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Bei der Detonation einer Sprengladung unter dem Boden eines Fahrzeugs, z. B. einer vergrabenen Mine oder eines improvisierten Sprengkörpers, treten zwei Haupteffekte auf: die Verformung oder Zerstörung des Fahrzeugbodens durch die vom Blast übertragene Belastung und die allgemeine vertikale Beschleunigung des Fahrzeugs. Diese kann aufgrund des auf das Fahrzeug übertragenen Impulses zu einem Überschlag führen. Viele Studien über Fahrzeugschutz in der einschlägigen Literatur befassen sich mit der Übertragung der Belastung und haben zum Ziel, die Verformung des Fahrzeugbodens zu verringern. Es befassen sich aber nur sehr wenige Studien mit der Übertragung des Impulses und damit der Änderung des Bewegungsmoments. Die Verwendung von Flüssigkeiten, insbesondere Wasser, wurde als potenzielles Mittel zur Beeinflussung der Impulsübertragung identifiziert. Die wenigen in der Literatur vorhandenen Studien konzentrieren sich jedoch auf die Wirkungen des Vorhandenseins von Wasser innerhalb der Schutzstruktur. Sie bewerten die Reduzierung des auf das Ziel übertragenen Impulses im Hinblick auf den Verformungsgrad des Ziels. Diese Arbeit hat zum Ziel, die in der Flüssigkeit stattfindenden Phänomene zu identifizieren, die sich auf die Impulsübertragung auswirken. Dafür wird also vor dem Ziel gemessen. Es wurden experimentelle Studien durchgeführt, bei denen ein Explosivstoff enthaltendes Stoßrohr einen Blast überträgt, welcher der Stoßwelle einer vergrabender Mine nahe kommt. Dabei wird der Blast auf einen mit Wasser gefüllten Behälter übertragen. Diese experimentellen Studien wurden durch numerische Simulationen ergänzt, wodurch einige Einschränkungen, wie die Anzahl der Messpunkte, überwunden werden konnten. Es wurde gezeigt, dass die Verwendung einer Flüssigkeit in einer Schutzstruktur gegen Druckwellen zu einer Ausbreitung des Impulses und damit zu einer lokalen Abnahme des Impulses führt. Es wurde ein Zusammenhang zwischen der freien Fläche, aus welcher die Flüssigkeit aus der, Following the detonation of an explosive charge, such as a buried mine or an improvised explosive device, under a vehicle floor, two main effects occur: the rupture or deformation of the vehicle floor due to the loading transmitted by the blast wave and a global vertical acceleration leading in the worst-case scenario to the overturning of the vehicle, due to the impulse being transmitted. For protection purposes, numerous studies have been conducted in literature regarding load transmission in order to reduce target deformation but very few studies focus on impulse transmission, and thus change in momentum. The use of fluids, and in particular water, has been identified as a possible means on acting on impulse transmission. However, the few studies available in the literature focus on the effects of water being included in the protective structure. Therefore, they evaluate the reduction in transmitted impulse to a target by its reduction in deformation. The aim of this work is to identify the phenomena taking place in the fluid itself acting on impulse transmission, placing the investigation upstream of a potential target. Experimental investigations using an explosive driven shock tube allowing the transmission of a blast wave similar to that of a buried mine to a fluid filled container were carried out. These experimental studies were supplemented by numerical simulations, allowing to overcome certain limitations such as the number of measuring points. It was shown that the use of a fluid in a protection against the effects of blast allows the impulse to be spread out, and therefore its local reduction. A link was established between the free surface allowing the fluid to be ejected out of the protection and this impulse spreading. For a more global comprehension of the phenomenon, a blast pendulum was used to observe the effects of fluid filled protection on momentum. This second experimental setup was used to study the effect of the direction of fluid ejection

This master's thesis is focused on the structural response due to blast loading, where the geometry used was arbitrary but heavily inspired by Siemens Energy. The aim of the thesis is to gain a better understanding on how to model the blast load and how it affects the structure, as well as to study the modeling of bolts with both pre-tension and a damage criteria in an explicit analysis. Lastly, the importance of strain rate dependent material models was studied. Other aspects such as mass scaling and Rayleigh damping were also investigated. The software used to solve these tasks were Hypermesh, Abaqus and Python. To conclude, the conclusions drawn from this thesis was that bolts should be modeled using connector elements, and including pre-tension is more conservative than not using it for the case studied. However, for the material modeling it gives more conservative results when using a strain rate independent material model compared to the strain rate dependent model, and is advised to be used in the future.

