Blast Loading Scenarios Research Articles

Failure analysis and structural resilience of a masonry arch Bridge subjected to blast loads: The Case study, Halilviran Bridge

This 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.

A macro-scale constitutive model of low-density cellular concrete for blast simulation

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.

Assessment of a Simplified Methodology for Preliminary Blast-Resistant Design of Insulated Precast Concrete Wall Panels

Abstract A Blast loading history can be represented by the peak pressure value and the impulse. Combinations of pressure and impulse of various blast loading scenarios can be collected to draw a pressure-impulse (P-I) curve that corresponds to a level of damage of a blast-resistant structural component. The P-I curve is typically used for a preliminary design or assessment of blast resistance structural components. Generating a P I curve for a given structural component and level of protection requires repeatedly ru nning a single degree of freedom system (SDOF) model, which can be tedious for early design stages. Hence, a simplified approach (i.e., the normalization approach) was utilized to promptly generate the P- I curve for insulated precast concrete wall panels, which relies on shifting a control P I curve using normalization factors. The generated P-I curves using the normalization approach are validated with the traditional SDOF approach curves; 95% of the examined insulted panel configurations have an error between +/-7%. As a result of the reached low error percentages, a spreadsheet- design tool was developed using this approach. The tool can further enable rapid evaluation of the performance of insulated precast concrete panels under blast loading during the preliminary design phase.

Performance of reinforced concrete slabs subjected to simultaneous fire and blast loads

Reinforced concrete (RC) slabs might experience severe damage from multiple hazards such as fire, explosion, and impact during their service life. RC slabs under independent or sequential hazard such as fire or blast loading have been intensively investigated. In reality, fire and explosion often occur simultaneously instead of occurring one after the other as assumed in some previous studies. Simultaneous actions of thermal loading and blast loading on structures are likely to generate different responses or even different response modes and failure mechanisms of structures as compared to independent or sequential actions of the two loads on structures. However, very limited study has been conducted to investigate the performance of RC slabs under simultaneous fire and blast loads. This study investigates the dynamic performance of RC slabs subjected to concurrent fire and blast loads, considering the simultaneous actions of thermal-induced stress, deformation, material deterioration and blast loading. The numerical model is first calibrated with the test results of RC slab under fire or blast loading. With the calibrated numerical model, the effect of thermal stress induced by fire loading on the blast performance is investigated. The influences of fire duration before the occurrence of explosion, as well as the blast loading scenarios and RC slab parameters on the structural responses are investigated. The dynamic responses induced by blast loading after the fire action as usually assumed in the literature are also calculated and compared with those obtained from simultaneous fire and blast loads. Their implications on representing the effects of coupled concurrent fire and blast loads on structural performances are discussed.

Finite Element Analysis-Based Blast Performance Evaluation for Reinforced Concrete Columns with Shear and Flexure Failure Modes

Blast loads have significantly damaged non-ductile reinforced concrete building structures with seismically deficient column details, which have lower shear capacity than the building structures with the current code-required details. This paper aims to evaluate the blast performance of non-ductile (shear-governed) and ductile (flexure-governed) RC columns using ductility- and residual capacity-based performance limits. To accomplish this research goal, the shear- and flexure-governed RC column models were developed using a finite element method and validated with previous experimental results. The efficient blast modeling method representing the reflected and incident waves was implemented in the validated column models, and these were simulated under various blast loading scenarios. The blast-induced responses for each column were investigated and utilized to determine the performance levels using the two different performance limits. The flexure-governed column model has higher performance levels than the shear-governed column model because of the lower ductility capacity of the shear-governed column model. The residual capacity-based performance level of the shear-governed column was underestimated compared to the ductility-based limits specified in a current design code.

Comparison of risk-based robustness indices in progressive collapse analysis of building structures

A current challenge in Structural Engineering is the identification of a robustness index for the design of structures subject to low-probability high-consequence load events. Robustness indices proposed in the literature have not been subject to comprehensive scrutiny. Few comparisons presented so far have been limited to simple academic examples involving idealized systems, which cannot suggest robustness values for practical design. In this paper a comprehensive evaluation of two risk-based robustness indices is presented, addressing progressive collapse of regular frame structures subject to damage by abnormal loads. Herein frames of different aspect ratios are considered, subject to local damage of different size, in hazard-independent and hazard-dependent (blast loading) scenarios. System damage states include plastic bending failure of beams, as well as local and global column crushing. Moreover, robustness indices are compared for structures conventionally designed, for structures strengthened following the codified Alternate Path Method (APM), and for structures resulting from risk-based optimization, for different hazard probability levels. Results suggest that the robustness index of Baker, Schubert and Faber performs better when comparing conventional to APM-strengthened codified designs. The Praxedes, Yuan and He robustness index is less sensitive but appears to be more appropriate to describe structures resulting from risk-based optimization.

