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International Journal of Protective Structures
Journal Prestige (SJR): 0.841
Citation Impact (citeScore): 1
Number of Followers: 6  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2041-4196 - ISSN (Online) 2041-420X
Published by Sage Publications Homepage  [1176 journals]
  • Analysis of perforated corrugated steel columns subjected to bilateral
           cyclic loading

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      Authors: Ahmed Albarram, Qusay Al-Kaseasbeh
      Abstract: International Journal of Protective Structures, Ahead of Print.
      This research unveils numerical analysis of corrugated-shaped steel columns (CSCs) with perforations during seismic events. Using ABAQUS software, 34 tests were examined under constant and bilateral cyclic loads. Varying parameters involved numbers and levels of perforations, corrugation geometries, and steel thickness. Findings exhibited a favorable performance of CSCs with six corrugated geometries as compared with ones with four corrugated geometries. The enhancement in load capacities and ductility were reported at 25–32% and 40%, respectively. CSCs were seen most vulnerable to experience load capacity deterioration when perforations were located in the lower quarter zone of height. The maximum corresponding decline exceeded 30% among tests having all corrugated geometry faces perforated. Local buckling failure in the lower quarter zone was dominant in most cases with severe deformation observed by the presence of perforations in such zone. Increasing the steel thickness of CSCs improved load capacities satisfactorily and shifted the local buckling to outward buckling, and controlling the failure patterns. This research emphasizes the need for perforations in such innovative cross-section steel columns to play as service conducing area and cost-effective factor. The research also provides applicable solutions to optimize the structural behavior of CSCs and maintain safer design during seismic incidents.
      Citation: International Journal of Protective Structures
      PubDate: 2024-02-23T02:50:17Z
      DOI: 10.1177/20414196241235321
       
  • Vulnerability of reinforced concrete frames using anti-seismic hysteretic
           devices for the Lorca earthquake (2011)

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      Authors: David Dominguez Santos, Francisco Pallares Rubio, Pedro Muñoz
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Many buildings around the world are extremely vulnerable to serious and moderate earthquakes. Base isolation and energy dissipators are the traditional techniques in anti-seismic designs. The present paper focuses on the suitability of using hysteretic energy dissipators in braced buildings in low-to-medium seismic zones, such as southeast Spain. To this end, static (Push-over) and dynamic analyses have been carried out using the record of the Lorca earthquake (2011) in its most unfavorable direction (N-S), using reinforced concrete frames of low (5 stories frame), medium (10 stories frame), and high height (15 stories frame) with hysteretic dissipators (based on metal plasticization) and economical and easy-to-use devices. The results show that this type of solution is appropriate in the case described and indicate the advantages and disadvantages of its use in buildings in the study area. The results show that the effectiveness of the dissipative devices increases with the height of the frames, in terms of displacements, resistance, and distribution of moments in the primary structural elements of the frames (beams and columns).
      Citation: International Journal of Protective Structures
      PubDate: 2024-02-22T12:52:58Z
      DOI: 10.1177/20414196241233755
       
  • Explosive field trial for repetitive testing of VBIEDs to
           probabilistically measure blast and fragmentation hazards

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      Authors: Mark G Stewart, Michael D Netherton, Hao Qin, Jun Li
      Abstract: International Journal of Protective Structures, Ahead of Print.
      This paper describes results from an explosive field trial of the detonation of Vehicle-Borne Improvised Explosive Devices (VBIEDs). The purpose of the trials is to replicate tests with identical car type and explosive mass to help probabilistically characterise the uncertainty and variability of blast pressures and fragment hazards. These variabilities may be considerable, and it is important to recognise that the world is not deterministic. The paper describes the spatial variability (directionality) of incident pressure, impulse and time of positive phase duration, and compares these to results from a bare charge, and the hemispherical surface burst Kingery and Bulmash polynomials often used for predicting blast loads from IEDs, such as ConWep. This also allows directional airblast factors to be quantified. The spatial distribution of over 26,000 fragments on the ground is also presented over the 250 m × 300 m test arena. The fragment densities and velocities obtained from the witness panels are also described, and preliminary fatality risks were estimated. These data may help develop or validate airblast and fragment hazard numerical or other models. Ultimately, probabilistic approaches will provide decision support for the determination of safety distance and risk reduction measures to prevent fatality and injury from blast pressure and fragmentation hazards.
      Citation: International Journal of Protective Structures
      PubDate: 2024-02-14T03:08:57Z
      DOI: 10.1177/20414196241233757
       
  • Influence of fibre orientation parallel to impact direction on the impact
           response of unidirectional glass/epoxy composite: Experimental
           investigation on confinement and hybridisation

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      Authors: Bhaskar Ramagiri, Chandra Sekher Yerramalli, Nabodyuti Das
      Abstract: International Journal of Protective Structures, Ahead of Print.
      In a high-velocity impact phenomenon, the damage is localised, and for thick composite laminates, most of the projectile’s kinetic energy is absorbed through out-of-plane compression and shear mechanisms. In conventional composite laminate, as the fibre orientations are in the in-plane of laminate, the out-of-plane compression and out-of-plane shear of laminate are utilised. In composites, the out-of-plane compressive strength is significantly lower than the in-plane (fibre direction) strength. The present study investigates the impact response of unidirectional (UD) glass/epoxy composite targets with fibres oriented parallel to the impact direction. The lack of research on the impact behaviour of unidirectional glass/epoxy composites with fibre orientation parallel to the impact direction demands further experimentation and understanding of failure mechanisms. In this study, firstly, the impact response of UD glass/epoxy composites with fibres oriented parallel to the impact direction (GFID) was investigated and compared with conventional cross-ply (GFCP) and quasi-isotropic (GFQI) glass/epoxy laminates. Secondly, to address the issues of GFID splitting on impact, GFID was confined in both the hoop and normal-to-binder directions. Thirdly, the impact response of various hybrid GFID with and without confinement with GFCP as backing was evaluated. GFID under out-of-plane punch load fails by splitting, and its compressive participation depends on the impact velocity. GFID under the hoop and normal-to-binder direction confinement showed better specific impact energy absorption relative to pure GFID. The experimental results show that GFID wounds with carbon fibre used as a facing with GFCP as a backing provide better impact resistance at HVI conditions than conventional laminates of the same thickness. These findings suggest that the combination of GFID and GFCP targets can be used to have better impact resistance in various applications.
      Citation: International Journal of Protective Structures
      PubDate: 2024-02-10T09:55:38Z
      DOI: 10.1177/20414196241232676
       
