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AbstractThis study investigates the dynamic response of masonry bridges under blast-induced shock waves, focusing on the structural integrity and safety of these critical infrastructure components under extreme conditions. The research employs theoretical approaches to analyze the effects of blast-induced shock waves on masonry bridge structures. A comprehensive numerical simulation framework is developed using finite element analysis (FEA) to model the dynamic interactions between blast waves and the masonry materials. Key parameters, including the blast load intensity, duration, and distance from the blast source, are varied to assess their impact on bridge performance. The results reveal significant insights into the deformation patterns, stress distribution, and potential failure modes of masonry bridges under blast loading scenarios. The findings underscore the importance of incorporating blast resistance measures in the design and retrofitting of masonry bridges to enhance their resilience against explosive events. This study contributes to the advancement of safety standards and design guidelines for masonry bridge structures in the context of blast loading, providing valuable information for engineers, policymakers, and infrastructure managers. [ABSTRACT FROM AUTHOR]

When designing structures to withstand explosions, the main goals are to minimize the number and extent of occupant injuries and to reduce the chance of catastrophic damage to structures. Although there is uncertainty in the source, extent, and location of explosions, the assessment of blast loading and structural performance is important when designing blast-resistant structures. This study is a review of the literature on the prediction of blast loads, structural modeling and analysis, and design criteria for structures to resist explosions. The paper provides in one concise document the general guidelines, references, and tools that structural engineers and researchers need to analyze and design structures subjected to blast loading. References on the topics discussed in this work are provided for more detail.

Protecting important buildings and preserving human lives is an essential requirement in present era as explosions represent a real danger which must be confronted. Current study analyzes the behavior of different eight (8) reinforced concrete barriers subjected to blast loads. The models are divided into barriers anchored in the base and barriers with a base embedded into soil. In addition, the models feature different geometries as there are concave barriers with front angles 49° and 58°. Also, different weights of TNT charges 450 kg, and 1800 kg are used. The study concluded that anchored barriers subjected to TNT charge of 450 kg, barriers with a front angle 49° have the best performance in terms of the pressure values behind the barrier. These barriers have approximately 61% lower pressure values at the center point of barrier back compared to other types of barriers. The best performance is for barrier with front angle 58° in case of TNT charge weighted 1800 kg. These barriers have approximately 41% lower pressure values at the bottom point of the barrier back compared to other types of barriers. In case of embedded barriers, the performance of barriers having front angle 58° is better than the other barriers in case of TNT charge of 450 kg. These barriers have approximately 49% lower pressure values at the center point of barrier back compared to other types of barriers. In case of TNT charge of 1800 kg the best performance was for barriers having front angle 58°. These barriers have approximately 52% lower pressure values at the center point of barrier back compared to other types of barriers. Overall, the embedded barriers demonstrate a better performance rather than the anchored barriers across all TNT charges from pressure values behind the barrier perspective. [ABSTRACT FROM AUTHOR]

A critical challenge of any blast simulation facility is in producing the widest possible pressure-impulse range for matching against equivalent high-explosive events. Shock tubes and blast simulators are often constrained with the lack of effective ways to control blast wave profiles and as a result have a limited performance range. Some wave shaping techniques employed in some facilities are reviewed but often necessitate extensive geometric modifications, inadvertently cause flow anomalies, and/or are only applicable under very specific configurations. This paper investigates controlled venting as an expedient way for waveforms to be tuned without requiring extensive modifications to the driver or existing geometry and could be widely applied by existing and future blast simulation and shock tube facilities. The use of controlled venting is demonstrated experimentally using the Advanced Blast Simulator (shock tube) at the Australian National Facility of Physical Blast Simulation and via numerical flow simulations with Computational Fluid Dynamics. Controlled venting is determined as an effective method for mitigating the impact of re-reflected waves within the blast simulator. This control method also allows for the adjustment of parameters such as tuning the peak overpressure, the positive phase duration, and modifying the magnitude of the negative phase and the secondary shock of the blast waves. This paper is concluded with an illustration of the potential expanded performance range of the Australian blast simulation facility when controlled venting for blast waveform tailoring as presented in this paper is applied. [ABSTRACT FROM AUTHOR]

Structures subjected to explosive loading have become a reality in recent years. With the advent of wars and terrorists’ attacks around the world, it has become extremely necessary to understand the behavior of civil engineering structures as to resist such extreme loads. In this way, the DYNAblast 1.0 software needed to be updated to include another equation to characterize the explosion, the extended positive phase, as well as allowing the user to manipulate the distance between the explosive source and the target as an input data, thus making DYNAblast 1.1 a more complete software.

