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1

Analysis of the structural response of Beirut port concrete silos under blast loading

Ismail Sahar Ali, Raphael Wassim, Durand Emmanuel, Kaddah Fouad, Geara Fadi

Archives of Civil Engineering

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2021

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Vol. 67, nr 3

619--638

EN

Several months after August 4, 2020, Lebanon is still recovering from the enormous explosion at the port of Beirut that killed more than 200 people and injured more than 7500. This explosion ripped the city to shreds and significantly damaged the Beirut port silos. Saint Joseph University of Beirut “the school of engineering ESIB” in collaboration with “Amann” Engineering performed a 3D scan of the Beirut port silos to assess the silos’ level of damage. The obtained data was then compared to the numerical modelling results, obtained from Abaqus explicit, in order to estimate the blast magnitude and to check if the pile foundation can be reused in building new silos at the same place due to the limited space available at the port of Beirut while considering the soil-foundation-structure interaction effect. In addition, the silos’ structural response against the filling of the silos at the time of explosion was investigated. The displacement of the silos and the amount of silos’ damage obtained from the fixed and flexible numerical models indicate that a blast magnitude of 0.44 kt TNT (approximately 1100 tons of Ammonium Nitrate) best estimates the 20 to 30 cm silos’ tilting in the direction of the blast. In addition, the soil and the foundation played a positive role by absorbing part while dissipating less amount of the blast energy. Also, the grains at the time of the event did not affect the silos’ deformation and damage amount. Noting that the displacement of the pile foundation exceeded all limits set by design codes, indicating that the pile foundation cannot be reused to build new silos at the same place.

2

Mitigation of blast load risk on reinforced concrete structures considering different design alternatives

Ibrahim Y. E., Almustafa M.

Archives of Civil Engineering

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2020

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Vol. 66, nr 3

225--238

EN

The purpose of this study is to investigate a structure’s response to blast loading when composite columns are used instead of conventional reinforced concrete (RC) cross sections and when a conventional structure is retrofitted with braces. The study includes conducting dynamic analyses on three different structures: a conventional reference RC structure, a modified structure utilizing composite columns, and a modified structure retrofitted with steel braces. The two modified structures were designed in order to investigate their performance when subjected to blast loading compared to the conventional design. During the dynamic analyses, the structures were exposed to simulated blast loads of multiple intensities using the finite-element modelling software, SeismoStruct. To evaluate their performance, the responses of the modified structures were analyzed and compared with the response of the conventional structure. It was concluded that both the structure with composite columns and the steel brace structure experienced less damage than the conventional model. The best performance was obtained through the steel brace structure.

3

Experimental and analytical investigation of point fixed corrugated metal sheets subjected to blast loading

Fischer Kai, Stolz Alexander, Roller Christoph

Engineering Transactions

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2019

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Vol. 67, iss. 1

133--142

EN

Besides the primary threats of a blast loading scenario, flying fragments from nonstructural elements could be a further threat to exposed humans. Point fixed corrugated metal sheets are often applied as facade elements. This paper focuses on the analysis of the dynamic bearing resistance and related pull-out behaviour of such elements. In a first step, the dynamic bearing capacity is investigated by an experimental study. Different sheet thicknesses and dimensions are examined for different loading levels using shock tube experiments. Based on the experimental results an engineering model is applied to predict the overall bearing capacity of the investigated corrugated metal sheet elements using mathematical optimisation methods. In a second step, the comparison to an analytical approach to quantify the prognostic capacity of the theoretical assessment method is addressed. Obtained results enable fast and effective quantification of expected damage effects and can be integrated into an overall risk and resilience analysis scheme.

4

Numerical study of selected military vehicle chassis subjected to blast loading in terms of tire strength improving

Baranowski P., Malachowski J.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2015

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Vol. 63, nr 4

867--878

EN

In the paper a chosen model of the light armoured vehicle was tested in terms of blast loading. More precisely, the blast propagation and interaction with the tire behaviour and suspension system elements of the light-armoured vehicle (LAV) was simulated. The chosen military vehicle meets the requirements of levels 2A and 2B of STANAG 4569 standard. Based on the obtained results, two modifications were proposed for the strength and resistance improvement of the wheel. The first consisted of inserting the rubber runflat ring inside the tire, whereas in the second the honeycomb-like composite wheel was implemented. Non-linear dynamic simulations were carried out using the explicit LS-Dyna code, with multi-material Arbitrary Lagrangian-Eulerian formulation for simulation the blast process.

5

Failure Assessment of Steel-Concrete Composite Column Under Blast Loading

Budziak M., Garbowski T.

Engineering Transactions

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2014

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Vol. 62, iss. 1

61--84

EN

Composite column as a key structural member can be subjected to a blast load as a result of an accident or a terrorist threat. In this paper, a method for assessing the blast resistance of a composite concrete-filled column is proposed. Moreover, different methods of enhancing composite member resistance to explosions are investigated. The blast situation is modeled in the FEM software using the CONWEP tool. This empirical formulation is relatively cheap from the computational point of view, as well as precise enough, hence it was chosen for this work purposes. Material models are based on well known elasto-plastic with linear hardening concepts. Important phenomenons are also taken into account, such as: contact formulation between the column components, strain rate dependence, damage initiation and evolution. Simulations are conducted for the most common type of explosion – surface blast. Its main feature is the effect of reflection of the ground surface and hence, amplification of the blast wave after the charge ignition. Results are presented in terms of minimum TNT mass equivalent required for a column member failure.