  • Numerical modeling and simulation of cable barriers under vehicular
           impacts on a sloped median

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      Authors: Qian Wang, Emre Palta, Howie Fang
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Cable barriers are flexible barrier systems that are commonly used as median barriers in the United States for their general effectiveness and low installation and maintenance costs. The current cable median barrier (CMB) adopted by the North Carolina Department of Transportation was previously evaluated on flat terrain and found to satisfy the requirements of the National Cooperative Highway Research Program Report 350. Under in-service conditions (i.e., on a sloped median), the current CMB failed to stop small passenger cars in many incidents. The new roadside safety standard, Manual for Assessing Safety Hardware (MASH), recommends that CMBs be tested and/or evaluated on sloped medians. However, conducting full-scale crash tests on sloped median is extremely difficult and few experimental studies exist. In this study, finite element simulations were used to evaluate the performance of the current CMB design on a 6H:1V sloped median under MASH Test Level 3 conditions. To address the issue of vehicle underriding on the current CMB, two retrofit designs were developed and also evaluated on the sloped median. Two MASH compliant vehicles, a 1996 Dodge Neon and a 2006 Ford F250, were used to evaluate all three CMBs from both frontside and backside and with two initial impact points. The MASH exit-box criterion, MASH Evaluation criteria A, D, and F, vehicular responses, exit angles, and residual velocities were used to evaluate the CMB performance for structural adequacy, occupant risk, and post-impact trajectories. The simulation results showed that one of the retrofit designs could improve the CMB performance on a sloped median at MASH Test Level 3 conditions.
      Citation: International Journal of Protective Structures
      PubDate: 2024-01-08T07:53:31Z
      DOI: 10.1177/20414196241226725
       
  • Experimental study of the low-velocity impact behavior of open-cell
           aluminum foam made by the infiltration method

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      Authors: Mohsen Hajizadeh, Mojtaba Yazdani, Hosein Khodarahmi
      Abstract: International Journal of Protective Structures, Ahead of Print.
      This study examined the behavior and energy absorption of open-cell aluminum foam under different loading conditions. The foam was made by infiltration, a low-cost method that produced a uniform pore distribution. The foam was compressed using two machines with varying impact velocities and weights. The stress–strain and energy absorption curves of the foam were measured and analyzed. The results showed that the strain rate and the impact weight affected the compressive properties and energy absorption of the foam. The strain rate up to 264 s−1 with constant mass did not affect the plateau stress, which was the constant stress in the plastic region. However, at 264 s−1, increasing the impact weight increased the plateau stress and the energy absorption of the foam, which showed that the strain rate sensitivity depended on the impact inertia. The study revealed the dynamic characteristics of open-cell aluminum foam made by infiltration and provided insights for its use in impact protection. The study also showed that infiltration was a reliable and consistent method for making open-cell aluminum foam. The study highlighted the important roles of plateau stress and hardening effect in influencing the energy absorption of the foam under dynamic loading. The study suggested that future studies should consider the impact inertia as a parameter that affects the strain rate sensitivity of the foam.
      Citation: International Journal of Protective Structures
      PubDate: 2024-01-05T07:37:58Z
      DOI: 10.1177/20414196231225812
       
  • Wave-absorbing performance of alumina thin-walled hollow particles under
           freezing condition

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      Authors: Pengzhi Yan, Yu Wang, Pengxian Fan, Mingyang Wang
      Abstract: International Journal of Protective Structures, Ahead of Print.
      The reliability of the absorbing layer is crucial for realizing protective engineering’s protection function. However, the typical wave-absorbing material, sand, is unable to fulfill its intended wave-absorbing function in areas with seasonally frozen soil. This is because the internal pores of the material become filled with ice and the particles freeze. To address this issue, alumina thin-walled hollow particles were chosen as a new wave-absorbing material. These particles can introduce the gas phase into the absorbing layer which is essential for attenuating the stress waves and its wave-absorbing capacity under freezing conditions was investigated by the split Hopkinson bar (SHPB) test. According to the test data, the alumina thin-walled hollow particles are less dense than sand and have a lower wave impedance, allowing them to reflect more incident energy. Moreover, these particles have a better capacity for dissipating the absorbed energy, as compared to sand. Under freezing circumstances, the average transmittance coefficient of alumina thin-walled hollow particles is only 21.95% to 49.30% of ordinary sand. Additionally, the particle size positively correlates with the capacity for wave-absorption. The capacity of alumina thin-walled hollow particles to shatter and release the gas phase under impact stress significantly increases the compressibility of the absorbing layer under freezing conditions, which accounts for their enhanced wave-absorbing effectiveness. The stress-strain curve specifically manifests as a smoother curve and a longer stage of plastic energy dissipation. Other than that, the dynamic deformation modulus of the material and peak stress is lower, while the peak strain is larger. The findings of this study provide a low-cost, high-reliability solution to the problem of frost damage in the absorbing layer in regions with seasonal freezing.
      Citation: International Journal of Protective Structures
      PubDate: 2024-01-04T06:30:08Z
      DOI: 10.1177/20414196231226240
       
  • On the penetration of rigid spheres in metallic targets

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      Authors: Zvi Rosenberg, Yaniv Vayig
      Abstract: International Journal of Protective Structures, Ahead of Print.
      We present an empirical relation for the penetration depths of rigid spheres impacting metallic targets at ordnance velocities. This relation was derived through 2D numerical simulations for various sphere/target pairs, that followed their penetration depths in terms of the impact velocity, the sphere/target density ratio, and the dynamic strength of the target. The numerically derived empirical relation is shown to account for test data from several publications.
      Citation: International Journal of Protective Structures
      PubDate: 2024-01-03T12:21:56Z
      DOI: 10.1177/20414196231225813
       
  • High-velocity impact experiments and quantitative damage evaluation for
           finite ultra-high-performance concrete targets

