Dynamic Response of RC Structures Subjected to Blast Wave Shock Loading

Volume 12: Vibration, Acoustics and Wave Propagation ◽

10.1115/imece2012-88658 ◽

2012 ◽

Author(s):

Oruba Rabie ◽

Yahia M. Al-Smadi

Keyword(s):

Blast Wave ◽

Blast Waves ◽

Charge Weight ◽

Structural Components ◽

Reinforced Concrete Column ◽

Safety Criterion ◽

Rc Structures ◽

The Past ◽

Blast Wave Propagation ◽

The Stability

The collapse of significant structures caused by terrorist attacks in the past decades has motivated engineers to study the stability of current structural systems and their susceptibility to collapse. This collapse usually occurs due to blast waves generated by the high explosive bursts in the air that hit the structural components of the buildings leading to catastrophic damages which unfortunately happen before the evacuation. In an effort to find a safety criterion for buildings subjected to blasting; this study uses the nonlinear FEA explicit software LS-DYNA to highlight the effect of blast wave propagation on reinforced concrete column taking into account the standoff distance and charge weight variations. The effects of these two variables have been quantified through the comparison of resulted pressures, displacement and impulses.

Download Full-text

In silico investigation of biomechanical response of a human subjected to primary blast

10.1101/2021.09.16.460591 ◽

2021 ◽

Author(s):

Sunil Sutar ◽

Shailesh Ganpule

Keyword(s):

White Matter ◽

Blast Wave ◽

Rotational Motion ◽

Blast Waves ◽

Primary Blast ◽

Body Model ◽

The Past ◽

Biomechanical Response ◽

The Brain ◽

Full Body

The response of the brain to the explosion induced primary blast waves is actively sought. Over the past decade, reasonable progress has been made in the fundamental understanding of bTBI using head surrogates and animal models. Yet, the current understanding of how blast waves interact with the human is in nascent stages, primarily due to lack of data in humans. The biomechanical response in human is critically required so that connection to the aforementioned bTBI models can be faithfully established. Here, using a detailed, full-body human model, we elucidate the biomechanical cascade of the brain under a primary blast. The input to the model is incident overpressure as achieved by specifying charge mass and standoff distance through ConWep. The full-body model allows to holistically probe short- (<5 ms) and long-term (200 ms) brain biomechanical responses. The full-body model has been extensively validated against impact loading in the past. In this work, we validate the head model against blast loading. We also incorporate structural anisotropy of the brain white matter. Blast wave human interaction is modeled using a conventional weapon modeling approach. We demonstrate that the blast wave transmission, linear and rotational motion of the head are dominant pathways for the biomechanical loading of the brain, and these loading paradigms generate distinct biomechanical fields within the brain. Blast transmission and linear motion of the head govern the volumetric response, whereas the rotational motion of the head governs the deviatoric response. We also observe that blast induced head rotation alone produces a diffuse injury pattern in white matter fiber tracts. Lastly, we find that the biomechanical response under blast is comparable to the impact event. These insights will augment laboratory and clinical investigations of bTBI and help devise better blast mitigation strategies.

Download Full-text

Analysis of Blast Wave Parameters Depending on Air Mesh Size

Shock and Vibration ◽

10.1155/2018/3157457 ◽

2018 ◽

Vol 2018 ◽

pp. 1-18 ◽

Cited By ~ 6

Author(s):

Hrvoje Draganić ◽

Damir Varevac

Keyword(s):

Numerical Simulations ◽

Blast Wave ◽

Large Scale ◽

Wave Interaction ◽

Mesh Size ◽

Blast Waves ◽

3D Environment ◽

Close Range ◽

Blast Wave Propagation ◽

Optimal Mesh

Results of numerical simulations of explosion events greatly depend on the mesh size. Since these simulations demand large amounts of processing time, it is necessary to identify an optimal mesh size that will speed up the calculation and give adequate results. To obtain optimal mesh sizes for further large-scale numerical simulations of blast wave interactions with overpasses, mesh size convergence tests were conducted for incident and reflected blast waves for close range bursts (up to 5 m). Ansys Autodyn hydrocode software was used for blast modelling in axisymmetric environment for incident pressures and in a 3D environment for reflected pressures. In the axisymmetric environment only the blast wave propagation through the air was considered, and in 3D environment blast wave interaction and reflection of a rigid surface were considered. Analysis showed that numerical results greatly depend on the mesh size and Richardson extrapolation was used for extrapolating optimal mesh size for considered blast scenarios.

