Prediction of Blast Loading and Its Impact on Buildings

Abstract

A bomb explosion within or near a building can cause catastrophic damage to both the external and internal structural frames, including the collapse of walls, shattering of windows, and failure of critical life-safety systems. The resulting loss of life and injuries may arise from various causes such as direct blast effects, structural collapse, debris impact, fire, and smoke. Furthermore, these events often hinder evacuation efforts, leading to additional casualties. Catastrophes caused by gas-chemical explosions generate dynamic loads significantly exceeding the original design capacities of structures. Consequently, extensive research over the past three decades has focused on the development of structural analysis and design techniques to resist such blast loads. Notably, studies on reinforced concrete (RC) elements have improved our understanding of how structural detailing influences behavior under blast conditions. This study investigates the response of RC columns subjected to constant axial and lateral blast loads using the finite element software ANSYS. Various boundary conditions were considered, employing meshless methods to reduce mesh distortion. The analysis involved applying a constant axial force to achieve equilibrium, followed by a short-duration lateral blast load to observe dynamic response over time. A comprehensive understanding of blast phenomena and structural dynamics is essential for the effective design of structures resistant to explosions.

Introduction

Over the past decades, considerable research has focused on understanding and mitigating the effects of earthquake and blast loads on structures. Earthquake engineering has evolved significantly, with advancements in seismic hazard analysis, material science, and retrofitting techniques. Similarly, blast engineering has gained attention due to threats from terrorism, industrial accidents, and warfare. Both fields now heavily rely on advanced computational tools, data from past events, and collaborative research to improve structural resilience.

Literature Review

1. Khadid et al. analyzed stiffened plates under blast loads using FEM and found stiffener configuration, mesh density, and strain rate sensitivity crucial for accurate modeling.

2. Pandey et al. evaluated blast effects on nuclear containment RC shells using nonlinear finite element models (DYNAIB), highlighting failure mechanisms and the need for dynamic analysis.

3. Remennikov et al. compared analytical and numerical methods (Lagrangian, Eulerian, ALE, FEM) for predicting building response to bomb blasts.

4. Dewey et al. studied blast wave behavior using particle trajectory analysis and applied conservation laws to model pressure and temperature changes.

5. Marchand et al. reviewed AISC blast-resistant design principles, emphasizing ductility, progressive collapse resistance, and lessons from real blast incidents.

6. Shope et al. investigated steel columns under axial and lateral blast loads using ABAQUS, finding slenderness, axial force, and boundary conditions greatly influence blast resistance.

7. Børvik et al. employed meshless and CEL methods in LS-DYNA to study steel containers under blast, offering high accuracy in fluid-structure interaction modeling.

8. Ngo et al. provided a foundational overview of blast loading physics, structural response, and design strategies, highlighting numerical methods like CFD and FEA.

9. Unde et al. and Mali et al. simulated RC structures under various blast conditions, advocating for modern design approaches to mitigate blast damage.

Proposed Methodology

ANSYS software is used for modeling RC structures under blast loads. It utilizes:

• SOLID65 element for nonlinear concrete behavior (cracking and crushing)

• LINK8 element for steel reinforcement (tension and compression)

This combination allows for realistic simulation of reinforced concrete behavior under dynamic loads.

Results and Discussion

A ground floor RC column was analyzed under blast loading. Variables included:

• Concrete strength: 40 MPa (NSC) vs. 80 MPa (HSC)

• Stirrup spacing: 400 mm (ordinary) vs. 100 mm (seismic)

Key findings:

• Higher-strength concrete allowed for reduced column size with equivalent axial capacity.

• Detailed ANSYS modeling with blast loading (from Oklahoma City bombing data) showed time-dependent deformation.

• The dynamic blast response was modeled using a triangular pressure profile lasting 1.3 ms.

Blast Parameter Calculation

A procedure is provided to compute free-field blast wave parameters (e.g., peak pressure, impulse, shock front velocity) using scaled distance and explosive weight, demonstrated with a 1814 kg surface burst at 5 meters stand-off.