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      Authors: Christoph Sauer, Jan Burtsche, Andreas Heine, Christoph Roller, Werner Riedel
      Abstract: International Journal of Protective Structures, Ahead of Print.
      In this work, we aim at improved characterization of target damage occurring as the result of projectile impact against ultra-high-performance concrete (UHPC). For this purpose, we present the results of high-velocity impact experiments with spherical steel projectiles and finite-thickness UHPC targets of approximately 115 MPa compressive cylinder strength in the impact velocity range from approximately 600 m/s to 1500 m/s. The data set obtained from these experiments includes residual projectile velocities as well as qualitative and quantitative information on damage. Quantitative damage information is mainly extracted from digital 3D post mortem targets, which are produced by 3D-scanning. For all damage quantities, a dependence on the impact velocity and the target thickness is discussed and used to provide possible explanations for the origin of the particular type of damage. The large data set presented in this work can constitute the basis for a comprehensive and quantitative verification and validation of analytical, empirical, and numerical models that describe the perforation of UHPC targets in the investigated impact velocity range.
      Citation: International Journal of Protective Structures
      PubDate: 2023-12-12T02:28:33Z
      DOI: 10.1177/20414196231216751
       
  • Dynamic performance of ultra-high performance fiber-reinforced concrete
           panel exposed to explosive loading

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      Authors: Masoud Abedini, Chunwei Zhang
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Ultra-high performance fiber reinforced concrete (UHPFRC) is a cement-based composite material mixing with reactive powder and steel fibers. It is characterized by its high strength, high ductility, and high toughness and such characteristics enable its great potential in protective engineering against severe dynamic loads. In the current research, the dynamic performance of the concrete panel made with ultra-high performance fiber subjected to explosive loading was investigated. For this purpose, several concrete panel samples were considered and modeled in ABAQUS finite element software. The accuracy of the numerical model is verified by comparing the numerical simulation results with available testing data. First, the considered panel was modeled with normal concrete then it was modeled with UHPFRC concrete, and the effect of using this type of concrete on the behavior of concrete panels was investigated. After analyzing and examining the models, their behavior such as the degree of vulnerability, more vulnerable points and changes in the locations that occurred in each of the models were obtained and compared. The results demonstrate that the use of UHPFRC significantly improves the blast performance of RC panels by reducing maximum and residual displacements, enhancing damage tolerance, and increasing energy absorption. The results also indicate that the increase in the intensity of explosion has increased the base reaction force in all panels.
      Citation: International Journal of Protective Structures
      PubDate: 2023-11-08T02:08:37Z
      DOI: 10.1177/20414196231212511
       
  • Dynamic analysis of precast ultra-high performance concrete tunnel under
           internal explosion

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      Authors: Viet-Chinh Mai, Ngoc Quang Vu, Van Tu Nguyen, Xuan Dai Nguyen
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Underground structures hold great significance in the infrastructure of modern society. With the rapid construction of such facilities, the possibility of explosions occurring inside these structures due to unforeseen accidents or deliberate acts cannot be ignored. Past catastrophic events have demonstrated the necessity of implementing anti-blast design for underground structures, particularly in vulnerable locations. This promotes investigations into the behavior of underground structures subjected to internal explosions. For the first time, a thorough simulation model is developed using the multi-material Coupled Eulerian–Lagrangian approach to examine a full-scale precast ultra-high performance concrete (UHPC) tunnel under internal explosion. The precast tunnel structure closely resembles real construction configurations. The simulation model takes into account the simultaneous interaction between the tunnel and the surrounding soil. The accuracy of the suggested simulation model is validated against experimental results. For various explosive charge weights, tunnel lining thicknesses, materials, and tunnel shapes, extensive parametric simulations are conducted. Results obtained highlighted UHPC's superiority as a substitute for conventional concrete due to its strong blast-resistant capacity. The findings from this research also shed light on the precast UHPC tunnel's structural response to an interior explosion, that can assist designers and managers choose the best design for blast protection.
      Citation: International Journal of Protective Structures
      PubDate: 2023-09-27T07:22:29Z
      DOI: 10.1177/20414196231203402
       
  • Layout considerations on compound survival shelters for blast mitigation:
           A finite-element approach

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      Authors: Andreia Caçoilo, Rodrigo Mourão, David Lecompte, Filipe Teixeira-Dias
      Abstract: International Journal of Protective Structures, Ahead of Print.
      The safety of both military personnel and equipment in unstable regions has for a long time been a major issue and concern. Protective shelters with multiple configurations have been widely used to meet safety requirements. Since military compounds are subjected to different types of threats, such as the detonation of improvised explosive devices (IED), a good understanding of the response of such shielding structures to blast waves is critical. A three-dimensional finite element (FE) model of a corner-entry ISO 20 ft container HESCO-Bastion survival shelter is developed, validated and tested under the external detonation of explosive charges. The FE model is validated against experimental data and used to investigate the protective performance of the shelter by considering several design-related parameters, such as charge location, roof extension, interior corridor dimensions and the effect of venting and its location. Results are discussed in terms of peak overpressure and maximum impulse at discrete locations around the container, and it is found that the shelter is the least efficient in mitigating the blast load propagation when the explosive material is at an angle of 45° to the entrance. Also, while the protective roof at the entrance plays a significant role in protecting the container from air-borne threats, it is observed that it contributes to higher pressure and impulse data within the shelter, for detonations at ground level, with impulse amplifications as high as 94% when fully covering the entrance area. Contrarily, varying the distance between the container and the HESCO-Bastions is found to have minimal impact on the impulse, while naturally decreasing the peak pressure for increasing distances. Venting (through openings) can lead to up to 95% reduction in the peak pressure, whilst not affecting the impulse.
      Citation: International Journal of Protective Structures
      PubDate: 2023-09-21T11:16:45Z
      DOI: 10.1177/20414196231197701
       
  • Experimental evaluation of the thermal effect on dynamic behavior of
           travertine rock

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      Authors: Majid Noorian-Bidgoli, Behnam Behnia
      Abstract: International Journal of Protective Structures, Ahead of Print.
      When an engineering structure regarding a rock is affected by dynamic loads (due to the occurrence of natural hazards, such as earthquakes and landslides, or man-made hazards, such as explosions or impacts), correct prediction of changes in the strength behavior and deformability of the rock relative to its static state is necessary for reducing the damages and costs. On the other hand, rocks are always influenced by environmental conditions, such as temperature changes due to fire and weather during their lifetime, which should be considered when using them. In these cases, the mechanical behavior of the rock can usually be determined under different loading and environmental conditions using stress–strain curves. This study investigates rocks’ dynamic strength and deformability behavior at different loading rates and temperatures. For this purpose, 30 travertine rock samples from the Torshab mine, located in the Markazi province of Iran, were first heated up to 100°C, 200°C, 400°C, 800°C, and 1000°C (six temperatures), and then subjected under the impact pressure with different loading rates from (five) 11 m/s to 15 m/s using the split Hopkinson pressure bar test. Comparing the obtained dynamic stress–strain curve shows that at a constant loading rate, increasing the temperature, especially at higher temperatures, reduces the dynamic strength and increases the rock’s deformability. Moreover, in all cases, at a constant temperature, increasing the loading rate, especially at higher rates, increases the rock’s dynamic strength and deformability.
      Citation: International Journal of Protective Structures
      PubDate: 2023-09-08T11:50:26Z
      DOI: 10.1177/20414196231192680
       