This study investigates blast dynamics of prestressed segmented columns assembled of osteomorphic interlocking elastic blocks without any binding materials or mechanical connectors. The unique ability of the interlocking structures to absorb and dissipate energy through the independent movement of their segments is analyzed using the nonlinear finite element method. The effects of the number of blocks, the axial prestress, the friction, and the level of interlocking between the contact surfaces on the flexural response and energy absorption capability of the segmented column are investigated parametrically. It is demonstrated that the detachments between blocks control the energy absorption capability of these structures. Therefore, the number of blocks, the axial prestress, and the level of interlocking (i.e., the parameters influencing the available detachment between blocks) define the response of this column to blast loads. Columns segmented into a greater number of blocks with lower prestress levels exhibit a higher damping capability but reduced column stiffness, which is usually undesirable in structural applications. A higher level of interlocking between the contact surfaces of blocks increases the damping capacity of the column without reducing its stiffness. The effect of friction is found to be insignificant for all cases considered. The effect of interlocking is small relative to the effects of prestress and the number of blocks. However, it provides an independent design parameter for the passive mitigation of blast loads. [ABSTRACT FROM AUTHOR]

An explosion on the ground surface can cause considerable damage to underground structures. In this study, a series of experimental and numerical investigations were conducted to examine the performance and reinforcing mechanism of reinforced soil subjected to blast loads. An excavated pit backfilled with sand only (unreinforced soil) and sand reinforced with three layers of geotextiles (reinforced soil) were used as test models in a field explosion test. In the field explosion test, blast pressures in air and soil, ground deformation, and mobilized reinforcement tensile strain were measured. The test results obtained for the reinforced and unreinforced soil were compared to evaluate the effectiveness of using soil reinforcement as a protective barrier against blast loads. The test results indicated that peak blast pressure in the reinforced soil was only 10–28% of those in the unreinforced soil. Two reinforcing mechanisms were identified in this study: the tensioned membrane effect and lateral restraint effect. Moreover, a series of numerical analyses were performed to evaluate the effects of reinforcement parameters on the blast pressure. This study provides useful insights into the application and design of soil reinforcement as an alternative antiexplosion measure to protect underground structures against surface explosions. [ABSTRACT FROM AUTHOR]

The nonlinear dynamic response of magnetoelectroelastic (MEE) functionally graded plates (MEEFG) subjected to blast loads and operating in a temperature environment is examined in this study. The goal of this research is to investigate the impact of pyrocoupling along with the blast loads on the coupled nonlinear behavior of smart MEEFG plates. The material properties of MEEFG plates are calculated using the well-known modified power law. The kinematics of the plate is supposed to follow Reddy's higher-order shear deformation theory (HSDT). Also, von-Karman's equations are used to bring nonlinearity into the model. The blast loads are calculated using an exponential function and are expected to be dispersed evenly across the plate's surface. The principle of virtual work is used to develop the governing equations using finite element (FE) methods, which is then solved using the direct iterative technique. The numerical examples are offered to show how gradient patterns, gradient index, and blast loading parameters affect the nonlinear dynamic response. [ABSTRACT FROM AUTHOR]

This paper presents a time-efficient numerical approach to modelling high explosive (HE) blastwave propagation using Computational Fluid Dynamics (CFD). One of the main issues of using conventional CFD modelling in high explosive simulations is the ability to accurately define the initial blastwave properties that arise from the ignition and consequent explosion. Specialised codes often employ Jones-Wilkins-Lee (JWL) or similar equation of state (EOS) to simulate blasts. However, most available CFD codes are limited in terms of EOS modelling. They are restrictive to the Ideal Gas Law (IGL) for compressible flows, which is generally unsuitable for blast simulations. To this end, this paper presents a numerical approach to simulate blastwave propagation for any generic CFD code using the IGL EOS. A new method known as the Input Cavity Method (ICM) is defined where input conditions of the high explosives are given in the form of pressure, velocity and temperature time-history curves. These time history curves are input at a certain distance from the centre of the charge. It is shown that the ICM numerical method can accurately predict over-pressure and impulse time history at measured locations for the incident, reflective and complex multiple reflection scenarios with high numerical accuracy compared to experimental measurements. The ICM is compared to the Pressure Bubble Method (PBM), a common approach to replicating initial conditions for a high explosive in Finite Volume modelling. It is shown that the ICM outperforms the PBM on multiple fronts, such as peak values and overall overpressure curve shape. Finally, the paper also presents the importance of choosing an appropriate solver between the Pressure Based Solver (PBS) and Density-Based Solver (DBS) and provides the advantages and disadvantages of either choice. In general, it is shown that the PBS can resolve and capture the interactions of blastwaves to a higher degree of resolution than the DBS. This is achieved at a much higher computational cost, showing that the DBS is much preferred for quick turnarounds.