6

An Investigation of TNT Equivalence of Hemispherical PE4 Charges

Rigby S., Sielicki P.

Engineering Transactions

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2014

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Vol. 62, iss. 4

423–-435

EN

The TNT equivalence of an explosive is given as the equivalent mass of TNT required to produce a blast wave of equal magnitude to that produced by a unit weight of the explosive in question. Currently, there is a lack of agreement in the literature on the TNT equivalence (TNTeq) of PE4. This paper presents a combined numerical and experimental investigation of TNTeq for hemispherical PE4 charges in far-field blast events. Experimental results are compared to a series of numerical analyses conducted with different masses of TNT explosive and conclusions are drawn in order to provide a more informed value of TNTeq. It is found that a TNTeq of 1.2 best describes the blast waves produced from PE4 detonations, and this factor is found to be invariant of the distance from the explosive when considering far-field events.

7

An assessment of reliability of a blast wall using limited statistical information on blast loading

Vaidogas E. R., Kisežauskien L., Juocevičius V.

Journal of Polish Safety and Reliability Association

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2013

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Vol. 4, No. 2

259--266

EN

A design of a blast wall is considered. Methods of structural reliability analysis and quantitative risk assessment are applied to the design. The basic idea of this design is to apply a probability of failure of cladding components as a criterion of damage to the cladding. This probability is used as an estimate of the proportion of cladding components destroyed by an explosion. The cladding failure probability is estimated by quantifying and propagating uncertainties related to a mechanical model of cladding and elements of the statistical sample containing records of blast loading. It is demonstrated how to estimate the cladding failure probability when the size of this sample is small from the standpoint of classical statistics. The case study included in the paper considers a design of a cladding for a blast wall to be deployed for protecting a fuel tank against an explosion of a railroad tank car.

8

Numerical analysis of blast loaded structure of thin-walled tubes

Dacko A., Cieśla P., Nowak J.

Journal of KONES

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2007

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Vol. 14, No. 1

131-144

EN

The paper presents the problems of modelling cylindrical specimens, loaded by pressure wave from the blast of explosive charge. The numerical simulation was performed using MSC.Dytran. The cylindrical specimen, along with top and bottom disks is modelled using solid elements. The influence of chosen parameters on the deformation process was investigated. That included material models, hourglass energy damping, rigid/deformable base models and cylinder -top disk connection model (contact/weld). The test rig was setup in numerical model. It consisted of rigid base and the base plate resting on it. The model of set of five energy absorbing cylinders was created. The load was modelled by applying a varying pressure to the top cover of the set. The pressure was applied to the whole top cover or to the chosen area in the middle of the top cover. The results of numerical simulation were compared to the results of experiments. In the case of load applied to the part of top cover, the deformation shape for numerical model was matching he real deformation of the structure.

PL

W pracy przedstawiono problematyką modelowania elementów cylindrycznych obciążonych falą ciśnienia powstałą w wyniku detonacji ładunku materiału wybuchowego. Symulację numeryczną przeprowadzono w środowisku programu MSC Dytran. Do tworzenia modeli numerycznych cylindra, górnej pokrywy oraz podstawy użyto elementów bryłowych typu Solid. Rozpatrywano wpływ następujących parametrów na proces deformacji elementu cylindrycznego: model materiału, tłumienie energii hourglass, wprowadzenie odkształcalnej podstawy oraz połączenie cylindra i pokrywy za pomocą lutu. Utworzono model numeryczny stanowiska do badań pakietów elementów cylindrycznych składającego się z nieodkształcalnej podstawy i przymocowanej do niej płyty bazowej. Stworzono model pakietu elementów energochłonnych składający się z pięciu cylindrów. Obciążenie realizowano poprzez przyłożenie zmiennego w czasie ciśnienia do pokrywy górnej pakietu. Rozpatrzono przypadki obciążenia falą jednorodną rozłożoną na całym obszarze górnej pokrywy oraz falą ciśnienia działającą na wybrany obszar w środkowej części pokrywy. Wyniki obliczeń porównano z wynikami otrzymanymi na drodze eksperymentalnej. W drugim przypadku uzyskano zgodność postaci deformacji modelu numerycznego i konstrukcji rzeczywistej.

9

Experimental tests of blast loaded thin-walled tubes

Dacko M., Nowak J., Dacko A.