Download Full-text

Numerical Analysis of the Blast Wave Propagation due to Various Explosive Charges

Advances in Civil Engineering ◽

10.1155/2020/8871412 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Lucia Figuli ◽

Damjan Cekerevac ◽

Chiara Bedon ◽

Bohuš Leitner

Keyword(s):

Wave Propagation ◽

Numerical Analysis ◽

Blast Wave ◽

Control Point ◽

Blast Waves ◽

Size Type ◽

Explosive Charges ◽

Blast Wave Propagation ◽

Comparative Results ◽

Basic Features

Blast events and scenarios, as known, represent extreme phenomena that may result in catastrophic consequences, both for humans and structures. Accordingly, for engineering applications, the reliable description of expected blast waves is a crucial step of the overall design process. Compared to ideal theoretical formulations, however, real explosive events can be strongly sensitive to a multitude of parameters and first of all to the basic features (size, type, shape, etc.) of the charge. In this regard, several advanced computer codes can be used in support of design and research developments. Besides, the input parameters and solving assumptions of refined numerical methods are often available and calibrated in the literature for specific configurations only. In this paper, with the support of the ANSYS Autodyn program, special care is dedicated to the numerical analysis of the blast wave propagation in the air due to several charges. Five different explosives are taken into account in this study, including RDX, DAP-2, DAP-E, Polonit-V, and homemade ANFO. The effects of different mixtures are thus emphasized in terms of the predicted blast wave, as a function of a given control point, direction, explosive mass, and composition. As shown, relatively scattered peak pressure estimates are collected for a given explosive. Comparative results are hence proposed towards selected experimental data of the literature, as well as based on simple analytical predictions. The collected overpressure peak values are thus discussed for the selected explosive charges.

Download Full-text

Numerical Simulation of Blast-Wave Propagation in a Small Two-Medium Duct

Journal of Mechanics ◽

10.1017/s172771910000277x ◽

2009 ◽

Vol 25 (3) ◽

pp. 313-322 ◽

Cited By ~ 2

Author(s):

S.-M. Liang ◽

J.-C. Yuan

Keyword(s):

Wave Propagation ◽

High Resolution ◽

Blast Wave ◽

Equations Of State ◽

Blast Waves ◽

Weno Scheme ◽

Navier Stokes ◽

Viscous Effects ◽

Resolution Scheme ◽

Blast Wave Propagation

AbstractIn this study, a small two-medium duct with blast-wave propagation is numerically investigated by a high-resolution Euler/Navier-Stokes solver. The solver has a feature of treatment of the Tait equations of state for two media. One of the two media is water which is envisaged as a blood. The second medium is another liquid, used to simulate body's clot or tissue. The duct wall has a mass diffusion effect in addition to viscous effects. Since two different media are considered, the reflection and transmission of an underwater blast wave passing through the interfaces of the two media with different sound impedances are inevitable. The different properties of liquids may cause numerical oscillation at interfaces for very weak blast waves for a high-resolution scheme such as a 5th-order WENO scheme. In order to overcome this difficulty of numerical fictitious oscillation, a third-order WENO scheme was used. It was found that computed pressures of the transmitted blast wave for four kinds of simulated tissues are in good agreements with those obtained by the acoustic principle. Moreover, for the case of a simulated clot, the pressure force and impulse acted on the clot surface are investigated for different intensities of blast waves.