  • Numerical procedure to determine the performance and structural response
           of passive shock wave safety valves under blast loading

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      Authors: Christian Jenni, Tim Altorfer, Sven Düzel, Mirco Ganz, David Denzler, Frank Tillenkamp, André Zahnd, Lorenz Brenner
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Traditional protective structures are usually equipped with ventilation systems. Main components of the latter are passive air blast safety valves. Their purpose in case of an explosive event outside the structure is to significantly reduce the blast pressure leakage into the structure in order to protect human individuals as well as technical installations. Until now, the performance determination of such valves is mostly realized by means of experimental tests in a shock tube. Considering industrial and modern civil protection applications with their practical implementation, additional methods are required to gain further insights into the behaviour of different valve closing mechanisms and to support novel developments as well as error analysis. For this reason, a practice-oriented procedure is presented, with the aim to extend the assessment of the closing behaviour and blast pressure leakage of passive air blast safety valves and the structural behaviour by numerical simulations. In a first preliminary step, potential software solutions have been evaluated based on literature research and expert knowledge. After evaluation of the obtained results, two different software pairs (fluid dynamic as well as structural dynamic tools) have been tested by carrying out indirectly coupled numerical simulations. The software pair APOLLO Blastsimulator & LS-DYNA achieved satisfactory results with the indirect coupling, so that direct fully coupled FSI simulations were additionally performed. To cover a broad range of blast safety valve applications, two different suitable test cases have been considered. In comparison to the experimental results, good agreement was achieved when analysing the pressure–time history of the blast pressure leakage and the closing time of the safety valve. Furthermore, the latter was confirmed by high-speed camera registrations during blast loading.
      Citation: International Journal of Protective Structures
      PubDate: 2023-09-04T07:08:48Z
      DOI: 10.1177/20414196231197702
       
  • Mitigating casualty risks from primary fragmentation hazards

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      Authors: Hao Qin, Mark G Stewart
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Primary fragmentation from detonation of high-explosive metal-cased munitions imposes significant risks to the safety of related personnel and the public. Barricades or other protective structures are commonly used to stop fragments and reduce casualty risks caused by detonated munitions when a sufficient safety distance cannot be guaranteed. This study aims to provide decision support for the positioning of barricades that can reasonably mitigate primary fragmentation hazards from the detonation of large calibre munitions using a probabilistic risk assessment approach. This approach enables a stochastic characterization of fragment ejections, stacking effects, fragment trajectories, human vulnerability and fragment hazard reduction by barricade. In a case study, the assessments of casualty risks and effectiveness of barricades were conducted for a single and a pallet of 155 mm projectiles. It was found that barricades with heights exceeding the height of munitions can significantly reduce the hazardous fragment densities and casualty risks beyond the barricade. The benefit of increasing the barricade height becomes marginal when it exceeds the height of munitions.
      Citation: International Journal of Protective Structures
      PubDate: 2023-08-31T05:17:31Z
      DOI: 10.1177/20414196231198128
       
  • Deep learning-based analysis to identify fluid-structure interaction
           effects during the response of blast-loaded plates

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      Authors: Luca Lomazzi, David Morin, Francesco Cadini, Andrea Manes, Vegard Aune
      Abstract: International Journal of Protective Structures, Ahead of Print.
      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.
      Citation: International Journal of Protective Structures
      PubDate: 2023-08-30T01:50:55Z
      DOI: 10.1177/20414196231198259
       
  • Numerical modelling of blast mitigation of pre-fractal obstacles

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      Authors: Omar Ghareeb Alshammari, Obed Samuelraj Isaac, Samuel David Clarke, Samuel Edward Rigby
      Abstract: International Journal of Protective Structures, Ahead of Print.
      The mechanics of downstream blast wave attenuation caused by interaction with obstacles arranged into a pre-fractal shape based on the Sierpinski carpet was numerically investigated using a high-fidelity CFD solver. The blast mitigation was qualitatively and quantitatively assessed for four pre-fractal iterations at three different scaled distances (Z = 1.87, 2.24, 2.99 m/kg1/3). Mitigation was seen to occur in zones associated with the location of destructive wave interference patterns in the downstream region. Crucially, these zones were found to widen spatially with increasing pre-fractal iteration, and strong shock-shock interactions that result in load amplification, commonly encountered in downstream regions of a solitary block-like obstacle, were not observed for the more fractal-like obstacles. The mechanisms of attenuation are explored in terms of wave impedance. It is found that pre-fractals reduce wave transmission in the downstream, increase reflection of the blast wave, and enhance trapping within the confines of the pre-fractal obstacle, dramatically changing the directionality and hence the strength of the transmitted wave. Reductions in peak pressure of up to 60% and peak specific impulse of up to 40% were recorded for the highest iteration pre-fractal, that is, obstacles that most closely represent a true fractal, thereby highlighting the effectiveness of such shapes for protective structure design for improved blast mitigation.
      Citation: International Journal of Protective Structures
      PubDate: 2023-08-01T08:22:49Z
      DOI: 10.1177/20414196231192676
       
  • Investigating the effect of ceramic-polyurea-aluminum layers on ballistic
           performance of composite target