Deep learning-based analysis to identify fluid-structure interaction effects during the response of blast-loaded plates

Blast events within urban areas in recent decades necessitate that protective design is no longer reserved for military installations. Modern civil infrastructure composed of light-weight, flexible materials has introduced the consideration of fluid-structure interaction (FSI) effects in blast-resistant design. While the action of blast loading on massive, rigid structures in military fortifications is well established, assessment of FSI effects is, at present, only possible through computationally expensive coupled simulations. In this study, a data-driven approach is proposed to assist in the identification of the blast-loading scenarios for which FSI effects play a significant role. A series of feed-forward deep neural networks (DNNs) were designed to learn weighted associations between characteristics of uncoupled simulations and a correction factor determined by the out-of-plane displacement arising from FSI effects in corresponding coupled simulations. The DNNs were trained, validated and tested on simulation results of various blast-loading conditions and material parameters for metallic target plates. DNNs exposed to mass-per-unit-area, identified as an influential factor in quantifying FSI effects, generalised well across a range of unseen data. The explainability approach was used to highlight the driving parameters of FSI effect predictions which further evidenced the findings. The ability to provide quick assessments of FSI influence may serve to identify opportunities to exploit FSI effects for improved structural integrity of light-weight protective structures where the use of uncoupled numerical models is currently limited.

Performance of foam-filled kirigami corrugated sandwich panels as sacrificial cladding against blast loads

In this study, the blast mitigation performance of kirigami corrugated (KC) panels filled with polyurethane foam as sacrificial cladding was investigated. Firstly, the effect of filling polyurethane (PU) foam on the energy absorption capacity and deformation mode of KC units was investigated by quasi-static compression. Numerical model was then built and validated. Following this, blast simulations were conducted to investigate the protective effectiveness of the aluminum foam panel, KC panel, and foam-filled KC panel as cladding for comparison. The blast loading effects on the structure without protection were also calculated and compared with different types of cladding. The key evaluating parameters, including peak transmitted load to the protected structure, energy absorption, and the crushed depth of the front plate, were used to evaluate the mitigation performance under various blast loads. The numerical results demonstrated the superior mitigating performance of foam-filled KC sandwich structures under various blast loading scenarios. The proposed foam-filled KC panel shows a higher energy absorption capacity than aluminum foam panels. The foam-filled KC panels with various densities of PU foam under different blast loads were also conducted to investigate its influence on blast mitigation performance. It was found that the second peak in the transmitted load can be reduced for KC panels with a higher density of the foam, as it leads to higher energy absorption capacity and later densification of the core against blast loads.

Experimental Validation and Numerical Analysis of a High-Performance Blast Energy-Absorbing System for Building Structures

The paper presents a full-scale blast testing experimental campaign conducted on an energyabsorbing connector comprising thin-walled inversion tubes as kernel elements mounted in a façade protective panel. LS-DYNA finite element predictions of the global and local deformation/inversion of the panel/connectors compared reasonably well with the experimental observations. After validation, the numerical model was used to analyze the response of a simple idealized reinforced concrete structure under three blast-loading scenarios: the first two scenarios produce, approximately, the same impulse but are significantly different in terms of load duration and overpressures, and represent a far-field and a near-field scenario (1600 kg TNT at 20 m (i) and 150 kg TNT at 5 m (ii), respectively); the third scenario is more demanding, and consists in a half standoff distance of the second (150 kg TNT at 2.5 m (iii)). These numerical simulations allow to assess the effect of standoff distance and blast loading on the effectiveness of the protective system. One may conclude that the introduction of EACs strongly limits the forces imparted to the protected structure, reducing significantly the corresponding energy absorption demand. Comparing the energy absorbed by the structure in different scenarios, with and without the protective system (8 × ϕ64 × 2 mm), one can see that these reductions can reach, respectively 67%, 72% and 68% in the far-field, near-field and very near-field explosions.

Simulating air blast on concrete structures using the volumetric penalty coupling of isogeometric analysis and peridynamics

A stabilized Isogeometric formulation of compressible flows is coupled to a large-deformation inelastic solid with an M7 Microplane constitutive model of concrete failure discretized in the framework of correspondence-based Peridynamics with bond-associated stabilization. The fluid–structure interaction (FSI) coupling makes use of a simple volumetric penalty technique that enables effective handling of the solid fracture and fragmentation. The capabilities of the FSI framework presented are demonstrated, in 3D, for point-charge detonation on concrete slabs. Slabs of varying thicknesses are simulated to capture the typical behavior of concrete under blast loading scenarios.