In current guidelines, the free air blast loads (overpressure and impulse) are determined by spherical charges, although most of ordnance devices are more nearly cylindrical than spherical in geometry. This may result in a great underestimation of blast loads in the near field and lead to an unsafe design. However, there is still a lack of systematic quantitative analysis of the blast loads generated from cylindrical charges. In this study, a numerical model is developed by using the hydrocode AUTODYN to investigate the influences of aspect ratio and orientation on the free air blast loads generated from center-initiated cylindrical charges. This is done by examining the pressure contours, the peak overpressures and impulses for various aspect ratios ranged from 1 to 8 and arbitrary orientation monitored along every azimuth angle with an interval of 5°. To characterize the distribution patterns of blast loads, three regions, i.e., the axial region, the vertex region and the radial region are identified, and the propagation of blast waves in each region is analyzed in detail. The complexity of blast loads of cylindrical charges is found to result from the bridge wave and its interaction with primary waves. Several empirical formulas are presented based on curve-fitting the numerical data, including the orientation where the maximum peak overpressure emerges, the critical scaled distance beyond which the charge shape effect could be neglected and blast loads with varied aspect ratio in arbitrary orientation, all of which are useful for blast-resistant design.

Aspects of mathematical and physical modeling of deflagration explosions emerging during atmospheric (outdoor) accidental explosions are addressed. It has been demonstrated that when physically modeling accidental deflagration explosions, a stoichiometric mixture in the shape of a sphere or hemisphere supported by the ground should be used. This allows us to research the parameters of blast loads for the worst-case accidental scenarios or address the accident using the most conservative approach. A technique has been provided allowing one to create a mixture of a given blend composition in the shape of a sphere or hemisphere supported by the ground in outdoor conditions. It has been demonstrated that there is an ability to conduct modeling studies of accidental atmospheric explosions. We have provided examples of modeling studies of accidental atmospheric explosions; a methodology for analyzing experimental results has also been reviewed. The article discusses the mathematical modeling of outdoor (unobstructed) accidental deflagration explosions. It has been demonstrated that it is most reasonable to base computational experiments on linearized (acoustic) equations of continuum motion, as the visible flame propagation rate emerging during explosive combustion is small (compared to the speed of sound). There has been a satisfactory agreement between the numerical analysis and the experimental data. [ABSTRACT FROM AUTHOR]

This paper presents a time-efficient numerical approach to modelling high explosive (HE) blastwave propagation using Computational Fluid Dynamics (CFD). One of the main issues of using conventional CFD modelling in high explosive simulations is the ability to accurately define the initial blastwave properties that arise from the ignition and consequent explosion. Specialised codes often employ Jones-Wilkins-Lee (JWL) or similar equation of state (EOS) to simulate blasts. However, most available CFD codes are limited in terms of EOS modelling. They are restrictive to the Ideal Gas Law (IGL) for compressible flows, which is generally unsuitable for blast simulations. To this end, this paper presents a numerical approach to simulate blastwave propagation for any generic CFD code using the IGL EOS. A new method known as the Input Cavity Method (ICM) is defined where input conditions of the high explosives are given in the form of pressure, velocity and temperature time-history curves. These time history curves are input at a certain distance from the centre of the charge. It is shown that the ICM numerical method can accurately predict over-pressure and impulse time history at measured locations for the incident, reflective and complex multiple reflection scenarios with high numerical accuracy compared to experimental measurements. The ICM is compared to the Pressure Bubble Method (PBM), a common approach to replicating initial conditions for a high explosive in Finite Volume modelling. It is shown that the ICM outperforms the PBM on multiple fronts, such as peak values and overall overpressure curve shape. Finally, the paper also presents the importance of choosing an appropriate solver between the Pressure Based Solver (PBS) and Density-Based Solver (DBS) and provides the advantages and disadvantages of either choice. In general, it is shown that the PBS can resolve and capture the interactions of blastwaves to a higher degree of resolution than the DBS. This is achieved at a much higher computational cost, showing that the DBS is much preferred for quick turnarounds. [ABSTRACT FROM AUTHOR]

