Beirut explosion: TNT equivalence from the fireball evolution in the first 170 milliseconds

The evolution of the fireball resulting from the August 2020 Beirut explosion is traced using amateur videos taken during the first 400 ms after the detonation. Thirty-nine frames separated by 16.66–33.33 ms are extracted from six different videos located precisely on the map. Time evolution of the shock wave radius is traced by the fireball at consecutive time moments until about t≈170t≈170 ms and a distance d≈128d≈128 m. Pixel scales for the videos are calibrated by de-projecting the existing grain silos building, for which accurate as-built drawings are available, using the length, the width, and the height and by defining the line-of-sight incident angles. In the distance range d≈d≈ 60–128 m from the explosion center, the evolution of the fireball follows the Sedov–Taylor model with spherical geometry and an almost instantaneous energy release. This model is used to derive the energy available to drive the shock front at early times. Additionally, a drag model is fitted to the fireball evolution until its stopping at a time t≈500t≈500 ms at a distance d≈145±5d≈145±5 m. Using the derived TNT equivalent yield, the scaled stopping distance reached by the fireball and the shock wave-fireball detachment epoch within which the fireball is used to measure the shock wave are in excellent agreement with other experimental data. A total TNT equivalence of 200±80t200±80t at a distance d≈130d≈130 m is found. Finally, the dimensions of the crater size taken from a hydrographic survey conducted 6 days after the explosion are scaled with the known correlation equations yielding a close range of results. A recent published article by Dewey (Shock Waves 31:95–99, 2021) shows that the Beirut explosion TNT equivalence is an increasing function of distance. The results of the current paper are quantitatively in excellent agreement with this finding. These results present an argument that the actual mass of ammonium nitrate that contributed to the detonation is much less than the quantity that was officially claimed available

An Updated Review on the Effect of CFRP on Flexural Performance of Reinforced Concrete Beams

Abstract This detailed review looks at how carbon fiber-reinforced polymer (CFRP) may be used to improve the flexural capacity of reinforced concrete (RC) beams. It investigates the history, characteristics, and research trends of FRP composites, assesses various flexural strengthening methods utilizing FRP, and addresses the predictive power of finite-element (FE) modeling. The assessment highlights the importance of enhanced design codes, failure mode mitigation, and improved predictive modeling methodologies. It emphasizes the advantages of improving FRP reinforcement levels to meet code expectations and covers issues, such as FRP laminate delamination and debonding. The findings highlight the need of balancing load capacity and structural ductility, as well as the importance of material behavior and failure processes in accurate prediction. Overall, this review offers valuable insights for future research and engineering practice to optimize flexural strengthening with CFRP in RC beams

Silos structural response to blast loading

Extensive research work has been conducted to study the structural behavior of silos for various static load types; namely the grain load compression phases inside the silos and the thermal loads. However, very few investigations were related to the effect of different dynamic loads on silos, especially shock and blast loads. The aim of this research is to evaluate the structural response of grain silos due to massive blast loads. The Beirut explosion that occurred on August 04, 2020 is considered as a case study in a structural engineering approach with numerical non-linear finite element modeling of the silos. Due to the uncertainty of the exploded material mass, the magnitude of the explosion is defined as the numerical model magnitude that generates the same silos damages and sways recorded on site. The numerical study models are based on silos data (geometrical and material properties), and the use of the Conventional Weapons Effects Blast Loading (CONWEP), and the Coupled Eulerian-Lagrangian (CEL) methods to generate the blast loads. In addition, damage for the standing silos has been assessed, and final recommendations were stated. The results of this study define the magnitude of the explosion and the structural state of the remaining silos

Structural Assessment of Reinforced Concrete Beams Incorporating Waste Plastic Straws

The behavior of reinforced concrete beams containing fibers made of waste plastic straws (WPSs) under the three point bending test is examined. The effect of WPS fiber addition on the compressive and split tensile strength is reported. Four concrete mixes were prepared. The control mix PS-0 had a proportion of 1 cement: 1 sand: 2 coarse aggregate and a water cement ratio of 0.4. In the other three mixes PS-0.5, PS-1.5 and PS-3, 0%, 0.5%, 1.5% and 3% of WPS fiber (by volume) was added respectively. The results show that at 0.5% WPS, there is slight increase in compressive strength. However, beyond 0.5% addition, a decrease in compressive strength is observed. The split tensile strength shows a systematic increase with the addition of WPS fibers. The reinforced concrete beams containing WPS fibers show higher ductility as demonstrated by the larger ultimate tensile strain and ductility index (Δu/Δy). There is a tendency to have more fine cracks with the presence of WPS fibers