This master's thesis is focused on the structural response due to blast loading, where the geometry used was arbitrary but heavily inspired by Siemens Energy. The aim of the thesis is to gain a better understanding on how to model the blast load and how it affects the structure, as well as to study the modeling of bolts with both pre-tension and a damage criteria in an explicit analysis. Lastly, the importance of strain rate dependent material models was studied. Other aspects such as mass scaling and Rayleigh damping were also investigated. The software used to solve these tasks were Hypermesh, Abaqus and Python. To conclude, the conclusions drawn from this thesis was that bolts should be modeled using connector elements, and including pre-tension is more conservative than not using it for the case studied. However, for the material modeling it gives more conservative results when using a strain rate independent material model compared to the strain rate dependent model, and is advised to be used in the future.

The risk of exposure of civil and military infrastructures to blast load is increasing due to escalating deliberate and accidental explosions around the globe. To limit and prevent structural damage and collapse from blast loading, specialised protection systems are required to be employed. Therefore, the use of lightweight, high-performance, and smart structures is extremely important for efficient protection against explosions. Auxetic structures, a class of structural metamaterial with a negative Poisson’s ratio, are one such structure exhibiting a high potential for protective applications. With their counterintuitive deformation mechanism, auxetic structures draw materials towards the impact zone, which leads to increased energy absorption, enhanced indentation resistance, and improved fracture toughness. Therefore, this research aimed to develop novel lightweight, high-energy absorbing auxetic structures and implement them to protect infrastructures against blast loading. This work developed three novel lightweight, high-energy absorbing auxetic structures using a density-based topology optimisation method. The developed novel auxetic structures were named the hourglass structure (HGS), braced cross-petal structure (BCPS), and cross-petal structure (CPS). The preliminary protective performance of the developed auxetic structures were assessed through the in-plane compression behaviour simulated in LS-DYNA finite element program. Based on the selected protective performance indicators—the peak elastic stress, plateaus stress, onset of the densification strain, and specific energy absorption (SEA), the HGS outperformed the other new structures and conventional auxetic structures. Therefore, the HGS was selected for further investigation in this research. To further study the protective performance comprehensively, the HGS was 3D printed through the fused filament fabrication technique. The fabricated specimens were subjected to quasi-static uniaxial compression.

With the rise of hydrogen as a green alternative for fossil fuels, the demand for storage capacity of hydrogen increases significantly. Due to the high risk of explosions in urban environments it brings along, the blast analysis of buildings within in range of the explosions becomes more relevant. The goal of this research is to develop a quick method to analyse the roof of a building subjected to blast load. This is done by first clarifying the blast load definition on a reinforced concrete (RC) structural element through existing design standards and literature. Next, the material behaviour of the concrete and the reinforcement steel is scrutinised by an extensive literature study. Materials behave differently under dynamic loads. The dynamic material properties are increased by the strength increase factor (SIF) and the dynamic increase factor (DIF). In blast analysis, most energy is dissipated though plastic deformation. Therefore, it is of great importance to accurately describe the nonlinear behaviour of RC elements. The nonlinear behaviour of RC elements is translated in the moment-curvature relationship. This relationship is calculated on cross-sectional level and serves as input for the global beam or slab model. The global structural behaviour of the beam or the slab is calculated using the finite difference method (FDM). The FDM model generates a force-deflection (F-u) relationship which can be used in the single degree of freedom (SDOF) mass-spring system. The SDOF mass-spring system is used in this research to predict the dynamic behaviour of RC elements. The research method is validated by published experiments and finite element analysis. Three experiments are reported, where the following results are obtained: • Flexural stiffness may be assumed when the scaled distance is above 1.2 m/kg1/3. This is labelled as the ‘far field design range’. • When choosing the DIFs carefully, the dynamic behaviour of RC elements can, Annotation dynamics of structures, Civil Engineering | Structural Engineering