A combined experimental and analytical investigation was conducted at the University of Ottawa to assess the performance of blast-resistant window retention anchors to generate design information. The experimental phase of research involved 46 full-scale window tests with different parameters. The analytical investigation included numerical modeling and dynamic analysis of windows to expand the experimental results and to assess the significance of design parameters. Computer software LS-DYNA was selected for the analyses. Analytical models of selected test windows with aspect ratios of 1.0 and 3.0 anchored on structural steel, reinforced concrete, concrete block masonry, and stone masonry substrates were modeled. The models were validated against experimental data. Additional windows with aspect ratios of 1.5 and 2.0 were also modeled for investigation. The models were used to conduct a parametric investigation with the parameters consisting of substrate flexibility, anchor fixity conditions, window size and aspect ratio, frame rigidity, number and spacing of anchors, and the threat level as defined by reflected pressure-impulse combinations. The significance of each parameter is illustrated with emphasis placed on the magnitude of anchor shear and tension design forces. The distribution of anchor forces is obtained numerically. Anchor forces and distributions are compared with those observed experimentally. Design force distribution along the perimeter of window frames is recommended for use in design. The paper provides the results of numerical simulations illustrating the significance of design parameters on anchor design force levels and their distributions. [ABSTRACT FROM AUTHOR]

A comprehensive experimental investigation was conducted on blast-resistant window anchors involving 46 tests of double-pane insulated glass units (IGUs) anchored to structural steel, reinforced concrete, concrete block masonry, and stone masonry substrates. The tests were conducted using a shock tube. The windows were glazed with security films of different thickness. Different number and spacing of steel anchors were used to secure the window frames to substrates. Each window was subjected to two levels of blast loads, consisting of 28 kPa, 207 kPa-ms, and 69 kPa, 621 kPa-ms reflected pressure–impulse combinations. The windows were instrumented to measure anchor forces. The anchors developed out-of-plane shear forces and in-plane axial tension associated with postbreak membrane action. The results indicate that anchor shear forces show variations with window stiffness, substrate type, and anchor arrangements, often developing lower forces than those computed based on the static application of blast loads, indicating significant inertia resistance. Rigid substrates produce higher anchor forces. In addition to the experimental results, the paper presents single-degree-of-freedom analysis results for anchor force computation, indicating good correlations with experimental data. [ABSTRACT FROM AUTHOR]

In the past years, special attention has been drawn to the explosion and its effect on various structures, especially thin-walled structures. One of the most effective factors for changing the behavior of such structures is thermal and shock loads caused by explosions. In the meantime, considering the geometric nature of the shells, which have a wide surface and thinness, as well as their wide application in various industries such as missile industries, nuclear industries, shipbuilding and silo construction, it is necessary to investigate the effect of these loads on the nonlinear dynamic behavior of the shells. However, knowing the large deformation of such structures under these loads, practical and cost-effective solutions such as strengthening the shells using hardeners are recommended. On the other hand, implementation problems and the possibility of creating an opening in the shells lead to a change in their behavior. In this thesis, using the ABAQUS finite element software, the elastoplastic response of single-curvature steel shells with and without opening and stiffener against blast loads is investigated. For this purpose, the effect of the supporting conditions, the thickness of the single curved shell, the mass of the TNT material, the distance from the place of explosion to the centre of the shell, the curvature of the shell, and the effect of opening and stiffener have been investigated. The results indicated better performance of the shell with the bearing support condition compared to other support conditions. Increasing the curvature of the shell initially led to an increase in displacement and then a decreasing trend. Results of the research indicate that the creation of circular and square openings has reduced the stiffness of the shell, followed by an increase in displacement, and the increase in displacement for square openings is more than circular openings. [ABSTRACT FROM AUTHOR]