Download Full-text

Enhancement of blast wave parameters due to shock focusing from multiple simultaneously detonated charges

International Journal of Protective Structures ◽

10.1177/20414196211033310 ◽

2021 ◽

pp. 204141962110333

Author(s):

Amir Zaghloul ◽

Alex Remennikov ◽

Brian Uy

Keyword(s):

Blast Wave ◽

Blast Waves ◽

Terrorist Attacks ◽

Blast Loads ◽

Single Charge ◽

Shock Focusing ◽

Approximate Methods ◽

The Past ◽

Wave Parameters ◽

Blast Parameters

With the increase of terrorist attacks over the past decades, many engineering societies have started issuing design guides to calculate blast loads on structures. While such guides can be successfully used to assess blast loads due to single detonations, the effects of multiple detonations are often overlooked. In this research, the enhancement in blast parameters resulting from simultaneously detonating multiple charges is investigated, emphasising the interaction of blast waves with narrow targets. A parametric CFD study using the finite volume code Viper::Blast was performed where the number of charges, their arrangement, and the scaled stand-off distances were changed. It is found that, when detonated simultaneously, multiple charges return much higher pressure and impulse values compared to an equivalent single charge. Moreover, an arced arrangement of multiple charges is more efficient than a flat arrangement in enhancing blast wave parameters. Such enhancement is beneficial in scenarios involving demolition. Approximate methods to compute blast wave parameters from multiple simultaneously detonated spherical charges are presented in this study, where pressure and impulse from multiple charges can be computed by only knowing the parameters resulting from an equivalent single charge.

Download Full-text

Stability and Folding of the Unusually Stable Hemoglobin from Synechocystis is Subtly Optimized and Dependent on the Key Heme Pocket Residues.

Protein and Peptide Letters ◽

10.2174/0929866527666200613220245 ◽

2020 ◽

Vol 27 ◽

Author(s):

Sheetal Uppal ◽

Mohd. Asim Khan ◽

Suman Kundu

Keyword(s):

Molten Globule ◽

Life Forms ◽

Model System ◽

Heme Pocket ◽

The Past ◽

Specific Manner ◽

Delivery Vehicles ◽

The Stability ◽

Key Residues ◽

Synechocystis Sp

Aims: The aim of our study is to understand the biophysical traits that govern the stability and folding of Synechocystis hemoglobin, a unique cyanobacterial globin that displays unusual traits not observed in any of the other globins discovered so far. Background: For the past few decades, classical hemoglobins such as vertebrate hemoglobin and myoglobin have been extensively studied to unravel the stability and folding mechanisms of hemoglobins. However, the expanding wealth of hemoglobins identified in all life forms with novel properties, like heme coordination chemistry and globin fold, have added complexity and challenges to the understanding of hemoglobin stability, which has not been adequately addressed. Here, we explored the unique truncated and hexacoordinate hemoglobin from the freshwater cyanobacterium Synechocystis sp. PCC 6803 known as “Synechocystis hemoglobin (SynHb)”. The “three histidines” linkages to heme are novel to this cyanobacterial hemoglobin. Objective: Mutational studies were employed to decipher the residues within the heme pocket that dictate the stability and folding of SynHb. Methods: Site-directed mutants of SynHb were generated and analyzed using a repertoire of spectroscopic and calorimetric tools. Result: The results revealed that the heme was stably associated to the protein under all denaturing conditions with His117 playing the anchoring role. The studies also highlighted the possibility of existence of a “molten globule” like intermediate at acidic pH in this exceptionally thermostable globin. His117 and other key residues in the heme pocket play an indispensable role in imparting significant polypeptide stability. Conclusion: Synechocystis hemoglobin presents an important model system for investigations of protein folding and stability in general. The heme pocket residues influenced the folding and stability of SynHb in a very subtle and specific manner and may have been optimized to make this Hb the most stable known as of date. Other: The knowledge gained hereby about the influence of heme pocket amino acid side chains on stability and expression is currently being utilized to improve the stability of recombinant human Hbs for efficient use as oxygen delivery vehicles.