Journal of KONES

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2007

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Vol. 14, No. 1

155-162

PL

W pracy przedstawiono stanowisko do badań cylindrycznych elementów cienkościennych obciążonych impulsem wybuchu. Głównym celem badań było określenie parametrów impulsu obciążenia tj. czasu trwania i maksymalnej wartości siły. Obciążenie realizowano detonacją niewielkich ładunków materiału wybuchowego. Do pomiaru siły działającej na powłoką cylindryczną zastosowano czujnik piezoelektryczny. Rejestrację i zapis siły dokonano przy użyciu oscyloskopu cyfrowego. Jako materiał wybuchowy zastosowano plastyczny materiał wybuchowy PMW-14. Ładunki w kształcie cylindrycznym o małej wysokości detonowano przy użyciu zapalników typu Erg. Przeprowadzono pomiar siły działającej na czujnik dla wybuchu ładunku MW umieszczonego w powietrzu w odległości 150 i 200mm od czujnika oraz dla ładunku umieszczonego na badanym elemencie. Oddziaływanie fali wybuchu na element cylindryczny realizowano w układzie: badany element, krążek przykrywający, warstwa dystansowa (15mm styropianu), ładunek wybuchowy. Realizowano dwa typu warunków brzegowych w połączeniu pomiędzy powłoką a krążkiem. W pierwszym występował swobodny kontakt pomiędzy badaną rurką a płytką przykrywającą. W drugim zaś krążek z rurką połączono spoiną pachwinową. Określono masę ładunku niezbędną do zniszczenia elementu cylindrycznego. Przedstawiono wykresy zmienności w czasie siły działającej na czujnik w przypadku wybuchu powietrznego i wybuchu działającego na cylindryczny element energochłonny. Porównano postacie deformacji badanych próbek przy obciążeniach dynamicznych z próbkami poddanymi statycznemu ściskania na maszynach wytrzymałościowych.

EN

The paper presents the stand for experimental investigation of cylindrical specimens, loaded by the pressure wave of the blast. The key parameters determined in experiment were the duration and the peak value of the load. The blast load was generated by detonation of small explosive charges of PWM-14. The force was measured using piezoelectric gauge and registered by digital oscilloscope. The load acting on the gauge was generated by detonation of the charge situated 150 mm and 200 mm from the gauge and the charge situated just on the cylindrical specimen. The pressure blast wave was transmitted to the specimen using a typical setup: the specimen, covering disk, distance layer (15 mm of Styrofoam), explosive charge. The specimen and the covering disc were either just in contact or were soldered. The explosive charge mass, necessary to crush the specimen, was measured. The time variation of the gauge load was monitored for both aerial explosion, as well as explosion acting directly on the specimen. The deformation shape of crushed energy absorbing elements was compared for dynamic loads and static loads in testing machines.

10

Experimental studies of blast loaded structure of thin-walled tubes

Dacko M., Kiczko A., Nowak J., Dacko A., Cieśla P.

Journal of KONES

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2007

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Vol. 14, No. 1

145-154

EN

The paper presents the custom design of the add-on shield, consisting of the set of cylindrical tube elements, protecting the main structure against the effect of the explosive blast pressure load. The experimental stand was designed and set up, allowing tests of protective structures loaded with pressure blast wave. The key parameter measured in experiments was the influence of protective shield on the deformation of protected structures under blast load. The deformation and strain in the protected plates was measured using strain gauges (ESAM Traveler bridge) with 100 000 Hz sampling. The PWM-14 explosives were used. Three groups of experiments were performed. In the first one the plate is directly loaded by the blast pressure wave originating from explosion in some distance from the plate. In the second type a single energy absorbing element is used on the plate, while in the third - a set of 4 or 5 energy absorbing elements is used on the plate, loaded by blast wave of explosion of 30-50 g charge. The plate deflection magnitude and the deformation shape of energy absorbing elements were compared for successive groups of experiments.

PL

W pracy przedstawiono zaproponowane przez autorów rozwiązanie warstwy ochronnej - w postaci pakietu elementów cylindrycznych - zabezpieczającej konstrukcję przed skutkami eksplozji ładunku materiału wybuchowego. Omówiono projekt i wykonano stanowiska do badania płyt z warstwą ochronną obciążonych impulsem wybuchu. Głównym celem badań było określenie efektywności proponowanego rozwiązania poprzez określenie wpływu zastosowania warstwy ochronnej na odkształcenie płyty powstałe w wyniku detonacji ładunku MW. Pomiar odkształcenia i ugięcia płyty realizowano metodą elektrorezystancyjną przy użyciu mostka tensometrycznego ESAM Traveller. Zapis wyników odbywał się z częstotliwością 100 000 Hz. Jako materiał wybuchowy zastosowano plastyczny materiał wybuchowy PMW-14. W programie badań zrealizowano trzy rodzaje eksperymentów. Pierwszą grupę stanowiły badania, w których detonacja ładunku wybuchowego odbywała się w pewnej odległości od badanej płyty a powstała w wyniku detonacji fala nadciśnienia oddziałuje bezpośrednio na płytę. Drugą grupę badań stanowią eksperymenty z pojedynczym elementem energochłonnym i detonacją ładunku w pewnej odległości od niego. Trzecią grupę badań stanowiły eksperymenty z udziałem pakietów cztero- i pięcioelementowych poddanych działaniu ładunków o masie 30-50 gramów. Porównano wielkość deformacji płyty dla poszczególnych przypadków oraz postacie deformacji pojedynczych elementów i pakietów elementów energochłonnych.