Considering the remarkable growth in research activities and publications on blast-proof materials and structures in recent years, this article is trying to identify and highlight topics related to blast-proof structures and review representative papers that are related to the topics. A study of the research done in the domain of blast-proof structure and materials with an emphasis on recent works. Due to the wide development in blast-proof structures in the last decades, it is reasonable to cut down the study to a limited area by focusing on the blast-proof plate issues only. The study is related to deformation-fracture behavior, blast-loading, materials selection, and fabrication techniques of blast-proof. This study is planned to present the readers with a big-picture of studies and applications related to blast-proof. An attempt has been made here, to contain all the main portions in the blast-proof. [ABSTRACT FROM AUTHOR]

Structures subjected to blast loads have been studied in the past decades to characterize their behavior. However, this type of analysis can be difficult, which normally occurs in structures subjected to high-impact dynamic loads. Based on this, software was developed to represent the behavior of thin plates subjected to explosive loads, in terms of displacement, strain, stress, and frequency content. Moreover, parametric analysis is also possible, considering variations in the mass of the explosive and its distance from the plate.

The spurt in terrorist activities worldwide has drawn the attention of engineers and researchers to the vulnerability of building structures to blast loads. Response of masonry-infilled reinforced concrete (RC) frames subjected to blast loads is a widely researched area that still poses considerable complexity and challenges. Most of the works are based on finite element (FE) methodology to simulate the blast-induced behavior of the masonry-infilled RC structures considering the material constitutive and interaction aspects. Many literature studies have focused on FE codes for numerical modeling of masonry-infilled RC frames and interpretation of their response to various blast load scenarios (far-field, near, and contact blasts). The review presented herein addresses the aspects to include: Estimation of the blast load parameters, including the code provision and its simulation in the analysis module; updated knowledge on geometric and material modeling; effect of strain rate on constitutive parameters while modeling the materials; macro, micro, and simplified micro approaches to model masonry infill walls and their response under blast loading; modeling of interaction between RC frame and masonry infills and the performance of the integral and nonintegral system under blast loading. It is envisaged that such studies, in turn, would facilitate evolving the rational design methodologies for the blast-resistant design of framed structures. At the end of this paper, some parametric studies of field interest that are carried out in the literature are reported to understand the behavior of masonry-infilled RC frames against blast loads and derived some valuable conclusions. The review presented in this study provides a thematic analysis of the available literature aimed to assist the analyst in selecting a suitable tool for investigating masonry-infilled RC frames exposed to blast loads. [ABSTRACT FROM AUTHOR]

High explosives are hazardous materials that are frequently used in industrial production which involves many safety and risk problems. To investigate the influence of the explosive charge shape on near-field blast loads (<1.0 m/kg1/3 in this study), 12 shots of field blast tests were carried out. The reflected overpressures of 1 kg TNT with different charge shapes at a distance of 800 mm and the incident overpressures at a distance of 1310 mm were measured and analyzed. The fireballs produced by the explosions were recorded by a high-speed camera and compared with each other. Results show that the fireball of a non-spatial symmetry explosive is non-uniformly distributed, which indicates the released energy is also non-uniform. The charge shape effect was further investigated using a verified numerical model. The experimental and numerical results show that the charge shape has a significant effect on the key parameters of blast loads such as the incident overpressure, the reflected overpressure, and the impulse. However, the influence of the charge shapes crumbled away with the increase of scaled distance. When the scaled distance is larger than 5.0 (6.0) m/kg1/3, the hemispherical (cylindrical) charge shape effect on the reflected peak overpressure and the impulse can be neglected. [ABSTRACT FROM AUTHOR]

Autoclaved aerated concrete (AAC) blocks have widespread popularity in the construction industry. In addition to lightness, these materials have other advantages, including fire resistance, low acoustic and thermal conductivity, ease of cutting and grooving, and simple transportation. Since the behavior of AAC under severe dynamic loading conditions such as blast loads has not been adequately studied in the literature, in the current paper, the behavior of masonry walls constructed with AAC blocks was evaluated under blast loading. In this study, after performing experimental testing on materials and obtaining their compressive, tensile, and shear strength values, the finite element (FE) models of AAC-based masonry walls were created in the ABAQUS/Explicit nonlinear platform. Three different wall thicknesses of 15, 20, and 25 cm were simulated, and the models were analyzed under a lateral explosion caused by 5 and 7 kg of TNT at the stand-off distances of 2, 5, and 10 m from the wall face. The stress distributions, displacement responses, adsorbed energy, and crack propagation pattern were investigated in each case. The results showed the inappropriate behavior of these materials against explosion loads, especially at shorter distances and on walls with less thickness. The outcome gives valuable information to prioritize these walls for possible blast strengthening. [ABSTRACT FROM AUTHOR]