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      Authors: S Jafari, A Alavi Nia
      Abstract: International Journal of Protective Structures, Ahead of Print.
      In this research, the ballistic performance of ceramic-polyurea-aluminum composite targets under the impact of flat-nose projectile was investigated for different thicknesses. The relevant experiments were designed based on the thickness of the layers and the effect of their configuration was explored. Experimental tests were carried out using two types of gas gun devices with different calibers. Residual velocity of the projectile was extracted using ls-dyna software for all targets and compared with the experimental data and after validation, the ballistic limit velocity was extracted. Taguchi method was used to design experiments and optimization and ballistic limit velocity, surface density, and strength-to-weight ratio were considered as objective functions. Moreover, the residual velocity of the projectile, damage mechanism of layers, the diameter of the hole at the back layer, central displacement of the back layer, absorbed energy, and changes in the projectile velocity were also investigated. Based on the numerical results, ceramic had the greatest effect on reducing the velocity of the projectile (approximately between 55 and 65%). Strength-to-weight ratio and armor weight were considered as two objective functions in the optimization. The effect of each of the armor materials on the target functions was investigated. According to the results, ceramic had the greatest effect on increasing the strength-to-weight ratio (about 83.88%), and polyurea had the least effect (about 14.09%) on increasing the total weight of the armor.
      Citation: International Journal of Protective Structures
      PubDate: 2023-07-14T10:48:50Z
      DOI: 10.1177/20414196231184585
       
  • Quasi-static compressive performance of 3D printed polymer composite
           cellular cubic structures-An experimental study

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      Authors: A Praveen Kumar, Ma Quanjin
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Light weight cellular structures have gained extensive attention in the impact energy absorption applications owing to their superior specific strength and excellent crashworthiness characteristics. The main objective of the present research work is to utilize this benefit to tailor and to improve the structural design and material type of cellular structures for crashworthiness applications. Cubic structures with four different types of design patterns such as concave, convex, hyperbola, and hexagon were proposed and fabricated through three-dimensional (3D) printing technique. Four polymeric filament materials such as Poly lactic acid (PLA), Acrylonitrile butadiene styrene (ABS), PLA mixed carbon fiber (PLA/CF), and Polyethylene terephthalate glycol (PETG), mixed carbon fiber (PETG/CF) were utilized. Accordingly, the compression tests were performed on the fabricated cellular cubic structures under quasi-static loading to examine the effect of design pattern, and material types on the compressive behavior and energy absorbing characteristics. The results revealed that the convex design pattern of 3D printed PETG/CF cubic structure showed the significant energy absorbing characteristics compared to the other three design patterns. It is emphasized that the proposed 3D printed cubic cellular structures have great prospective to substitute the traditional energy absorbing structures in automotive vehicles and high speed trains.
      Citation: International Journal of Protective Structures
      PubDate: 2023-07-04T02:46:34Z
      DOI: 10.1177/20414196231187004
       
  • Influence of prestressing force on performance of concrete plates under
           impact loading

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      Authors: Vimal Kumar, MA Iqbal, AK Mittal
      Abstract: International Journal of Protective Structures, Ahead of Print.
      An experimental and numerical study has been performed to explore the performance of one-way pretensioned concrete plates against impact loading. The impact resistance, experimental results and damage within the pretensioned concrete have been compared with the non-pretensioned concrete. The plate specimens of concrete grades M40 and M60 have been pretensioned to prestress level 10 and 20% of the compressive strength of the concrete. While, all the tendons employed in the non-pretensioned concrete were kept unstressed. The plates were struck at the mid-span by a steel mass (242.85 kg) dropped from 0.5 to 1.0 m heights. The numerical simulations have been executed using explicit finite element code considering the Holmquist–Johnson–Cook (HJC) and the metal plasticity model for concrete and steel, correspondingly. The performance of the plates is governed by the grade of concrete, impact energy and level of the prestress within the concrete. The induced prestress within the concrete enhanced the stiffness and, consequently, the impact resistance of the pretensioned concrete plates. The pretensioned concrete hence witnessed increased impact force and reduced deflection by 18.1% and 11.0%, correspondingly, compared to the non-pretensioned concrete. The splitting and punching crack within the plates became pronounced once the drop height increased from 0.5 m to 1.0 m. The simulations have estimated the peak impact force and reaction within 19.7% and 15.5% deviation, respectively. The displacement and energy absorption have been calculated using an analytical methodology closely correlated with the actual results within 18% and 14% deviation, respectively. Further, the simulations performed on two-way pretensioned concrete have shown improved performance of the plates witnessing no splitting crack and uniform crack distribution compared to one-way pretensioned concrete.
      Citation: International Journal of Protective Structures
      PubDate: 2023-07-01T03:58:10Z
      DOI: 10.1177/20414196231187003
       
  • Development of a high-performance blast energy-absorbing system for
           building structures

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      Authors: Gabriel de Jesus Gomes, Valter José da Guia Lúcio, Corneliu Cismasiu
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Shock absorbers have been widely used in the automotive and aeronautical industries for many years. Inspired on these devices, the paper presents an analytical and numerical assessment of a high performance protective system for building structures against blast loads, which is composed of a shielding element connected to the main structure, at the floor levels, through ductile Energy Absorbing Connectors (EACs). The EACs exploit the external tube inversion mechanism to absorb a significant part of the imparted kinetic energy from the blast wave. While the system prototype has been developed in laboratory, it was characterized and tested in a full-scale blast testing campaign. A validated finite element model was used next to analyze its performance in a more demanding design scenario. The introduction of EACs notably reduces the peak horizontal loads and the kinetic energy transferred to the protected structure, being expected a significant reduction of the stresses in the supporting vertical elements, in addition to the protection of structural and non-structural members. These results encourage further studies of the presented protective system that can be potentially employed for a large variety of blast threat scenarios, especially when increasing the stand-off is not a possible/viable option and sensitive facilities have to be protected.
      Citation: International Journal of Protective Structures
      PubDate: 2023-06-29T06:20:15Z
      DOI: 10.1177/20414196231183006
       
  • Non-parametric characterization of blast loads

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      Authors: Matthew R Kirchner, Shawnasie R Kirchner, Adam A Dennis, Samuel E Rigby
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Mathematical analysis of blast pressures has typically involved the empirical fitting of parametric models, which assumes a specific function shape. In reality, the true shape of the blast pressure is unknown and may lack a parametric form, particularly in the negative phase following arrival of the secondary shock. In this work, we develop a non-parametric (NP) representation that makes few assumptions and relies on the observed experimental data to fit a unique and previously unknown model. This differs from traditional approaches by not arbitrarily selecting a single, restrictive class of functions and estimating a minimal set of parameters, but rather estimating the underlying function class for which the blast pressure is generated; learning the model directly from the observed data. The method was applied to experimental blast measurements and the NP estimates matched the experimental data with a high degree of accuracy, both qualitatively and quantitatively. The NP approach was shown to significantly outperform other commonly used approaches, near-perfectly track the entire pressure and specific impulse history and predicting experimental peak specific impulse to within ±0.5% in all cases (compared to ±5.0% for a trained artificial neural network (ANN) and ±7.5% for the UFC semi-empirical approach). The NP approach predicts experimental net specific impulses (positive and negative phases combined) with a maximum variation of 2.7%, compared to maximum variations of −116% and 55% for the UFC and ANN approaches, respectively. Since the framework is probabilistic in nature, it can naturally account for random noise in sensor measurements, which are typically more pronounced in blast experiments than many other machine learning applications.
      Citation: International Journal of Protective Structures
      PubDate: 2023-06-26T04:00:09Z
      DOI: 10.1177/20414196231184581
       