Conclusion

Based on the findings presented and supported by existing literature, the overarching goal of this study is to develop a comprehensive procedure for calculating blast loads on structural systems, including both solid-wall and framed structures, whether or not they feature openings. Additionally, the study seeks to deepen the understanding of the dynamic behavior of reinforcing steel and concrete when subjected to the high strain rates typically induced by blast events. Through the detailed analysis carried out in this phase, valuable insights were gained into the response mechanisms of reinforced concrete columns exposed to blast loads. Finite element modeling revealed that for axially loaded columns, a specific threshold of lateral blast impulse exists—exceeding this critical value leads to structural collapse before reaching the permissible beam deflection limit. Moreover, the response of columns subjected to non-uniform blast loads is significantly affected by higher-order vibration modes, particularly under asymmetrical blast conditions. When comparing normal strength concrete (NSC) columns to high strength concrete (HSC) columns, it was observed that the critical impulse required to cause failure in HSC columns is substantially higher, a result attributed to their increased stiffness and strength. Another important conclusion is that while it is difficult to shield surfaces directly facing a blast, structural resilience can still be enhanced by increasing the stand-off distance between the structure and the blast source. Finally, for high-risk buildings such as tall public or commercial structures, the incorporation of design measures against extreme events—including blasts and high-velocity impacts—is essential. This study strongly recommends that existing building regulations and design standards be revised to include specific guidelines for abnormal loading scenarios and progressive collapse mitigation strategies. Enhancing ductility requirements within structural design codes is also advocated, as this would improve building performance under severe dynamic loads and contribute to overall structural safety and robustness.

References

[1] A.Ghani Razaqpur, Ahmed Tolba and Ettore Constestabile “Blast loading response of reinforced concrete panels reinforced with externally bonded GFRP laminates”. Science direct, Composites: Part B 38 (2007) 535-546. [2] A. Khadid et al. (2007), “Blast loaded stiffened plates” Journal of Engineering and Applied Sciences,Vol. 2. [3] ANSYS Theory manual, version 5.6, 2000. [4] Andrew Sorensen, Ph.D; and William L. McGill, Ph.D, P.E., M. ASCE, (2012) “Utilization of Existing Blast Analysis Software Packages for the Back-Calculation of Blast Loads”. [5] Alexander M. Remennikov, (2003) “A review of methods for predicting bomb blast effects on buildings”, Journal of battlefield technology, vol 6, no 3. pp 155-161. [6] A.K. Pandey et al. (2006) “Non-linear response of reinforced concrete containment structure under blast loading” Nuclear Engineering and design 236. pp.993-1002. [7] B. M. Lucconi, R.D. Ambrosini, R.F. Danesi “Analysis of building collapse under blast loads” Engineering Structures 26(2004) 63-71. [8] Biggs, J.M. (1964), “Introduction to Structural Dynamics”, McGraw-Hill, New York. [9] Demeter G. Fertis (1973), “Dynamics and Vibration of Structures”, A Wiley-Interscience publication pp. 343-434. [10] IS 456:2000 Indian Standard Plain and Reinforced Concrete Code of Practice. [11] J. M. Dewey (1971), “The properties of blast waves obtained from an analysis of the particle trajectories”. Proc. R. Soc. Lond. A.314,PP. 275-299. [12] Meena, A., Ramana, P.V., (2021) \"Assessment of structural wall stiffness impact due to blastload\", Materials Today: Proceedings. [13] Nitesh N. Moon (2009) master degree thesis on “Prediction of blast loading and its impact on buildings” from NITR. Priyawakode , D. H. Tupe , G. R. Gandhe, 2020, Blast Load Analysis on Bridge Subjected to Various Standoff Distance, International Journal Of Engineering Research & Technology (IJERT) Volume 09, Issue 07 (July 2020) [14] Rituparna Mazumdar, Dr. Nayanmoni Chetia, 0, A Review Paper on Blast Resistant Structure, International Journal of Engineering Research & Technology (IJERT) Volume 07, Issue 10 (October – 2018) [15] Sarita Singla, Pankaj Singla and Anmol Singla, “Computation of Blast Loading for a Multi-Storeyed Framed Building” International Journal of Research in Engineering and Technology,2015, e-ISSN: 2319 – 1163, p-ISSN: 2321 – 7308. [16] S. Unnikrishna Pillai and Devdas Menon (2003), “Reinforced Concrete Design”, Tata McGraw-Hill. [17] T. Ngo, P. Mendis, A. Gupta & J. Ramsay “Blast Loading and Blast Effects on Structures – An Overview” EJSE Special Issue: Loading on Structures (2007). [18] T. Borvik et al. (2009) “Response of structures to planar blast loads – A finite element engineering approach” Computers and Structures 87, pp 507–520, [19] T. Ngo, P. Mendis, A. Gupta & J. Ramsay, “Blast Loading and Blast Effects on structure”, The University of Melbourne, Australia, 2007. [20] Wai-Fah Chen and Atef F. Saleeb (1994), “Constitutive Equations for Engineering Materials- Volume 1: Elasticity and Modeling”, Elsevier Science B.V. [21] Yankelevsky, D., Schwarz, S., Brosh, B., (2013) “Full-scale field blast tests on reinforced concrete residential buildings-from Advances in Civil Engineering theory to practice,” International Journal of Protective Structures, vol. 4, no. 4, pp. 565–590.

Copyright

Copyright © 2025 Leena Kashiwar, Er. Bajrang Ambhore, Prof. Gaurav Hingwe. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.