With the rise of hydrogen as a green alternative for fossil fuels, the demand for storage capacity of hydrogen increases significantly. Due to the high risk of explosions in urban environments it brings along, the blast analysis of buildings within in range of the explosions becomes more relevant. The goal of this research is to develop a quick method to analyse the roof of a building subjected to blast load. This is done by first clarifying the blast load definition on a reinforced concrete (RC) structural element through existing design standards and literature. Next, the material behaviour of the concrete and the reinforcement steel is scrutinised by an extensive literature study. Materials behave differently under dynamic loads. The dynamic material properties are increased by the strength increase factor (SIF) and the dynamic increase factor (DIF). In blast analysis, most energy is dissipated though plastic deformation. Therefore, it is of great importance to accurately describe the nonlinear behaviour of RC elements. The nonlinear behaviour of RC elements is translated in the moment-curvature relationship. This relationship is calculated on cross-sectional level and serves as input for the global beam or slab model. The global structural behaviour of the beam or the slab is calculated using the finite difference method (FDM). The FDM model generates a force-deflection (F-u) relationship which can be used in the single degree of freedom (SDOF) mass-spring system. The SDOF mass-spring system is used in this research to predict the dynamic behaviour of RC elements. The research method is validated by published experiments and finite element analysis. Three experiments are reported, where the following results are obtained: • Flexural stiffness may be assumed when the scaled distance is above 1.2 m/kg1/3. This is labelled as the ‘far field design range’. • When choosing the DIFs carefully, the dynamic behaviour of RC elements can, Annotation dynamics of structures, Civil Engineering | Structural Engineering

Historical buildings are located in the city center, near squares where celebrations take place. These festivities usually include pyrotechnic events that impose blast loadings on historical buildings. In this paper, a methodology for the analysis of the dynamic response of historical buildings is presented, and applied to the Altamira Palace — a historical building listed as Spanish National Monument located in Elche (Spain) — during the experimental campaigns that registered the effect of two different pyrotechnic events. Vibration levels associated with these events are presented and analysed according to several international standards and scientific recommendations, in order to avoid even cosmetic damages. The qualitative analysis of the accelerograms, registered during both events, served to identify the different parts of the spectacle, in which the highest accelerations were induced during the last phase (commonly known as the earthquake). Based on the quantitative analysis of the signals, the most significant frequency range in terms of possible damage to the monument was detected below 10 Hz. In this range, the measurements showed peak accelerations much higher than those limits recommended in the different standards and scientific reports.

Due to high specific strength and stiffness as well as outstanding energy-absorption characteristics, sandwich structures are extensively used in aircraft, aerospace, automobile, and marine industries. With the objective of finding lightweight blast-resistant sandwich structures for protecting infrastructure, we have found, for a fixed areal mass density, one- or two-core doubly-curved sandwich shell's (plate's) geometries and materials and fiber angles of unidirectional fiber-reinforced face sheets for it to have the maximum first failure load under quasistatic (blast) loads. The analyses employ a third-order shear and normal deformable plate/shell theory (TSNDT), the finite element method (FEM), a stress recovery scheme (SRS), the Tsai-Wu failure criterion and the Nest-Site selection (NeSS) optimization algorithm, and assume the materials to be linearly elastic. For a sandwich shell under the spatially varying static pressure on the top surface, the optimal non-symmetric one-core (two-core) design improves the first failure load by approximately 33% (27%) and 50% (36%) from the corresponding optimal symmetric design with clamped and simply-supported edges, respectively. For a sandwich plate under blast loads, it is found that the optimal one-core design is symmetric about the mid-surface with thick face sheets, and the optimal two-core design has a thin middle face sheet and thick top and bottom face sheets. Furthermore, the transverse shear stresses (in-plane transverse axial stresses) primarily cause the first failure in a core (face sheet). For the computed optimal design under a blast load, we also determined the collapse load by using the progressive failure analysis that degrades all elasticities of the failed material point to very small values. The collapse load of the clamped (simply-supported) sandwich structure is approximately 15%–30% (0%–17%) higher than its first failure load. Incompressible materials such as rubbers, polymers, and soft tissues that

The purpose of this Master thesis is to evaluate the RFEM software and determine if it could be used for dynamic analyses using blast loads from explosions. Determining the blast resistance for a structure is a growing market and would therefore be beneficial for Sweco Eskilstuna if RFEM could be used for this type of work. The verification involved comparing the RFEM software to a real experiment which consisted of a set of blast tested reinforced concrete beams. By using the structural properties from the experiment project with the experiment setup the same structure could be replicated in RFEM. RFEM would then simulate a dynamic analysis loaded with the same dynamic load measured from the experiment project in two different dynamic load cases caused by two differently loaded explosions. The structural response from the experiment could then be compared to the response simulated by the RFEM software, which consisted of displacement- and acceleration time diagrams. By analysing the displacement and acceleration of both the experiment and the RFEM software the accuracy was determined, and how well RFEM preformed the analysis for this specific situation. The comparison of the displacement and acceleration between the experiment and RFEM was considered acceptable if the maximum displacement was consistent with the experiments result and within the same time frame. The acceleration was considered acceptable if the initial acceleration was consistent with the experiment result. These criteria needed to be met for the verification that RFEM could simulate a dynamic analysis. If the software managed to complete a dynamic analysis for two dynamic load cases, then the software could be evaluated which consisted of determining if the post blast effects could be determined and if the modelling method was reliable. The acceleration from RFEM were in good agreement with the experiment test at the initial part of the blast, reaching a close comparison for both load cases after