  • The Direction-encoded Neural Network: A machine learning approach to
           rapidly predict blast loading in obstructed environments

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      Authors: Adam A Dennis, Sam E Rigby
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Machine learning (ML) methods are becoming more prominent in blast engineering applications, with their adaptability to new scenarios and rapid computation times providing key benefits when compared to empirical methods and physics-based approaches, respectively. However, ML approaches commonly used for blast analyses are regularly provided with inputs relating to domain-specific parameters, restricting their use beyond the initial problem set and reducing their generality. This article presents the ‘Direction-encoded Neural Network’ (DeNN); a novel way to structure an Artificial Neural Network (ANN) to predict blast loading in obstructed environments. Each point of interest (POI) is represented by the proximity to its surroundings and the shortest travel path of the blast wave in order to prime the network to learn the underlying physics of the problem. Furthermore, a bespoke wave reflection equation creates a zone of influence around each point so that obstacles are only captured in the network’s inputs if they would alter the path of the wave. It is shown that the DeNN can predict peak overpressures with mean absolute errors ∼5 kPa for unseen, complex domains of any shape or size, when compared to the results from physics-based numerical models with ∼30 times the solution time of the DeNN. The network is used to develop maps of likely human injury following detonation of a high explosive in an internal environment, with eardrum rupture levels being correctly predicted for over 93% of unseen test points. It is therefore highly suited for use in probabilistic, risk-based analyses which are currently impractical due to excessive computational cost.
      Citation: International Journal of Protective Structures
      PubDate: 2023-06-01T11:38:52Z
      DOI: 10.1177/20414196231177364
       
  • Exploratory study on the use of bi-stable supports for the impact
           protection of point-fixed glazing systems

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      Authors: Hugo Bento Rebelo, Beatriz Assunção, Chiara Bedon, Filipe Amarante dos Santos
      Abstract: International Journal of Protective Structures, Ahead of Print.
      This paper is focused on the study of innovative bi-stable supports to improve the impact performance of point-fixed glass panels, for typical use in facades. To mitigate the effects of impact and reduce potential risk for people, the introduction of innovative, bi-stable, mitigation devices between the fixing system and the primary building structure is addressed. The proposed dissipative system is able to control and minimise the input force which is transmitted to the primary building, controlling the damage around the supports and preventing the detachment of the glass panels. Based on LS-Dyna Finite-Element (FE) models, the proposed protection system is designed to have a snap-through behaviour under impact. The performance of the system is quantified for two different glazing systems, which are numerically investigated under various impact configurations.
      Citation: International Journal of Protective Structures
      PubDate: 2023-06-01T11:24:45Z
      DOI: 10.1177/20414196231175979
       
  • On the estimation of near-field air blast peak overpressure from
           cylindrical charges

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      Authors: J Liu, CZ Gao, ZY Sun, JW Yin
      Abstract: International Journal of Protective Structures, Ahead of Print.
      In the near field, the air blast peak overpressure from cylindrical charges may vary by several times with angles at the same scaled distance. We propose an estimation equation for the peak overpressure from cylindrical charges, which can predict the peak overpressure from cylindrical charges at any positions in the near field. The estimation equation is in the form of piecewise function which contains three variables of length-to-diameter ratio, angle and scaled distance, and the applicability of our estimation equation is verified by experiment and simulation. After preliminary verification, the application range of length-to-diameter ratio of cylindrical charge is [math] and that of scaled distance is [math]. The estimation equation can be rapidly applied to the assessment of near-field target damage and protection against air blast from cylindrical charges, which is a significant supplement to the traditional empirical equations for spherical charge.
      Citation: International Journal of Protective Structures
      PubDate: 2023-05-19T09:48:56Z
      DOI: 10.1177/20414196231177358
       
  • Elasto-plastic analysis of foundations during emergency shutdown due to
           blast loading

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      Authors: Kirtika Samanta, Priti Maheshwari
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Behaviour of machine foundations is investigated in this study under harmonic loading with varying frequency and pulse loading. Owing to excessive vibrations from the pulse, the machine encounters an emergency shutdown where the machine’s exciting frequency reduces to zero exponentially. The analysis is performed considering an elastic plastic single degree of freedom system with hardening and softening behaviour. Two cases are analysed depending on the time of application of pulse loading to the foundation system. For both the cases, the governing equations of motion are acquired and solved numerically using the fourth order Runge-Kutta method. Using these solutions, displacement-time graphs are obtained for a variety of parameters such as time constant, hardening/softening index, mass of machine and the foundation block, stiffness, pulse load magnitude, damping ratio and decay coefficient to study their influence on the behaviour of the machine-foundation system. The study helps in predicting the dynamic response of foundations under the emergency shutdown conditions due to pulse loading. Further, these also help in taking the decision if there exists a need for vibration barriers to have the displacements well within the permissible limits.
      Citation: International Journal of Protective Structures
      PubDate: 2023-05-11T11:14:50Z
      DOI: 10.1177/20414196231174916
       
  • Simulation of blast-induced rock tunnel damage using a 3D numerical model

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      Authors: Ayham Ali Salamy, Ibrahim Hammoud
      Abstract: International Journal of Protective Structures, Ahead of Print.
      The field tests conducted by the American Engineering Research Associates (ERA) provided important results about the distribution and extension of the damage zones and the failure area that occurred in unlined tunnels as a result of buried explosions in the rock mass surrounding these tunnels. Despite the importance of these results, they did not include specific values for the failure thickness and the fracture angle in the damaged tunnel sections. In the current study, a 3D numerical model is used to simulate one of ERA’s tests using ABAQUS. In this model, the impact of a buried explosion on a tunnel located at (5m) away from the center of the detonation is studied. The results of this model are in good agreement with the published results of ERA’s tests. In addition, the current numerical results give complete values for the change in the failure thickness and the fracture angle over the entire length of the damaged zones of the tunnel. The results of the current study show that the thickness of the failure remains almost constant beyond damage zone 1, while the angle of the fracture decreases remarkably as the charge-to-tunnel distance increases, which causes a decrease in the failure area.
      Citation: International Journal of Protective Structures
      PubDate: 2023-04-04T11:25:09Z
      DOI: 10.1177/20414196231167596
       