This paper summarizes the findings of two full-scale blasts tests on a steel braced frame structure with composite floor slabs, which are representative of a typical office building. The aim of this research study was to experimentally characterize the behavior of conventionally designed steel braced frames to blast loads when enclosed with conventional and blast-resistant façade. The two tests involved a three-story, steel braced frame with concentrical steel braces, which are designed to resist typical gravity and wind loads without design provisions for blast or earthquake loads. During the first blast test, the structure was enclosed with a typical, non-blast-resistant, curtainwall façade, and the steel frame sustained minimal damage. For the second blast test, the structure was enclosed with a blast-resistant façade, which resulted in higher damage levels with some brace connections rupturing, but the building did not collapse. Observations from the test program indicate the appreciable reserved capacity of steel brace frame structures to resist blast loads.

Complex numerical simulations of tunnels are often used to model effects of high strain rate surface loads. Most of this modeling ignores soil's strength dependency on strain rate to lessen the complexity. A series of Split Hopkinson Pressure Bar (SHPB) tests emulates the high strain rate compression occurring in blast events, for Nile Silty Clay (NSC) samples. The Cowper Symonds parameters are calibrated to SHPB test results and are used in advanced three-dimensional finite element analysis of a benchmark tunnel problem using Abaqus/Explicit software. The shallow tunnel in NSC formation is subjected to a blast event at the ground surface simulated by the CONWEP algorithm. The Smoothed Particle Hydrodynamic (SPH) mesh-free technique captures the crater formed due to the explosion. Results from the benchmark problem show that including the strain rate dependency in the analysis leads to a significant reduction in the calculated tunnel liner straining actions and deformations.

The purpose of this study is to analyze numerically the effect of explosions on orthotropic slabs which have partial fixity placement and stiffeners in the x direction, namely in the short span direction. The modified blast load dynamic behavior is from Reed’s equation with 4th order polynomial on orthotropic plates with x-direction stiffener. The localized blast load centered in the middle of the strain, and the effects of thickness and stiffening on the vertical deflection of the plates are solved numerically using two auxiliary equations in the x and y-directions. It is found that there is vertical deflection with related to time.

• Development and validation of Finite Element model for a parametric study on the effect of Soil Structure Interaction on G + 11 Reinforced concrete frame subjected to Blast Loads. • Rigid base, Loose, Medium, and Dense soils are considered for studying the SSI effect on G+11 RC frame exposed to Blast Loads of 500 kg TNT, 1500 kg TNT and 2500 kg TNT charge weights at 10 m standoff distance. • Storey displacement, storey drift ratio, velocity, acceleration and base shear for structures with and without Soil Structure Interaction effect are studied. • For all surface blasts and soil base conditions considered, the ground floor is the most vulnerable to collapse. • Study recommends measures to mitigate damage due to surface blasts on multi-storey reinforced concrete structures. All Nuclear power plants consist of several structures of varying importance that have to be designed for dynamic loading like earthquakes and impacts that they might be exposed to. Research on the influence of dynamic loading from blast events is still crucial to address to guarantee the general safety and integrity of nuclear plants. Conventional structural design approaches typically ignore the Soil-Structure Interaction (SSI) effect. However, studies show that the SSI effect is significant in structures exposed to dynamic loads such as wind and seismic loads. The present study is focused on evaluating the Soil-Structure Interaction effects on G + 11 storied reinforced concrete framed structure exposed to unconfined surface blast loads. The SSI effect for three flexible soil bases (i.e., Loose, Medium, and Dense) is evaluated by performing a Fast Non-linear (Time History) Analysis on a Two-Dimensional Finite Element Model developed in (Extended Three-Dimensional Analysis of Building System) ETABS software. Unconfined surface blast load of three different charge weights (i.e., 500 kg TNT, 1500 kg TNT, and 2500 kg TNT) at a standoff distance of 10 m are applied on the structure. Blast wave parameters are evaluated based on technical manual TM-5–1300. The blast response of the structure with and without the SSI effect is studied. It is concluded from this study that, there is a significant variation in dynamic response parameters of the structure with flexible soil bases compared to rigid or fixed base. For all magnitudes of surface blasts and soil base conditions, the ground floor is the most vulnerable floor against collapse. The study recommends measures to mitigate the damage due to unconfined surface blasts on multi-storey reinforced concrete structures. [ABSTRACT FROM AUTHOR]