Download Full-text

Sphingolipids of Asteroidea and Holothuroidea: Structures and Biological Activities

Marine Drugs ◽

10.3390/md19060330 ◽

2021 ◽

Vol 19 (6) ◽

pp. 330

Author(s):

Timofey V. Malyarenko ◽

Alla A. Kicha ◽

Valentin A. Stonik ◽

Natalia V. Ivanchina

Keyword(s):

Marine Invertebrates ◽

Biological Activities ◽

Complete Information ◽

Structural Features ◽

Marine Organisms ◽

Structural Components ◽

Chemical Structures ◽

The Past ◽

Complex Lipids ◽

Complex Sphingolipids

Sphingolipids are complex lipids widespread in nature as structural components of biomembranes. Commonly, the sphingolipids of marine organisms differ from those of terrestrial animals and plants. The gangliosides are the most complex sphingolipids characteristic of vertebrates that have been found in only the Echinodermata (echinoderms) phylum of invertebrates. Sphingolipids of the representatives of the Asteroidea and Holothuroidea classes are the most studied among all echinoderms. In this review, we have summarized the data on sphingolipids of these two classes of marine invertebrates over the past two decades. Recently established structures, properties, and peculiarities of biogenesis of ceramides, cerebrosides, and gangliosides from starfishes and holothurians are discussed. The purpose of this review is to provide the most complete information on the chemical structures, structural features, and biological activities of sphingolipids of the Asteroidea and Holothuroidea classes.

Download Full-text

Copper Phyllosilicates-Derived Catalysts in the Production of Alcohols from Hydrogenation of Carboxylates, Carboxylic Acids, Carbonates, Formyls, and CO2: A Review

Catalysts ◽

10.3390/catal11020255 ◽

2021 ◽

Vol 11 (2) ◽

pp. 255

Author(s):

Dien-Thien To ◽

Yu-Chuan Lin

Keyword(s):

Carboxylic Acids ◽

Catalytic Performance ◽

Spatial Effect ◽

Synthesis Methods ◽

The Past ◽

Surface Areas ◽

Preparation Conditions ◽

Remedial Actions ◽

The Stability ◽

Size Interaction

Copper phyllosilicates-derived catalysts (CuPS-cats) have been intensively explored in the past two decades due to their promising activity in carbonyls hydrogenation. However, CuPS-cats have not been completely reviewed. This paper focuses on the aspects concerning CuPS-cats from synthesis methods, effects of preparation conditions, and dopant to catalytic applications of CuPS-cats. The applications of CuPS-cats include the hydrogenation of carboxylates, carboxylic acids, carbonates, formyls, and CO2 to their respective alcohols. Besides, important factors such as the Cu dispersion, Cu+ and Cu0 surface areas, particles size, interaction between Cu and supports and dopants, morphologies, and spatial effect on catalytic performance of CuPS-cats are discussed. The deactivation and remedial actions to improve the stability of CuPS-cats are summarized. It ends up with the challenges and prospective by using this type of catalyst.

Download Full-text

Thermodynamic and Energy Efficiency Analysis of a Domestic Refrigerator Using Al2O3 Nano-Refrigerant

Sustainability ◽

10.3390/su13105659 ◽

2021 ◽

Vol 13 (10) ◽

pp. 5659

Author(s):

Farhood Sarrafzadeh Javadi ◽

Rahman Saidur

Keyword(s):

Temperature Gradient ◽

Technological Changes ◽

Nanoparticle Concentration ◽

Evaporator Temperature ◽

Domestic Refrigerator ◽

The Past ◽

Nano Lubricant ◽

The Stability ◽

Energy Efficiency Analysis ◽

Al2o3 Nanofluid

Refrigeration systems have experienced massive technological changes in the past 50 years. Nanotechnology can lead to a promising technological leap in the refrigeration industry. Nano-refrigerant still remains unknown because of the complexity of the phase change process of the mixture including refrigerant, lubricant, and nanoparticle. In this study, the stability of Al2O3 nanofluid and the performance of a nano-refrigerant-based domestic refrigerator have been experimentally investigated, with the focus on the thermodynamic and energy approaches. It was found that by increasing the nanoparticle concentration, the stability of nano-lubricant was decreased and evaporator temperature gradient was increased. The average of the temperature gradient increment in the evaporator was 20.2% in case of using 0.1%-Al2O3. The results showed that the energy consumption of the refrigerator reduced around 2.69% when 0.1%-Al2O3 nanoparticle was added to the system.

Download Full-text