  • Numerical study of a near-field explosion using arbitrary
           Lagrangian–Eulerian mapping technique

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      Authors: Cheng-Wei Hung, Ying-Kuan Tsai, Li-Kai Chien, Sheng-Jung Pi
      Abstract: International Journal of Protective Structures, Ahead of Print.
      This study adopted the LS-DYNA mapping algorithm to implement a numerical simulation of a near-surface burst and steel plate non-contact explosion experiments. The rationality and reliability of the mapping technique used in the numerical simulation were validated by a comparison between the experiments and the numerical simulation. The findings showed that the numerical simulation result was consistent with the experimental blast attenuation, meaning the numerical mapping technique could effectively enhance the simulation accuracy and could reflect the experimental blast wave propagation.
      Citation: International Journal of Protective Structures
      PubDate: 2023-03-29T01:16:16Z
      DOI: 10.1177/20414196231166067
       
  • Evaluation of automatic versus material test-based calibrations of
           concrete models for ballistic impact simulations

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      Authors: Andria Antoniou, Tore Børvik, Martin Kristoffersen
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Concrete is used for protective structures all over the world. Accurate response estimates to a given threat is vital for designing such structures. Concrete models often require numerous input parameters for which sufficient experimental data can be challenging to obtain. Some models are accompanied by parameter generators which use the unconfined compression strength to extrapolate the remainder of the parameters based on experimental databases. This study investigates simulation of ballistic impact on high-strength concrete with 75 MPa nominal unconfined cylindrical compressive strength. The first objective is to investigate the accuracy parameter generators to produce input data for commonly used concrete material models. The second objective is to establish and evaluate a simplified parameter calibration procedure based on standard material experiments and data from the literature. The results employing parameter generators varied notably between the models while still giving decent ballpark estimates. The parameters obtained from inverse modelling of standardized material tests improved the results significantly. The findings of this study recommend caution when using automatic parameter generators. Although a detailed calibration of these concrete models is complicated, a simplified calibration gives reasonable predictions, making this the advisable approach for designing concrete protective structures.
      Citation: International Journal of Protective Structures
      PubDate: 2023-03-24T01:10:21Z
      DOI: 10.1177/20414196231164431
       
  • Pounding response of concrete rods with rough impacting surfaces

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      Authors: Vladimir R. Feldgun, David Z. Yankelevsky, Yuri S. Karinski
      Abstract: International Journal of Protective Structures, Ahead of Print.
      This paper presents theoretical research that is supported by experimental data, aiming at investigating and explaining unexpected experimental results that were obtained on low velocity pounding response of adjacent concrete rods. The experimental results indicate inelastic response expressed by the post-impact relative velocity and coefficient of restitution that is smaller than one, although elastic response is expected. This research conjectures that the inspected response is due to the roughness of the impacting surfaces. A theoretical analytical and a following numerical investigation examined the behavior of the surface roughness represented by small size asperities in an idealized model. Analysis of the asperity behavior clarified its inelastic behavior that affects major parameters on the response. An integrated parameter has been identified, which includes major parameters of the asperity affecting the dynamic behavior and helping to relate the geometrical parameters of an asperity with the measured pounding data. It was found that asperities may explain the energy absorption during low velocity pounding. This explains the lower coefficient of restitution than expected even at low velocity pounding. An effective and simple analytical approach is developed to simulate the rods collision with an idealized surface asperity and demonstrates the role of the asperities on a realistic simulation of the experimental result.
      Citation: International Journal of Protective Structures
      PubDate: 2023-03-23T12:47:13Z
      DOI: 10.1177/20414196231166017
       
  • Modeling of crashworthy foam mounted braced unreinforced brick masonry
           wall and prediction of anti-blast performance

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      Authors: S. M. Anas, Mohd Shariq, Mehtab Alam, Mohammad Umair
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Explosions are continually occurring in many parts of the world endangering human lives and seriously affecting the health of infrastructures and facilities. Low-rise buildings having a height of fewer than 13 m are load-bearing structures generally made of unreinforced masonry (URM), particularly in semi-urban areas, villages, and war-prone border areas. Many structures of importance including buildings constructed in the pre- and post-independence era of courts, monuments, etc., are masonry load-bearing structures. URM is also used as non–load-bearing partition walls and compound/boundary walls. Such walls are susceptible to out-of-plane blast loading. Under such loadings, these walls fail to survive and thus either get severely damaged or collapsed, jeopardizing the stability of the entire structure. Resistance of masonry walls against blast loading is vital for the safety of the building and its users as injuries sustained and casualties are generally not caused due to explosion, but by the brittle dynamic fracture and fragments of masonry walls, window glass panes shattering, and other secondary objects propelled as missiles by the blasts. In general, buildings are not designed for blast loading. For the safety of the building users, it is imperative that the walls must withstand such short-duration high-magnitude extreme loadings without not only undergoing catastrophic collapse but also not producing deadly fragments which could cause grievous injuries to the users. To protect URM walls from high-intensity blast waves, an out-of-box wall protecting technique using foams of polymer (e.g., polyurethane) and metals namely; aluminum and titanium, is considered on the face of the wall exposed to the blast pressure. This study describes a numerical technique implemented in ABAQUS/Explicit software to predict the overall anti-blast performance of URM wall strengthened externally with the above three different crashworthy foams. For this purpose, a braced URM wall made of clay bricks, with two transverse bracing walls one at each end on the same side, tested experimentally by Badshah et al. in the year 2021 under the chemical explosive loads of 4.34 kg and 7.39 kg-TNT, respectively, at scaled distances 2.19 m/kg1/3 and 1.83 m/kg1/3 is considered as the reference model and is validated against the test observations. Explosion load is modeled with ABAQUS built-in ConWep simulation program to simulate the wall-explosion wave interactions in the free field. Material nonlinearities of the brickwork have been attributed to bricks, joint-mortar, and brick-mortar interfaces through constitutive laws considering strain-rate effects. The foams are modeled using ABAQUS’s inbuilt Crushable Foam Plasticity Hardening model considering foam hardening and rate-dependent schemes. Results show that the higher Young’s modulus and inelastic stiffness of the foams contribute to dissipating more explosion energy and improve the resistance of the walls from savage explosions.
      Citation: International Journal of Protective Structures
      PubDate: 2023-03-17T12:53:21Z
      DOI: 10.1177/20414196231164432
       