Cellular concrete is a building material with highly porous structure in the matrix. Due to its excellent thermal and sound insulation performance, low-density cellular concrete (≤600 kg/m3) is often used in the construction of non-structural elements in residential and industrial buildings. During service, low-density cellular concrete elements may be subjected to blast loads induced by chemical or gas explosions. Therefore, a material model that can accurately describe the mechanical behavior of low-density cellular concrete is essential to investigate the damage and dynamic response of cellular concrete elements subjected to blast loading. Previous study indicated that low-density cellular concrete exhibits a cap-shaped compressive meridian. However, the commonly used brittle material models adopt the basis of a monotonical increase in the deviatoric strength with increasing hydrostatic pressure, which is contradictory to the experimental observations of low-density cellular concrete. Therefore, this study aims at developing a material model for predicting the dynamic response of low-density cellular concrete elements subjected to blast loads. Firstly, a series of laboratory tests were conducted to study the mechanical properties of low-density cellular concrete. The quasi-static, triaxial and dynamic properties, including the damage evolution modes, the compressive meridian, the hydrostatic pressure-volumetric strain relationship, and the strain rate effects were identified. Secondly, a plastic-damage material model of low-density cellular concrete was proposed and the material parameters were calibrated by the laboratory test results. To verify the feasibility of the model, single element simulations were carried out and results indicated that the model can accurately describe the complex behavior of low-density cellular concrete. Thirdly, numerical simulations were conducted to validate the proposed model by comparing predictions with blast test results from the literature. The numerical model accurately predicted the displacement responses and failure processes of low-density cellular concrete elements, with a maximum difference of 21 mm for maximum displacement and only 2 mm for residual displacement. The results demonstrate the high accuracy of the developed model in predicting the dynamic response and damage of low-density cellular concrete elements under various blast loading scenarios. • Low-density cellular concrete exhibits shear-compaction with confinement. • A decrease in deviatoric strength with the hydrostatic pressure was observed due to the collapse of pore structures. • A plastic-damage material model of low-density cellular concrete was proposed. • The model has high accuracy in simulation of low-density cellular concrete elements under various explosion scenarios. [ABSTRACT FROM AUTHOR]

This work aims at investigating the nonlinear transient response of fluid-conveying pipes made of graphene nanoplatelet (GPL)-reinforced composite (GPLRC) under blast loads and in a thermal environment. A modified Halpin–Tsai model is used to approximate the effective Young's modulus of the GPLRC pipes conveying fluid; the mass density and Poisson's ratio are determined by using the Voigt model. A slender Euler–Bernoulli beam is considered for modeling the pipes conveying fluid. The vibration control equation of the GPLRC pipes conveying fluid under blast loads is obtained by using Hamilton's principle. A set of second-order ordinary differential equations are obtained by using the second-order Galerkin discrete method and are solved by using the adaptive Runge–Kutta method. Numerical experiments show that GPL distribution and temperature; GPL weight fraction; pipe length-to-thickness ratio; flow velocity; and blast load parameters have important effects on the nonlinear transient response of the GPLRC pipes conveying fluid. The numerical results also show that due to the fluid–structure interaction, the vibration amplitudes of the GPLRC pipes conveying fluid decay after the impact of blast loads. [ABSTRACT FROM AUTHOR]

A pressure-impulse (P-I) diagram provides a quick tool to assess the resistance of a structural system to blast loads, based on a nonlinear single-degree-of-freedom (SDOF) analysis. Thus, instead of performing many SDOF analyses, the P-I diagram is the limit curve representing the combination of pressure and impulse for which the designed damage of the structure is achieved (commonly defined by the allowed maximum displacement). In this paper, nonlinear SDOF equations are represented in a dimensionless form for linear-elastic, elastic-plastic, and elastic plastic with hardening systems. Dimensionless P-I diagrams are derived for triangular blast load, and they are represented by the dimensionless parameters of the problem. Based on regression analysis, simplified empirical equations are developed to quickly calculate the dimensionless and absolute P-I diagram for a given case without performing any additional structural or numerical analysis. The accuracy of the suggested method is proved by statistical parameters and by a case study showing its capabilities. The study is limited to a solution of a classical SDOF system but may be extended to a more realistic scenario in which an equivalent SDOF equation is commonly adopted. [ABSTRACT FROM AUTHOR]

