| 1. |
- Lozano Mendoza, Fabio José, 1991, et al.
(författare)
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Experimental validation of two CFD solvers for prediction of blast loading in an urban environment
- 2023
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Ingår i: 26th International Symposium on Military Aspects of Blast and Shock.
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Konferensbidrag (refereegranskat)abstract
- The evolution and propagation of a blast wave in urban environments differ substantially from those of free-field blast waves. The interaction of the blast wave with obstacles along its path gives rise to physical phenomena such as reflection, diffraction and superposition which significantly increase the complexity of the loading. Therefore, for such environments, simplified engineering tools commonly used for predicting shock wave parameters in free-field settings are not sufficient. Indeed, to properly estimate the characteristics of the blast loading for such cases, it may be necessary to use more advanced tools based on computational fluid dynamics (CFD). However, CFD codes must be validated against experimental data before they can be implemented in real life cases. In this study, the open-source CFD solver blastFoam [1] was validated against a scaled (1:5) experimental campaign of an explosion of PETN at a street intersection. The setup of the experiment consisted of four concrete boxes arranged in a 2×2 layout. Multiple locations of the charge were tested. In general, very good agreement between the experimental results and the blastFoam simulations was obtained. The study showed that blastFoam was able to describe the arrival and amplitude of both the main shock wave and secondary waves with a good level of accuracy at multiple points in the configuration.
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| 2. |
- Lozano Mendoza, Fabio José, 1991
(författare)
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Explosions in urban environments: Modelling of gas explosions and risk of premature shear failure in reinforced concrete structures
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The risk for accidental gas explosions in urban environments has increased in Sweden in recent years. This is due to densification of existing urban centres and the rise of vehicles powered by alternative fuels. Because of this, blast-resistant design of reinforced concrete (RC) structures may eventually become a common aspect of urban development and structural engineering. This thesis aims at expanding the knowledge concerning explosion and blast loads in urban environments and the response of RC structures subjected to it. Two key research areas were identified. The first one deals with the strength of vapour cloud explosions (VCEs) on urban roads. The strength of the blast source is a necessary input to predict the blast load generated by VCEs. However, there is much subjectivity and inconsistency today in the determination of the explosion strength, particularly for the conditions on urban roads. This work used computational fluid dynamics (CFD) calculations in combination with the principles of factorial design to determine the expected strength for several explosion scenarios on urban roads and identify the most significant parameters affecting the resulting strength. For the studied scenarios, the explosion strength varied approximately from 2 kPa to 100 kPa. Moreover, the number of vehicles in the transversal direction (i.e., vehicles standing side by side) was found to have the most significant effect on the explosion pressure. The other area is concerned with the uncertainties related to the failure modes of blast-loaded RC one-way slabs. The motivation behind this research area is the need to prevent brittle shear failure in blast-loaded RC elements. The Monte Carlo method was used to determine the probability of premature shear failure of the blast-loaded slabs considering the uncertainties associated with the materials, geometry, and resistance models. The slabs were initially designed to have a balanced failure (i.e., the resistance to shear and bending failure are theoretically equal). Bending failure was found to be the expected failure mode for the studied cases. However, the likelihood of shear failure (particularly for slabs without stirrups) may still be considered relatively high, depending on the risk tolerability of a given design. Thus, an additional partial factor to enhance the confidence level regarding the preferred failure mode was put forward.
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| 3. |
- Peterson, Viktor, et al.
(författare)
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The effect of explosions in road tunnels on critical structural elements
- 2023
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Ingår i: Expanding Underground - Knowledge and Passion to Make a Positive Impact on the World. - : CRC Press/Balkema. ; , s. 3263-3271
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Konferensbidrag (refereegranskat)abstract
- In the present paper, the walls of a concrete frame used for over-decking in a road tunnel were first designed using the relevant design provisions. The response of the wall was then analysed using non-linear finite element analysis, and the results of the finite element analysis were compared to what was predicted using the design guidelines. Additionally, simulations of the blast load resulting from gas leakage during transportation were conducted as a separate study. The results from two vapour clouds containing gases of hydrogen and propane were compared.
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