Due to high specific strength and stiffness as well as outstanding energy-absorption characteristics, sandwich structures are extensively used in aircraft, aerospace, automobile, and marine industries. With the objective of finding lightweight blast-resistant sandwich structures for protecting infrastructure, we have found, for a fixed areal mass density, one- or two-core doubly-curved sandwich shell's (plate's) geometries and materials and fiber angles of unidirectional fiber-reinforced face sheets for it to have the maximum first failure load under quasistatic (blast) loads. The analyses employ a third-order shear and normal deformable plate/shell theory (TSNDT), the finite element method (FEM), a stress recovery scheme (SRS), the Tsai-Wu failure criterion and the Nest-Site selection (NeSS) optimization algorithm, and assume the materials to be linearly elastic. For a sandwich shell under the spatially varying static pressure on the top surface, the optimal non-symmetric one-core (two-core) design improves the first failure load by approximately 33% (27%) and 50% (36%) from the corresponding optimal symmetric design with clamped and simply-supported edges, respectively. For a sandwich plate under blast loads, it is found that the optimal one-core design is symmetric about the mid-surface with thick face sheets, and the optimal two-core design has a thin middle face sheet and thick top and bottom face sheets. Furthermore, the transverse shear stresses (in-plane transverse axial stresses) primarily cause the first failure in a core (face sheet). For the computed optimal design under a blast load, we also determined the collapse load by using the progressive failure analysis that degrades all elasticities of the failed material point to very small values. The collapse load of the clamped (simply-supported) sandwich structure is approximately 15%–30% (0%–17%) higher than its first failure load. Incompressible materials such as rubbers, polymers, and soft tissues that

The purpose of this Master thesis is to evaluate the RFEM software and determine if it could be used for dynamic analyses using blast loads from explosions. Determining the blast resistance for a structure is a growing market and would therefore be beneficial for Sweco Eskilstuna if RFEM could be used for this type of work. The verification involved comparing the RFEM software to a real experiment which consisted of a set of blast tested reinforced concrete beams. By using the structural properties from the experiment project with the experiment setup the same structure could be replicated in RFEM. RFEM would then simulate a dynamic analysis loaded with the same dynamic load measured from the experiment project in two different dynamic load cases caused by two differently loaded explosions. The structural response from the experiment could then be compared to the response simulated by the RFEM software, which consisted of displacement- and acceleration time diagrams. By analysing the displacement and acceleration of both the experiment and the RFEM software the accuracy was determined, and how well RFEM preformed the analysis for this specific situation. The comparison of the displacement and acceleration between the experiment and RFEM was considered acceptable if the maximum displacement was consistent with the experiments result and within the same time frame. The acceleration was considered acceptable if the initial acceleration was consistent with the experiment result. These criteria needed to be met for the verification that RFEM could simulate a dynamic analysis. If the software managed to complete a dynamic analysis for two dynamic load cases, then the software could be evaluated which consisted of determining if the post blast effects could be determined and if the modelling method was reliable. The acceleration from RFEM were in good agreement with the experiment test at the initial part of the blast, reaching a close comparison for both load cases after

Historical buildings are located in the city center, near squares where celebrations take place. These festivities usually include pyrotechnic events that impose blast loadings on historical buildings. In this paper, a methodology for the analysis of the dynamic response of historical buildings is presented, and applied to the Altamira Palace — a historical building listed as Spanish National Monument located in Elche (Spain) — during the experimental campaigns that registered the effect of two different pyrotechnic events. Vibration levels associated with these events are presented and analysed according to several international standards and scientific recommendations, in order to avoid even cosmetic damages. The qualitative analysis of the accelerograms, registered during both events, served to identify the different parts of the spectacle, in which the highest accelerations were induced during the last phase (commonly known as the earthquake). Based on the quantitative analysis of the signals, the most significant frequency range in terms of possible damage to the monument was detected below 10 Hz. In this range, the measurements showed peak accelerations much higher than those limits recommended in the different standards and scientific reports.

