Evaluation the progressive collapse of steel structures with beam to column - tree connections

Document Type : Original Article


1 Department of Civil Engineering, Persian Gulf University, Shahid Mahini Street, Bushehr, Iran,

2 Department of Civil Engineering, Persian Gulf University

3 department of civil engineering, persian gulf university

4 department of civil engineering, Persian Gulf university, bushehr


Progressive collapse begins by removing the local bearing capacity of a small part of the structures and causes structural failures which are not directly affected by the initial local event. In this research, the behavior of 3 and 6-story moment resisiting structures with tree column bending connections and span length to story height ratios (L/H) of 1.0, 1.5 and 2.0 were investigated under the effects of progressive collapse. In comparison between nonlinear static and dynamic analysis in terms of performance, the structure has almost the same response in two analysis. The deformations are slightly higher in nonlinear static analysis due to the fact that the dynamic load factor is more than actual in static nonlinear analysis. The maximum deformation occurs at the corner scenarios, which is higher if it is located in the middle story scenarios. Structures with more stories show better performance against progressive collapse, in other words, more structural elements in removed column connection area and upper stories means the structure has more alternate paths to carry and transfer the extra load. Therefore the number of critical members will decrease. Increasing the L/H ratio raises tensions and deformations in removed column connection zone. Three-story structures with L/H ratio of 1.0 are throughtly resistant to progressive collapse.and their resistance decreases by increasing L/H ratio. Six-story structures with L/H ratio of 2.0 are relatively resistant, because they have more structural members to carry extra load although their L/H ratio is relatively high.


  1. American Society of Civil Engineers (ASCE/SEI     41-13), “Seismic Evaluation,” 2013.##
  2. General Services Administration (GSA), “Progressive collapse analysis and design guideline for new federal office buildings and major modernization,” Washington (DC), 2003.##
  3. United States Department of Defence (DOD), “Design of building to resist progressive collaps,” Unified Facilities Criteria (UFC), 4-023-03, Washington (DC), 2013.##
  4. B. R. Ellingwood, R. Smilowitz, D. O. Dusenberry, D. Duthinh, H. S. Lew, and N. J. Carino, “Best practices for reducing the potential for progressive,” collapse in buildings, Gaithersburg: National Institute of Standards and Technology, ‏ 2007.##
  5. A. Eidi and S. Golizadefard, “Progressive collapse of steel structures and exploring the causes of the Plasco’s building collapse,” 4th national conference of civil engineering and architecture, K. N. Toosi University, 2017. (In Persian)##
  6. B. Badarlu, “Studing the progressive collapse of concrete special moment frames caused by column removing,” Passive defense, IH University, 2018. (In Persian)##
  7. T. Kim and J. Kim, “Collapse analysis of steel moment frames with various seismic connections,” Journal of Constructional Steel Research, vol. 65, no. 6, pp. 1316-1322, 2009.##
  8. J. L. Liu, “Preventing progressive collapse through strengthening beam-to-column connection,” Part 2: Finite element analysis, Journal of Constructional Steel Research, vol. 66, no. 2, pp. 238-247, 2010.##
  9. B. Yang and K. H. Tan, “Robustness of bolted-angle connections against progressive collapse: Mechanical modelling of bolted-angle connections under tension,” Engineering Structures 57, pp. 153-168, 2013.##
  10. P. M. Stylianidis and D. A.  Nethercot, “Modelling of connection behaviour for progressive collapse analysis,” Journal of Constructional Steel Research, vol. 113, pp. 169-184, 2015.##
  11. R. Rahnavard, F. F. Z. Fard, A. Hosseini, and M.  Suleiman, “Nonlinear analysis on progressive collapse of tall steel composite buildings,” Case studies in construction materials, vol. 8, pp. 359-379, 2018.##
  12. L. L. Li, G. Q. Li, B. Jiang, and Y. Lu, “Analysis of robustness of steel frames against progressive collapse,” Journal of Constructional Steel Research, vol. 143, pp. 264-278, 2018.##
  13. Iran National Building Code, Part 6, Loading on Structures, Ministry of Road and Urban Development, 2013. (In Persian)##
  14. Iran National Building Code, Part 10, Design of Steel Structures, Ministry of Road and Urban Development, 2013. (In Persian)##
  15. Road, “Housing and Urban Development Research Center,” Iranian code of practice for seismic-resistant design of buildings, Iranian Building Code, Standard no. 2800, 4th Edn., 2014. (In Persian)##
  16. T. Kim, U. S. Kim, and J.  Kim, “Collapse resistance of unreinforced steel moment connections,” The Structural Design of Tall and Special Buildings, vol. 21, no. 10, pp. 724-735, 2012.##