Dual-mechanism auxetic-core protective sandwich structure under blast loading

This paper introduces a protective sandwich structure with simultaneous auxetic compression and tension behaviour (termed as the dual-mechanism) in the core. To achieve the proposed mechanism, a novel architected cellular structure, named as the dual-mechanism auxetic (DMA), was developed. The protective performance of the DMA was examined by subjecting the DMA-core sandwich panel (DMASP) to blast loading through computational modelling. A series of dynamic numerical models were developed in LS-DYNA, and validated with the past experimental results. The protective performance of the DMASP was evaluated comprehensively based on energy absorption, stress mitigation, and deflection control. Moreover, the protective performance of the DMASP was compared with an equivalent areal density solid plate. In addition, parametric studies were conducted to investigate effects of various design parameters and explosive environments on the protective efficacy of the DMASP. The numerical simulations uncovered that, in addition to high energy absorption capacity of the DMA core, the dual-mechanism was beneficial to mitigate high stress transfer to the protected structure by redirecting stress in the lateral direction through auxetic tensile behaviour. Furthermore, the DMASP offered better protective performance than the equivalent solid structure with respect to all the evaluation criteria under different blast loading scenarios.

Predicting the failure mechanism of RC slabs under combined blast and impact loading

The dynamic structural behaviour and failure mechanisms of the reinforced concrete (RC) slabs under the combined blast and impact loading is numerically evaluated using the software LS-DYNA. The developed material model for concrete includes the plasticity behaviour under dynamic loading. The developed model includes the modified equation of state (EOS) which accounts for the loss of cohesive property and increase in compaction strength of the concrete material. The failure surface includes the effect of strain rate along with the lode angle and damage variable. The behaviour of concrete at low and high hydrostatic pressure is predicted with the developed model. The model has been formulated using a user-defined material model (UMAT). The predictions of the developed UMAT and in-built Winfrith concrete model (WCM) is compared with experimental results available in the literature. The developed concrete model can predict the failure mechanisms and the dynamic response of the slab accurately when compared with the results of WCM. Only limited experiments are available on the behaviour of RC slabs under combined blast and impact loading. Hence, the validation for analysis of the impact and blast loading scenario is carried out separately with the experimental results. The performance under the combined loading scenario is analysed by varying the sequence of applying the impact and blast loads. The slab subjected to impact-blast loading showed an increased dynamic response. The slab shows severe spallation, scabbing because of the flexural shear mode of failure caused by impact loading before the initiation of subsequent blast loading. The RC slabs subjected to longer impact duration before the initiation of subsequent blast loading under impact-blast loading scenario exhibited a more dynamic response. The failure of RC slabs under combined blast and impact loads shows increased localized damage and the stress concentration at the support caused by impact mass. The effect of slab thickness and reinforcement percentage is also studied by varying the velocity of the impact mass. The statistical analysis is carried out to study the uncertainty in the stress response of the developed model using the random variation of the input material parameters. The analysis is carried out to find the most influential input material parameter and the parametric study considered to study the combined impact and blast loading response of the slab.

Response Behavior of Buildings under the Simultaneous Actions of Surface Blast and Progressive Collapse

Due to the near blast condition, columns on the front face of the building may snap off in the blast load’s initial state, leading to a condition of the blast load and progressive collapse effects occurring simultaneously. Herein, the damages caused in the building produced due to progressive collapse under blast loading scenario are investigated. A nonlinear time history analysis of the three-dimensional (3D) model of a six-story building is performed for the progressive collapse following General Services Administration (GSA) guidelines. The surface blast effect is included using simulated air pressure and ground motion produced due to the blast. The progressive collapse analysis is performed for two cases, namely, (1) considering blast effect due to surface blast; and (2) neglecting the effects of the blast wave, and the results of the two cases are compared. The study results show that the effect of the duration of the transient loading used for the progressive collapse analysis has a significant influence on the response quantities of interest. Further, all response quantities of interest are considerably increased when the blast effect is considered compared to the case when the same is neglected.