Investigating the stress concentration in reinforced concrete connections under the blast loads is the purpose of the present paper. This goal was achieved by the design and analysis of the connections. The finite element package ABAQUS was used in this study to model and analyse the connections. A reinforced concrete connection which was tested experimentally was modelled and analysed in order to verify modelling. The results of modelling and experimental test were compared which demonstrated the accuracy of modelling. Afterwards, two reinforced concrete buildings with five and nine storeys were designed employing the ETABS software. A beam-column connection of the ground floor of each building was designed. The sizes of the cross-sections of the beams and columns and the spaces of their stirrups were considered differently. These connections were also modelled and analysed. The distances of the connections from the blast centre were considered as 2.5 m, 5 m, and 10 m and the blast powers were adopted as 500 kg, 1000 kg, and 2000 kg TNT equivalent mass of explosive for the analyses of the connections. The stresses created in the reinforcements of the connections owing to the blast loads were examined. It was demonstrated that as the connection was located farther from the blast centre, the stresses in the connection reinforcements were reduced. Also, the stresses in the connection reinforcements were increased by enhancing the blast power. Meanwhile, using larger cross-sections for the beam and column in the connection of nine-storey building than the connection of five-storey building transferred the stress concentration in the reinforcements to the beam and near the beam-column connection. By decreasing the stirrups spaces of the beam in the connection of five-storey building, the high stresses in the reinforcements were mainly transferred to the beam of the connection which could reduce the likelihood of the progressive collapse of the structure.

An appropriate stress–strain relationship of geomaterials subjected to blast loading is essential for the design of underground protective structures. Previous experimental and theoretical research efforts indicate that the constitutive behavior of geomaterials under blast loading depends upon strain rate, stress level, and interaction among the three phases (solid, liquid, and gases). In current state-of-the-art, various advanced constitutive models are available to model the stress–strain behavior of geomaterials under blast-loads. However, considering the cost of computation associated with such models, a functional form is discussed to model the loading and unloading branches of stress–strain curve of geomaterials subjected to blast load based on the three parameters: weight factor, initial modulus ratio, and strain recovery ratio. It is observed that the new functional form reasonably captures the mean trend of the experimentally obtained or simulated stress–strain data. This paper further investigates the applicability of this functional form and provides a catalog of the model parameters for direct use by practicing engineers. The dependence of function parameters on strain rate, lateral confinement, degree of saturation, initial compaction, and locking initiation stress is investigated, and some simple rules are proposed for reasonable estimation of the three parameters. The proposed functional form would be quite useful in practical design problems specially where cost of computation associated with advanced constitutive models is too high. In addition to this, the proposed simple parametrization of complex nonlinear stress–strain behavior also provides an opportunity to investigate the effect of uncertainties in soil parameters in a computationally efficient manner., SCOPUS: ar.j, info:eu-repo/semantics/published

We report on the results of dimensional analyses on the dynamic plastic response of square armour steel plates due to detonation of proximal cylindrical charges and ensued air blast loading. By assuming a generic function for the blast load, which is multiplicative comprising its spatial and temporal parts, a set of 14 dimensionless parameters, representative of the load and plate deformation, were identified and recast in the form of dimensionless functions of stand-off to charge diameter ratio. Parametric studies were performed using commercial code ABAQUS’s module of Finite Element hydrocode using MMALE and MMAE techniques, and combined with regression analyses to quantify the dimensional parameters and the expressions for dimensionless functions. A few numerical studies with various FE mesh types were also performed to validate the transient deflections against the small-scale experiments. For pulse loading due to proximal charges of small orders of stand-off/charge diameter ratio, the magnitude of the transverse deflection increased abruptly with incremental decrease in stand-off, in contradistinction to the plate deformations at higher stand-offs where variations in displacement are smooth. This confirmed the existence of a stand-off at which a transition in behaviour takes place. For stand-off values less than charge diameter, a dimensionless energy absorbing effectiveness factor was considered to investigate the prediction of rupture in the plate corresponding to different charge masses. This factor is measured as a baseline parameter to predict, using solely numerical means, the blast loads which ensue rupture on full-scale prototypes.