  • Assessment of the ballistic impact response of Cor-Tuf UHPC concrete using
           the HJC constitutive model

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      Authors: Richard A Perkins, Chris Duncan, Daniel Johnson, Tonya Stone, Jesse Sherburn, Mei Chandler, Robert Moser, Bhasker Paliwal, Raj K Prabhu, Youssef Hammi
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Concrete offers superior strength in compressive loadings and is implemented for many applications. The high compressive strengths enable concrete to resist high strain rate loading scenarios such as ballistic impacts. A variety of concrete denoted as Cor-Tuf, which is classified as ultra-high-performance concrete with a compressive strength of 210 MPa, is evaluated in this study. The response of this concrete is assessed through a finite element analysis under the high strain rate loadings of ballistic impacts. To capture the response of the concrete, a plasticity and damage constitutive model denoted as the HJC model is implemented. The parameters of this model are calibrated to the Cor-Tuf concrete using confined compression experiments, unconfined compression experiments, and shock experiments. The concrete target is impacted at speeds between 610 m/s through 1112 m/s, and the results are compared to existing experimental data. Our results show that the HJC model can predict the response of this impact to the Cor-Tuf concrete targets as an average error of 5.85% is found. The results of this study present parameters which can be implemented with the HJC concrete model for future studies to model the response of the Cor-Tuf UHPC.
      Citation: International Journal of Protective Structures
      PubDate: 2023-02-28T09:30:43Z
      DOI: 10.1177/20414196231160235
       
  • Design, development, and calibration of split Hopkinson pressure bar
           system for Dynamic material characterization of concrete

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      Authors: Mohammad Mohsin Khan, Mohd Ashraf Iqbal
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Split Hopkinson pressure bar (SHPB) system is significantly used for dynamic material characterization in the range of strain rates 102–104 s-1; however, there is no standard design methodology or readily available technique for the development of this apparatus. The objective of this study is to present a detailed design, development and calibration of SHPB apparatus for dynamic material characterization of concrete in compression. The calibration of the loading and bar components has been presented with the help of experimental results and validated following an analytical approach for one-dimensional stress wave propagation. The experimental pulse duration, 124.5 microsecond, and elastic wave speed, 4820 m/s, was measured with 2% deviation from the analytical results. Under three different impact velocities, a minimum 1.09% and maximum 4.14% decrement was observed in the incident wave as compared to analytical formulation. The recorded strain signals were captured in the transmission bar with a decrement of 1, 3, and 3.3% in peak strain when compared to the incident bar, at 4.5, 4.9, and 5.7 m/s impact velocities. The incident and transmission bars had almost identical wave characteristics demonstrating that the bar system has been perfectly and precisely aligned, and almost complete wave transfer is seen to have occurred. Experiments performed on M35 concrete specimens using the developed SHPB setup have been presented and discussed. The results demonstrated that the developed SHPB setup is capable to provide accurate results for the dynamic material characterization of concrete at high strain rate loading.
      Citation: International Journal of Protective Structures
      PubDate: 2023-02-08T09:34:19Z
      DOI: 10.1177/20414196231155947
       
  • Safety assessment for a ballast railway induced by underground subway
           tunnel blasting: A case study

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      Authors: Bowen Zhao, Nan Jiang, Chuanbo Zhou, Yingkang Yao, Wenbin Zhou, Zhongwei Cai
      Abstract: International Journal of Protective Structures, Ahead of Print.
      Modern railroad infrastructure is subject to blast vibrations. The dynamic safety of an operating railroad under the influence of tunnel blasting is a primary problem for metro development in urban areas. In this paper, the blasting excavation of Wuhan Metro Line 5 was selected as a case. The ballast rail- sleeper- ballast bed composite structure numerical model was developed and validated in order to evaluate the ballast railway’s safety. The smoothed particle hydrodynamics element was chosen to replicate the ballast bed due to the instability and unpredictability of the ballast bed constructed from crushed stone. Further analysis was conducted on the dynamic response characteristics of the ballast rail-sleeper-ballast bed composite structure. On the basis of the parameter calculation and analysis, a prediction model of the blast vibration velocity of the ballast rail under blasting conditions was developed. Next, the rail was simulated as a semi-infinite Euler beam and placed on the Kelvin foundation to calculate the rail displacement at the train’s limited operation speed. By substituting the maximum rail displacement when the train is running at maximum speed into the rail velocity prediction model, it is possible to determine the maximum blast velocity that the rail can withstand in this instance. In this case, the ballast bed, sleeper, and ballast rail were also deemed safe.
      Citation: International Journal of Protective Structures
      PubDate: 2023-01-09T05:35:04Z
      DOI: 10.1177/20414196221150661
       
  • Far-field positive phase blast parameter characterisation of RDX and PETN
           based explosives

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      Authors: Dain G. Farrimond, Scott Woolford, Andrew Tyas, Sam E. Rigby, Samuel D. Clarke, Andrew Barr, Mark Whittaker, Dan J. Pope
      Abstract: International Journal of Protective Structures, Ahead of Print.
      A significant amount of scientific effort has been dedicated to measuring and understanding the effects of explosions, leading to the development of semi-empirical methods for rapid prediction of blast load parameters. The most well-known of these, termed the Kingery and Bulmash method, makes use of polylogarithmic curves derived from a compilation of medium to large scale experimental tests performed over many decades. However, there is still no general consensus on the accuracy and validity of this approach, despite some researchers reporting consistently high levels of agreement. Further, it is still not known whether blast loading can be considered deterministic, or whether it is intrinsically variable, the extent of this variability, and the range and scales over which these variations are observed. This article critically reviews historic and contemporary blast experiments, including newly generated arena tests with RDX and PETN-based explosives, with a view to demonstrating the accuracy with which blast load parameters can be predicted using semi-empirical approaches.
      Citation: International Journal of Protective Structures
      PubDate: 2023-01-05T10:50:17Z
      DOI: 10.1177/20414196221149752
       
 
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