Experimental Study on Falling Debris Impact: A Basis for Pancake-Type Progressive Collapse Assessment

Abstract:

Recent research on the progressive collapse of buildings has mainly focused on load redistribution following member failure, commonly referred to as “re-distributional progressive collapse”. However, “impact-type progressive collapse” remains less explored. This mechanism, often triggered by dynamic events such as falling debris or fire scenarios, introduces complex interactions that are difficult to capture using traditional quasi-static models, leaving a significant gap in our understanding of how impact-type progressive collapses occur. This study aims to bridge that gap by investigating the impact forces generated between concrete bodies of various geometries through an experimental campaign. Spherical, semi-spherical, and cubic concrete samples were dropped onto a fiber-reinforced concrete plate from controlled heights. A high-speed camera captured the impact for detailed analysis, while parameters such as impactor mass and velocity, contact radius, and concrete compressive strength were systematically varied. Using advanced data processing techniques, namely Variational Mode Decomposition (VMD), results showed that a 73% increase in impact velocity led to a 75% rise in maximum contact force. Geometry had a significant influence, with spherical and semi-spherical specimens generating up to 64% higher forces than cubes of equal mass. In contrast, compressive strength had a minor effect, raising contact force by only 9% despite a 50% strength increase. High-speed camera footage confirmed more concentrated impacts for spherical shapes, while no notable differences were found between spherical and semi-spherical specimens of equal weight but different contact radii.

• Periodical: Advances in Science and Technology (Volume 171)
• Pages: 59-66
• DOI: https://doi.org/10.4028/p-PQ3B5g
• Online since: December 2025
• Authors: Elahe Zeinali*, Foad Kiakojouri, Valerio De Biagi
• Keywords: Contact Force, Experimental Testing, Falling Debris, Impact, Progressive Collapse

References

[1] General Services Administration, Disproportionate Collapse Analysis and Design Guidelines for New Federal Office Buildings and Major Modernization Projects, Technical Report, General Services Administration, Washington, DC, 2003.

[2] Department of Defense, UFC 4-023-03: Design of Buildings to Resist Disproportionate Collapse, Technical Report, United Facilities Criteria, Washington, DC, 2013.

[3] Jawdhari, A., Orton, S., Izzuddin, B., & Cormie, D. (2018, April). Dynamic debris loading in flat plate and steel framed buildings. In Structures Conference 2018 (pp.299-310). Reston, VA: American Society of Civil Engineers.

DOI: 10.1061/9780784481349.029

[4] Kiakojouri, F., De Biagi, V., Chiaia, B., & Sheidaii, M. R. (2020). Progressive collapse of framed building structures: Current knowledge and future prospects. Engineering Structures, 206, 110061.

DOI: 10.1016/j.engstruct.2019.110061

[5] Kiakojouri, F., & De Biagi, V. (2024). Catenary mechanism in steel columns under extreme lateral loading: A basis for building progressive collapse analysis. Developments in the Built Environment, 20, 100556.

DOI: 10.1016/j.dibe.2024.100556

[6] Kiakojouri, F., Zeinali, E., Adam, J. M., & De Biagi, V. (2023). Experimental studies on the progressive collapse of building structures: A review and discussion on dynamic column removal techniques. Structures, 57, 105059.

DOI: 10.1016/j.istruc.2023.105059

[7] Kiakojouri, F., De Biagi, V., Marchelli, M., & Chiaia, B. (2024). A conceptual note on the definition of initial failure in progressive collapse scenarios. Structures, 60, 105921.

DOI: 10.1016/j.istruc.2024.105921

[8] Li, H., Chen, W., & Hao, H. (2019). Influence of drop weight geometry and interlayer on impact behavior of RC beams. International Journal of Impact Engineering, 131, 222-237.

DOI: 10.1016/j.ijimpeng.2019.04.028

[9] Sielicki, P. W., Ślosarczyk, A., & Szulc, D. (2019). Concrete slab fragmentation after bullet impact: An experimental study. International journal of protective structures, 10(3), 380-389.

DOI: 10.1177/2041419619854764

[10] Ning, J., Meng, F., Ma, T., & Xu, X. (2020). Failure analysis of reinforced concrete slab under impact loading using a novel numerical method. International Journal of Impact Engineering, 144, 103647.

DOI: 10.1016/j.ijimpeng.2020.103647

[11] Zhang, C., Gholipour, G., & Mousavi, A. A. (2021). State-of-the-art review on responses of RC structures subjected to lateral impact loads. Archives of Computational Methods in Engineering, 28(4), 2477-2507.

DOI: 10.1007/s11831-020-09467-5

[12] Adam, J. M., Buitrago, M., Bertolesi, E., Sagaseta, J., & Moragues, J. J. (2020). Dynamic performance of a real-scale reinforced concrete building test under a corner-column failure scenario. Engineering Structures, 210, 110414.

DOI: 10.1016/j.engstruct.2020.110414

[13] Zineddin, M., & Krauthammer, T. (2007). Dynamic response and behavior of reinforced concrete slabs under impact loading. International Journal of Impact Engineering, 34(9), 1517-1534.

DOI: 10.1016/j.ijimpeng.2006.10.012

[14] Senthil, K., Kubba, Z., Sharma, R., & Thakur, A. (2021, March). Experimental and numerical investigation on reinforced concrete slab under low velocity impact loading. IOP conference series: materials science and engineering, Vol. 1090, No. 1, p.012090. IOP Publishing.

DOI: 10.1088/1757-899x/1090/1/012090

[15] Zhan, T., Wang, Z., & Ning, J. (2015). Failure behaviors of reinforced concrete beams subjected to high impact loading. Engineering Failure Analysis, 56, 233-243.

DOI: 10.1016/j.engfailanal.2015.02.006

[16] De Biagi, V., & Marchelli, M. (2025). An experimental setup to study the collision force between brittle impacting bodies. International Journal of Impact Engineering, 196, 105160.

DOI: 10.1016/j.ijimpeng.2024.105160

[17] Zeinali, E., Kiakojouri, F., & De Biagi, V. (2025). Response of reinforced concrete beams subjected to debris impact: A simplified model. Engineering Failure Analysis, 178, 109661.

DOI: 10.1016/j.engfailanal.2025.109661

[18] PCB Piezotronics, "Model 203B ICP® Quartz Force Ring," [Online]. Available: https://www.pcb.com/products?m=203b.

[19] Photron. "FASTCAM Nova S12 High-Speed Camera." https://photron.com/fastcam-nova-s/.

[20] Zeiss. "Milvus 1.4/85." https://www.zeiss.com/consumer-products/us/photography/milvus/ milvus-1485.html.

[21] Hibbeler, R. C. (2004). Engineering mechanics: dynamics. Pearson Educación.