Corrugated steel-concrete-steel (CSCS) panels have considerable potential for resisting blast loads. They replace flat steel plates of steel-concrete-steel (SCS) panels with corrugated steel plates on the protected side. In this study, a finite-element model (FEM) of the CSCS panel was developed using LS-DYNA version R8 and validated by the blast tests reported in the literature. The calculated results indicated that the dynamic response of the CSCS panel was significantly different from that of the SCS panel as well as the damage modes of the panels. Three failure modes were observed in the CSCS panels subjected to blast loads. The influences of the structural parameters such as the flute spacing, flute angle, thickness of the corrugated steel plate, steel strength, and bonding strength were determined based on the developed FEM. It was found that the flute spacing had a minor effect on the damage to CSCS panels exposed to blast loads. In contrast, the blast-resistance performance of the panels significantly improved by increasing the flute angle, thickness, and strength of steel. The flute angle of the corrugated steel panel had the most significant contribution to the blast resistance of CSCS panels. The use of high-strength steel is not recommended for fabricating the CSCS panels. Also, the bonding strength remarkably influenced the damage and the energy absorption mechanism of the CSCS panels. [ABSTRACT FROM AUTHOR]

This paper presents the issue of determining the blast load on an engineering structure. In cases of industrial accidents or terrorist attacks, in many cases it is necessary to determine the necessary explosion parameters to determine the response of the structure, preferably in a simple and time-saving manner. In such a way, the empirical relationships can be used to estimate the selected parameters of the explosion load. Many empirical relationships have been derived in the past, but not all are suitable for different types of explosions. This article compares and validates experimentally determined selected explosion parameters for the chosen explosive with empirical relationships. For comparison, three already verified and frequently used calculation procedures (Kingery, Kinney, Henrych) and one newly derived procedure (PECH) were used. As part of the experimental measurements, blast wave explosion parameters for small charges were determined for near-field explosions. The general-purpose plastic explosive Semtex 10-SE was used for the experiments. The results of the comparative study presented in this article demonstrate the importance of taking these procedures into account for a reliable determination of the effects of blast actions on buildings. [ABSTRACT FROM AUTHOR]

This study presents a simplified blast load prediction method on structures behind a protective barrier. The proposed method is basically an empirical approach based on Kingery-Bulamsh (K-B) chart and finite element (FE) analysis results. To this end, this study divides the structure into three regions by three critical points. Blast loads at each critical point can be calculated based on K-B chart and an approximation according to FE analysis results. Finally, peak reflected overpressure and impulse distributed on the structure can be approximately estimated by linearly connecting blast loads at each critical point. In order to confirm a feasibility of the proposed method, a series of numerical simulations were carried out. The simulation results were compared with FE analysis results which are presented in the open literature. From such comparisons, it was found that the proposed method is applicable to predict blast loads on structures behind a protective barrier.

To obtain the failure mode and damage mechanism of a RC box girder under internal blast loads, the dynamic response process of the RC box girder under internal blast loads was carried out in an experiment and numerical simulation. The results show that after the blast, the failure morphology of the numerical simulation was in good agreement with that of the experiment. The front-face surface of the top slab was damaged by a compressive wave, and the back-face surface was damaged by a tensile wave. There were obvious transverse cracks at the joint between the web and the top slab (bottom slab), and there were many vertical cracks in the web. A large area of penetrating damage occurred in the center of the bottom slab. [ABSTRACT FROM AUTHOR]

Protective compartments are typically used to protect some specific structures from internal explosions, such as industrial buildings that contain devices that may explode in certain circumstances. This research investigates how the response of reinforced concrete (RC) compartment structures subjected to internal blast loads are affected by the following aspects: introduction of material nonlinearity in the analysis, reinforcement ratio, and aspect ratio of the compartment. To achieve this goal, a calibrated and sophisticated FE numerical model is introduced, and a parametric study for the intended aspects is carried out. A discussion of the results and conclusions are offered, which show the role of each aspect in the dynamic performance of the compartment structures. The main conclusions are as follows: introduction of material nonlinearity in this type of analysis and for these structures is very important and significant in obtaining accurate outputs that are similar to actual behavior; the reinforcement ratio has a significant effect on the response and its effect varies depending on the thickness of the compartment; in general, increasing the reinforcement ratio enhances the behavior and reduces the stresses in the compartment; and the aspect ratio of the compartment does not show a clear pattern on the response of such structures under internal blast loads. [ABSTRACT FROM AUTHOR]