, AASHTO-LRFD live load distribution specifications, Journal of Bridge Engineering, 5(2): 131–138, 2000.
22. Uniform Building Code (UBC-97), Structural Engineering Design Provisions, International Conference of Building Officials, Whittier, 1997, p. 492.
Published
Mar 30, 2022
How to Cite
NAEEM, Armghan et al. Design of Steel Footbridges for Unpredictive Loadings by STAAD Pro: LRFD vs. ASD for Cost Saving. Computer Assisted Methods in Engineering and Science, [S.l.], v. 28, n. 4, p. 351–367, mar. 2022. ISSN 2299-3649. Available at: <https://cames.ippt.pan.pl/index.php/cames/article/view/399>. Date accessed: 28 june 2022. doi: http://dx.doi.org/10.24423/cames.399.
Section
Articles