Characterisation and validation of the JWL equation of state parameters for PE4

This investigation focused on determining the Jones-Wilkins-Lee (JWL) equation of state (EoS) parameters for the Australian made explosive PE4-MC. Four cylinder expansion (CYLEX) experiments were conducted using the T-20 methodology with measurements of the time of arrival of the copper cylinder on the perspex plate made using optical fibres connected to an optical pulse timer. Three different model parameter fits were then generated from the CYLEX test data. These were based on; (1) Traditional least-squares fit of CYLEX data to JWL EoS and (2) Inverse modeling method using LS-DYNA and LS-OPT (two different fits). The three parameter sets were then compared in terms of the accuracy of their predictions against two sets of blast loading experiments. The first set of blast loading experiments evaluated the different parameter fits at a scaled distance (Z) of 1.77–2.55 m/kg1/3, representing a mid-field blast loading scenario while the second set of blast loading experiments represented a near-field blast loading scenario (Z = 0.08–0.1 m/kg1/3). The JWL EoS parameters which were derived using the standard fitting method from the CYLEX test data (CYLEX) were shown to provide accurate predictions (within 5% of experiments) in the near-field but under-predicted the peak reflected pressure in the mid-field by more than 20%. The best predictions across both the near and mid-field blast loading scenarios was provided by the two parameters sets (LS-OPT Final and LS-OPT Select), which were derived using an inverse modeling approach, with the LS-OPT Select set of parameters being the preferred option. Additionally, comparisons between the experimental data and predictions using the JWL EoS parameters for the US made C4 explosive indicated that the blast loading in the mid-field was similar between C4 and PE4-MC, which was consistent with the previous literature. However, in the near-field C4 was predicted to provide higher blast loadings. This highlights the importance of validating an explosives EoS across a range of different scaled distances.

Dynamic bearing capacity of point fixed corrugated metal profile sheets subjected to blast loading

Blast loading scenarios and the corresponding hazards have to be evaluated for infrastructure elements and buildings especially at industrial sites for safety and security issues. Point fixed corrugated metal sheets are often applied as façade elements and can become a hazard for humans if they are pulled off. This paper investigates the dynamic bearing capacity of such structural members in terms of their general bending behavior in the middle of the span and pull-out behaviors at the fixing points. The elements are fixed at two sides and the load transfer is uniaxial. An experimental series with static and dynamic tests forms the basis to identify the predominant failure modes and to quantify the maximum stress values that can be absorbed until the investigated structural members fail. The experimental findings are applied to create and to optimize an engineering model for the fast and effective assessment of the structural response. The aim is the derivation of a validated model which is capable to predict the blast loading behavior of metal sheets including arbitrary dimensions, material properties, and screw connections. Results of this study can be integrated into a systematic risk and resilience management process to assess expected damage effects and the evaluation of robustness.

Pelvic Response of a Total Human Body Finite Element Model During Simulated Injurious Under Body Blast Impacts

Abstract Military operations in Iraq and Afghanistan have resulted in the increased exposure of military personnel to explosive threats. Combat-related pelvic fractures are a relatively new battlefield injury that poses a serious threat to military personnel. Injury prediction for these events continues to be a challenge due to the limited availability of blast-specific test studies and the use of established automotive-based injury criteria that do not directly translate to combat-related exposures. The objective of this study is to evaluate the pelvic response of the global human body models consortium (GHBMC) 50th percentile detailed male model (v4.3) in under body blast (UBB) loading scenarios. Nine simulations were conducted with mild or enhanced threat levels, and nominal or obtuse occupant positions. Cross-sectional force outputs from the superior pubic ramus (SPR), ilium, and sacroiliac (SI) regions were evaluated using previously developed injury risk curves (IRC). Additionally, maximum principal strain (MPS) data were extracted from the pelvic cortical bone elements. Results showed that shear force was the best predictor of fracture for the ischial and SI regions, while axial force was the best predictor for the SPR region. These outcomes were consistent with the load path of the simulated UBB events. The obtuse posture had higher peak force values for injurious and noninjurious outcomes for the SPR and SI region. The nominal posture had higher peak force values for noninjurious outcomes in the ischial region. These outcomes were supported by the MPS response present in these postures.

Numerical damage evaluation of perforated steel columns subjected to blast loading

The structural performance of perforated steel columns (PSCs) is significantly more complex than the one of solid web I-shaped elements under the diversity of blast loading scenarios. The damage criterion of PSCs is not only related to initial deformation response during the blast but also the residual axial load capacity and it can be considered as a reliable index after the blast effects. Therefore, the PSCs damages will be studied in two stages; direct and post blast effects. In the present study, the dynamic response of PSCs was numerically evaluated under different levels of blast threats using LS-DYNA software. Extensive explicit finite element (FE) analyses are carried out to investigate the effect of various parameters, such as web opening shapes, boundary conditions and strengthening details on the damage index and toughness of the PSCs compared to the parent steel sections. The results of the comparative study show that the damage and toughness decrease when the support condition changes from pinned to fixed ends through the two stages of loadings. PSCs give high toughness compared to its parent sections during blast shock stage while, a remarkable decrease in toughness is observed during the application of axial gravity after blast shock. Furthermore, the web opening shapes have slight effects on the global dynamic behavior of PSCs, particularly in terms of residual capacity. On the contrary, the retrofitting strategy using both closed holes at end and vertical stiffeners have an effective enhancement to get higher toughness in case of the extreme blasts.