We report on the results of dimensional analyses on the dynamic plastic response of square armour steel plates due to detonation of proximal cylindrical charges and ensued air blast loading. By assuming a generic function for the blast load, which is multiplicative comprising its spatial and temporal parts, a set of 14 dimensionless parameters, representative of the load and plate deformation, were identified and recast in the form of dimensionless functions of stand-off to charge diameter ratio. Parametric studies were performed using commercial code ABAQUS’s module of Finite Element hydrocode using MMALE and MMAE techniques, and combined with regression analyses to quantify the dimensional parameters and the expressions for dimensionless functions. A few numerical studies with various FE mesh types were also performed to validate the transient deflections against the small-scale experiments. For pulse loading due to proximal charges of small orders of stand-off/charge diameter ratio, the magnitude of the transverse deflection increased abruptly with incremental decrease in stand-off, in contradistinction to the plate deformations at higher stand-offs where variations in displacement are smooth. This confirmed the existence of a stand-off at which a transition in behaviour takes place. For stand-off values less than charge diameter, a dimensionless energy absorbing effectiveness factor was considered to investigate the prediction of rupture in the plate corresponding to different charge masses. This factor is measured as a baseline parameter to predict, using solely numerical means, the blast loads which ensue rupture on full-scale prototypes.

One of the most important examples of transverse excitation of beam-columns is structural reinforced concrete (RC) columns under blast loading. Under accidental or intentional explosions next to the buildings, external columns are the most critical and vulnerable structural elements. In this paper, tow analytical approaches are used to predict the first maximum dynamic response of rectangular RC column under simultaneously effect of axial force and transverse blast loading. The first analytical model is based on continuous formulation of Euler-Bernoulli beam theory and the second model is a single degree of freedom (SDOF) approach. Both of the approaches consider strain rate effects on nonlinear behavior of materials (concrete and steel reinforcement) and secondary effects of P-δ. Results of proposed models for predicting the first maximum lateral response of column under impulsive, dynamic and quasi-static loading regimes are compared to the results of nonlinear finite element analysis. The outcomes indicate undesirable discrepancies under high levels of axial force and quasi-static loading conditions. Nevertheless, in the impulsive and dynamic regimes and moderate and low axial load ratio, the differences in the results are acceptable. Afterward, the analytical models are used to evaluate Pressure-Impulse (P-I) diagram for RC column under blast loading and effective factors on it.

One of the most important examples of transverse excitation of beam-columns is structural reinforced concrete (RC) columns under blast loading. Under accidental or intentional explosions next to the buildings, external columns are the most critical and vulnerable structural elements. In this paper, tow analytical approaches are used to predict the first maximum dynamic response of rectangular RC column under simultaneously effect of axial force and transverse blast loading. The first analytical model is based on continuous formulation of Euler-Bernoulli beam theory and the second model is a single degree of freedom (SDOF) approach. Both of the approaches consider strain rate effects on nonlinear behavior of materials (concrete and steel reinforcement) and secondary effects of P-δ. Results of proposed models for predicting the first maximum lateral response of column under impulsive, dynamic and quasi-static loading regimes are compared to the results of nonlinear finite element analysis. The outcomes indicate undesirable discrepancies under high levels of axial force and quasi-static loading conditions. Nevertheless, in the impulsive and dynamic regimes and moderate and low axial load ratio, the differences in the results are acceptable. Afterward, the analytical models are used to evaluate Pressure-Impulse (P-I) diagram for RC column under blast loading and effective factors on it.

Tato práce se zabývá simulací zkoušky funkčnosti výbuchuvzdorného objektu, která byla provedena Vědeckovýzkumným uhelným ústavem. K výpočtu je použit řešič MSC.Nastran. Bude uvedena i teorie potřebná k výpočtu. V první fázi bude cílem nasimulovat proudění vzduchu tak, aby v místě hrázového objektu byl průběh tlaku shodný s průběhem tlaku naměřeném při experimentu a druhá fáze bude spočívat v aplikaci tohoto proudění na hrázový objekt. Výsledky budou srovnány s dostupnými hodnotami z experimentu., Goal of this thesis is to simulate test of the pressure-resistant object which was performed by the VVUÚ. MSC Nastran was used for the simulation and calculations. This thesis will include theory required for the simulation. First goal is to simulate pressure at pressure-resistant barrier, results needs to be same as the ones obtained by the experiment. Second goal is to apply simulation results of the airflow on the barrier object itself. Results will be compared with available measured values from the experiment., Ve zpracování, Import 23/07/2015

