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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.

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 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]

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.

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.

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]

The effects of blast waves and their consequent damage to structures have been an increasingly popular research topic in the past decade. Various methods are used in blast load prediction on structures, including experimental, semi-empirical and numerical approaches. However, there is a demand for developing time-efficient predictive methods that help various professionals, such as engineering practitioners and first responders, in their regular activities. Machine learning (ML), as a subset of artificial intelligence (AI), has gained significant attention in various engineering applications over the past decades for its ability to aid decision-making. However, a critical gap exists in the comprehensive analysis of these ML models' transparency and interpretability levels. This paper presents a novel approach to employing explainable machine learning (XML) to predict the blast loads generated by high explosives. The primary objective is to assess the validity of utilising a machine learning (ML) framework for blast load predictions, examining the scientific consistency of the model's prediction process. This research utilises XML to interpret the ML model-based blast load prediction framework, marking the first documented use of XML in published literature for blast load prediction. This research study utilised three ML models, namely a) Decision Tree, b) Random Forest, and c) Extreme Gradient Boost (XGB) models, to predict blast loads on rigid structures. Validated numerical model results were used to generate the dataset to train the ML models, and the respective dataset consists of approximately 600 independent blast events. The models were evaluated for their predictability using error metrics: adjusted coefficient of determination (adjusted R2), root mean square error (RMSE), and mean absolute error (MAE). The overall ML model performance evaluation showed that the best-performing model, XGB, could make predictions with 98 % accuracy compared to validated numerical predictions. The XML explanations for the XGB models showcased that the blast load prediction procedure of the models aligns with the blast physics principles, ensuring the credibility of the developed ML models. In summary, these XML predictive models can be considered accurate and reliable for blast load prediction on structures. • Explainable machine learning models were used to predict blast loads on structures. • XGBoost model demonstrated remarkable accuracy in predicting blast loads. • Shapley Additive Explanations were used to explain the XGBoost model. • Model explanations adhere to fundamental blast theories. • Explainable machine learning was used for the first time in blast load prediction. [ABSTRACT FROM AUTHOR]

Portable explosions in the form of backpacks and suitcases have been at the forefront of various terrorist activities due to their ability to create unrest in crucial infrastructure such as railway stations. At close range, these portable explosives, with charge sizes ranging from 2 kg to 10 kg, can reasonably damage vital structural elements of a building. For example, the debris produced by breaching one slab can overload and damage the slabs below in a multi-storey structure or pile up to block the access and continuous functioning of a building during rescue operations. A "band-beam slab" or "slab with a shallow beam" is one of the most used slab types in modern multi-storey buildings, especially on basements and lower floors. The band-beam slabs are commonly used to save headspace and floor-to-floor heights of multi-storeyed buildings. Therefore, investigation of the performance of band-beam slabs under close-in detonation is an interest of crucial infrastructure projects. To this end, the work presented in this paper investigates the performance of band-beam slabs subjected to close-in detonations. Thirteen band-beam slabs were subjected to close-in detonations against Composition-4 (C4) charges of sizes varying from 2.5 kg to 4.5 kg. The panels were designed to withstand the overall blast load following the typical design guidelines. However, some variations were introduced in the design to observe the effect of (i) slab reinforcement ratio, (ii) primary longitudinal reinforcement ratio of the beam, (iii) shear link size and spacing in band-beams, and (iv) scaled stand-off distance. In general, all test specimens experienced minor to moderate damage. At the same time, it is observed that the effect of the shear reinforcement ratio and detailing of the reinforcement play a significant role in reducing the spalling and crater formation. The observations have been compared with the UFC-3–340-02 guidelines for spalling and breach and found that experimental results reasonably agree with UFC predictions. Finally, based on the observations, design recommendations in terms of additional reinforcement to control and mitigate spalling, cracking and scabbing were proposed. • Thirteen Band-Beam reinforced concrete slabs are studied for close-in detonations. • Spalling damage was observed for a majority of the panels due to close-in blast. • Additional reinforcement in the slab doesn't improve spalling damage in the panel. • Spall damage is effectively controlled by shear rebar spacing. • No breach observed for any tests including contact charge due to special C-hooks. [ABSTRACT FROM AUTHOR]

Blast loads may result Irretrievable damages in structures due to their high amount of applied energy to them during a short period of time. Strengthening and rehabilitation of the structures subject to these sort of loads would be a proper approach to mitigate these damages. Among the available approaches, use of composites so-called Fiber Reinforced Polymers (FRPs), because of their desire properties such as ease in installation and high strength to weight ratio, has been considered the most common solution in recent years. These composites, however, possesses some disadvantages such as low resistance against fire, low glass transition temperature, difficulties in application at low temperatures, impossibility of application on wet surfaces and lack of vapor permeability which have led to use innovative composite materials as alternative. These are normally made of cementitious matrix reinforced by continuous fibers (FRCM). These composites with cement based matrices have good mechanical performances, excellent resistance to high temperature and fire, and also good vapor permeability. Moreover, they can be applied on wet surfaces and in cases of low temperature. Therefore, FRCM materials may constitute an alternative to FRP materials for the strengthening of RC structures. In this paper, performance of RC columns which are subject to blast loading and strengthened with FRP and FRCM composites is investigated using Pressure-Impulse (P-I) diagrams. The results obtained in this study demonstrate that strengthening of structures by FRCM is more efficient in comparison to that of FRP in most cases of damages and therefore could be implemented to protect structures better against blast loads.

Increasing the number of explosive threats on the structures is a warning in the direction of safety. The design of structures against the blast loads in the past has been limited to military buildings and so on. Now, with the spread of science and threats against bridges, buildings and industrial structures will require a detailed examination of the performance of these structures against the blast load. In this study, the performance of structures against explosions, the damage to the structure and the important factors in the failure of the structure were investigated and the results show that the location of the structure of the explosive factor ratio has a significant effect on stability.

In this study, the Performance Based Design PBD method, which has been used only in seismic design by several codes, has been expanded to be applied to structures exposed to blast loads. The plastic hinge models used in PBD, which currently available for earthquake loads do not represent real behavior under the blast load. An analytical approach was proposed to represent the plastic behavior of flexural response under blast loads. The proposed model considers the following essential phenomena: concrete cover crushing, concrete core crushing, bar buckling in compression reinforcement, strain hardening in tensile reinforcement and softening in reinforcement bar. The proposed analytical approach has been validated with two experimental results of columns applied to blast loads and reasonable results has been seen.

Although many studies on the blast-resistant performance of structures have focused mainly on single members such as beams and columns, there is little research on the behavior of joints that are subjected to blast loads. In this study, the structural behavior of a slab–column connection subjected to blast load was investigated using a numerical analysis method. LS-DYNA was used as a finite element analysis program, and in order to improve the accuracy of numerical analysis, mesh size, material model, and simulation method of blast load were determined through preliminary analysis. The effect of different restraints of the joints, depending on the position of the columns in the slab, on the blast resistance performance was investigated. As a result, the highly confined slab-interior column connection showed better behavior than other edge and corner columns. The drop panel installed between the lower column and the slab was effective in improving the blast-resistance performance of the slab–column connection. For a more accurate evaluation of blast resistance performance, it was suggested that various evaluation factors such as ductility ratio, reinforcing stress, and concrete fracture area can be considered along with the support rotation, which is an important evaluation factor suggested by many standards. [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.

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.