Probabilistic framework for failure investigation of reinforced concrete wall panel under dynamic blast loads

Over the last decade, excessive devastations caused by extreme events, such as blast loading have raised significant concern on the performance of civil structural systems. Despite realizing the importance of inherent risk associated with this phenomenon, most of the studies neglected the effects of uncertainties associated with the system, wherein the design approaches have been entirely on deterministic scale. Hence, it is deemed important to identify the complexities in the system, and in this regard, a probabilistic framework is proposed which utilizes the effects of uncertainties in the system to compute the failure probabilities of a reinforced concrete (RC) structural member under extreme blast loading. The structural member adopted here is a three-dimensional (3-D) RC wall panel, which is modeled considering material and geometric nonlinearity, and the subsequent analysis is carried out under surface-burst and free airburst scenarios. High strain rate effect induced in the RC wall is modeled using available standard dynamic increase factors (DIFs) for concrete and steel. Uncertainty in the system is assumed in material capacity (strength), mechanical loads, and dynamic blast loads considering a certain mean and standard deviation. Responses are obtained in terms of deflection, stresses, and strains at center of the wall. Limit state of failure and the respective threshold limiting values are obtained from the United States Department of Defense manual, PDC-TR 06-08 (2008). Finally, first-order sensitivity analysis is conducted to show the extent of uncertainties in input parameters affecting the output response quantities. It is concluded that the uncertainty induced in the system has significant influence in the response of the wall panels under blast loading scenarios. Moreover, based on the sensitivity analysis performed, charge weight, standoff distance, and strength of concrete material are suggested to be crucial parameters for design of blast-resistant structures. To conclude, based on the currently considered scenario of intensity of blast, exposure type, and performance level required by the user, it is recommended to use wall panels of sizes more than 100 mm in civil structures, especially 125 mm to counter the effects of extreme blast loadings.

Dynamic response of dry cask storage systems for spent nuclear fuel to near field blast loading

Dry storage casks are the most common form of spent nuclear fuel (SNF) storage in the United States. An explosion near a spent nuclear storage facility poses a serious public risk due to the potential of radioactive leakage. In this study, for the first time, the structural performance of vertical steel–concrete-steel sandwich (SCSS) and reinforced concrete (RC) casks under blast loading scenarios is studied using explicit finite element simulations considering material and geometric nonlinearity and strain rate effects. The response of the cask is investigated in terms of stress levels, deformations, and peak accelerations. The conventional weapons (CONWEP) model was used to induce a blast load on the structure at varying blast charges. The accelerations experienced by the canister and the fuel assemblies, which are critical for design are estimated. The inherent vibration damping characteristics of the cask are evaluated, and a novel damper configuration is proposed to improve the energy dissipation capacity of the system. The results showed that the general integrity of the cask could be preserved in the presence of a thick reinforced concrete layer. However, due to the lack of a damping mechanism, the blast wave can propagate through the system and result in very large accelerations in the canister and the fuel assemblies. Results also revealed that the SCSS configuration has a more ductile response compared to the RC design. The results of this study could be used for the safety evaluation and design optimization of current casks in service and other cylindrical composite containment structures.

Numerical analysis of axial load effects on RC bridge columns under blast loading

Blast load and its effects on transportation infrastructure especially bridge structures have received considerable attention in recent years. The RC bridge columns are considered as the most critical structural members because their failure leads to collapse of the bridge. Although RC bridge columns are typical axial load-carrying components, the studies on blast-resistant capacity of RC bridge columns usually neglect the axial load effect since it is commonly assumed that neglecting the axial load leads to conservative predictions of column responses. This assumption is true when column failure is governed by flexural response since axial compressive load generates a prestress in column which compensates concrete tensile stress induced by bending response. When subjected to blast loads, column response however could be governed by shear response. In this case neglecting axial loading effect does not necessarily lead to conservative predictions of column responses. In this study, high-fidelity finite element (FE) models for both non-contact explosion and contact explosion were developed in LS-DYNA. The FE models were validated with field blast test data. Subsequently, intensive simulations of the RC bridge columns with and without axial load subjected to a wider range of blast loading scenarios, including far-field, near-field and contact explosion were conducted. The influence of axial load on the dynamic performance of RC bridge columns corresponding to different blast loading scenarios was discussed.