A model of deformation of a metal hollow section beam under a uniform blast loading is developed in order to reveal the characteristic features of deformation and energy absorption of hollow section beams under such loading. It is established that as a typical structural component a hollow section distinguishes itself from its solid counterpart with two characteristic features of the response. First, a considerably larger kinetic energy is generated in the hollow section beam as the impulsive load is imparted on the upper flange of the beam having a significantly lower mass than the member. Second, a considerable proportion of the blast energy can be absorbed by the local collapse of the section. A two-phase analytical model is proposed. In the first phase, the local collapse of the thin-walled cross-section is determined by using an upper bound approach; and in the subsequent second phase, the global bending of the beam with the distorted section is analyzed by taking into account the effect of axial force. It is demonstrated that mass distribution in the hollow section is an important factor in determining the energy partitioning between the local deformation phase and global bending of the hollow beam. Reasonable agreement is obtained with the experimental data published in the literature [Jama HH, Nurick GN, Bambach MR, Grzebieta RH, Zhao XL, Steel square hollow sections subjected to transverse blast loads, Thin-Walled Structures 2012;53:109-122].

This paper illustrates the use of finite element (FE) technique to investigate the behaviour of laminated glass (LG) panels under blast loads. Two and three dimensional (2D and 3D) modelling approaches available in LS-DYNA FE code to model LG panels are presented. Results from the FE analysis for mid-span deflection and principal stresses compared well with those from large deflection plate theory. The FE models are further validated using the results from a free field blast test on a LG panel. It is evident that both 2D and 3D LG models predict the experimental results with reasonable accuracy. The 3D LG models give slightly more accurate results but require considerably more computational time compared to the 2D LG models.

Recently, increasing terrorist threats on bridges have illustrated the vulnerabilities of this type of transportation infrastructure. Because of cost and safety constraints, it is impractical to obtain the complete structural response by testing a real bridge, so in recent years, a fully coupled fluid-structure interaction model, which still has several assumptions, was developed to simulate the blast wave propagation process and its interaction with the structure; this has become an advanced method to better analyze blast loading effects. However, because of the complicated computational algorithm and desktop computer resource limitations involved in using this model, it is not practical to simulate large structural responses, especially for long-span bridges. The purpose of this paper is to develop a multi-Euler domain method to solve the problems listed earlier. Both the verification of the method and its application for a RC composite slab-on-girder bridge proved its accuracy and efficiency. The blast-resistant capacity of three different detonation scenarios was investigated, including one above-deck detonation and two under-deck detonations, with different trinitrotoluene (TNT)-equivalent charge weights. This study established the dynamic performance and the damage mechanisms of the whole bridge and identified the critical blast event for this typical slab-on-girder bridge. The results and observations of this study provide a global understanding of protection strategies for highway bridges. © 2013 American Society of Civil Engineers.

A model of deformation of a metal hollow section beam under a uniform blast loading is developed in order to reveal the characteristic features of deformation and energy absorption of hollow section beams under such loading. It is established that as a typical structural component a hollow section distinguishes itself from its solid counterpart with two characteristic features of the response. First, a considerably larger kinetic energy is generated in the hollow section beam as the impulsive load is imparted on the upper flange of the beam having a significantly lower mass than the member. Second, a considerable proportion of the blast energy can be absorbed by the local collapse of the section. A two-phase analytical model is proposed. In the first phase, the local collapse of the thin-walled cross-section is determined by using an upper bound approach; and in the subsequent second phase, the global bending of the beam with the distorted section is analyzed by taking into account the effect of axial force. It is demonstrated that mass distribution in the hollow section is an important factor in determining the energy partitioning between the local deformation phase and global bending of the hollow beam. Reasonable agreement is obtained with the experimental data published in the literature [Jama HH, Nurick GN, Bambach MR, Grzebieta RH, Zhao XL, Steel square hollow sections subjected to transverse blast loads, Thin-Walled Structures 2012;53:109-122].

Recently, increasing terrorist threats on bridges have illustrated the vulnerabilities of this type of transportation infrastructure. Because of cost and safety constraints, it is impractical to obtain the complete structural response by testing a real bridge, so in recent years, a fully coupled fluid-structure interaction model, which still has several assumptions, was developed to simulate the blast wave propagation process and its interaction with the structure; this has become an advanced method to better analyze blast loading effects. However, because of the complicated computational algorithm and desktop computer resource limitations involved in using this model, it is not practical to simulate large structural responses, especially for long-span bridges. The purpose of this paper is to develop a multi-Euler domain method to solve the problems listed earlier. Both the verification of the method and its application for a RC composite slab-on-girder bridge proved its accuracy and efficiency. The blast-resistant capacity of three different detonation scenarios was investigated, including one above-deck detonation and two under-deck detonations, with different trinitrotoluene (TNT)-equivalent charge weights. This study established the dynamic performance and the damage mechanisms of the whole bridge and identified the critical blast event for this typical slab-on-girder bridge. The results and observations of this study provide a global understanding of protection strategies for highway bridges. © 2013 American Society of Civil Engineers.

Recently, increasing terrorist threats on bridges have illustrated the vulnerabilities of this type of transportation infrastructure. Because of cost and safety constraints, it is impractical to obtain the complete structural response by testing a real bridge, so in recent years, a fully coupled fluid-structure interaction model, which still has several assumptions, was developed to simulate the blast wave propagation process and its interaction with the structure; this has become an advanced method to better analyze blast loading effects. However, because of the complicated computational algorithm and desktop computer resource limitations involved in using this model, it is not practical to simulate large structural responses, especially for long-span bridges. The purpose of this paper is to develop a multi-Euler domain method to solve the problems listed earlier. Both the verification of the method and its application for a RC composite slab-on-girder bridge proved its accuracy and efficiency. The blast-resistant capacity of three different detonation scenarios was investigated, including one above-deck detonation and two under-deck detonations, with different trinitrotoluene (TNT)-equivalent charge weights. This study established the dynamic performance and the damage mechanisms of the whole bridge and identified the critical blast event for this typical slab-on-girder bridge. The results and observations of this study provide a global understanding of protection strategies for highway bridges. © 2013 American Society of Civil Engineers.

The flexural response and failure of reinforced concrete rectangular slabs subjected to blast loading are investigated based on the rigid-plastic modelling. The effects of orthotropic reinforcement and asymmetric support bending restraints are incorporated to account for structural configurations and detailing. Two schemes of failure pattern are introduced and features of dynamic response under typical blast loading are outlined. Numerical studies are carried out and the results obtained from the present model and explicit finite element simulations are compared. It is shown that the proposed analysis is capable of capturing the essential features of dynamic response of reinforced concrete slabs and provides a simple and efficient means for blast design and assessment of concrete slabs.

The flexural response and failure of reinforced concrete rectangular slabs subjected to blast loading are investigated based on the rigid-plastic modelling. The effects of orthotropic reinforcement and asymmetric support bending restraints are incorporated to account for structural configurations and detailing. Two schemes of failure pattern are introduced and features of dynamic response under typical blast loading are outlined. Numerical studies are carried out and the results obtained from the present model and explicit finite element simulations are compared. It is shown that the proposed analysis is capable of capturing the essential features of dynamic response of reinforced concrete slabs and provides a simple and efficient means for blast design and assessment of concrete slabs.

The transient response of various plate structures subject to blast loads is analyzed. In particular, simply supported isotropic and laminated composite plates are modeled using the commercial finite element code NASTRAN and the method of modal superposition. Both analysis procedures are used to quantify the linear transient response of such plates subject to uniform and patch blast loads. Furthermore, NASTRAN is used to study the nonlinear response of plates subject to close proximity explosions. Also considered here is the case for which a blast loaded plate impacts another closely neighboring plate. The NASTRAN solution used here accounts for nonlinearities due to large plate deflections, plasticity, and plate-to-plate contact. Many studies are currently available in which the blast load is considered to be spatially uniform across the plate; with a temporal distribution described by step, N-pulse, or Friedlander equations. The novel aspect considered here is the case for which the blast pressure is due to a close proximity explosion, and it is therefore taken to be both spatially and temporally varying. A FORTRAN program is described which automates the application of an arbitrary blast load to a generic finite element mesh. The results presented here are a collection of analyses performed for a variety of parameters important to the dynamic response of blast loaded contacting plates. Conclusions are drawn concerning the influence of the various parameters on the nature of the plate response and the quality of the solution.

In this paper a test method to determine the deformation capacity and the resistance-deformation curve of blast-loaded slabs is described. This method was developed at TNO-PML. The method has been used to determine the ultimate deformation capacity of some simply supported reinforced concrete slabs in order to increase the knowledge of this parameter. The influence of the following parameters on the dynamic deformation capacity has been studied: the thickness of the slab, the amount of bending reinforcement and the diameter of the bending reinforcement. Preliminary results have been obtained.