Pub Date : 2024-01-02DOI: 10.1177/20414196231225813
Z. Rosenberg, Y. Vayig
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.
{"title":"On the penetration of rigid spheres in metallic targets","authors":"Z. Rosenberg, Y. Vayig","doi":"10.1177/20414196231225813","DOIUrl":"https://doi.org/10.1177/20414196231225813","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139391616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-11DOI: 10.1177/20414196231216751
C. Sauer, Jan Burtsche, Andreas Heine, Christoph Roller, Werner Riedel
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.
{"title":"High-velocity impact experiments and quantitative damage evaluation for finite ultra-high-performance concrete targets","authors":"C. Sauer, Jan Burtsche, Andreas Heine, Christoph Roller, Werner Riedel","doi":"10.1177/20414196231216751","DOIUrl":"https://doi.org/10.1177/20414196231216751","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138980284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-08DOI: 10.1177/20414196231212511
Masoud Abedini, Chunwei Zhang
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.
{"title":"Dynamic performance of ultra-high performance fiber-reinforced concrete panel exposed to explosive loading","authors":"Masoud Abedini, Chunwei Zhang","doi":"10.1177/20414196231212511","DOIUrl":"https://doi.org/10.1177/20414196231212511","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135390302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-27DOI: 10.1177/20414196231203402
Viet-Chinh Mai, Ngoc Quang Vu, Van Tu Nguyen, Xuan Dai Nguyen
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.
{"title":"Dynamic analysis of precast ultra-high performance concrete tunnel under internal explosion","authors":"Viet-Chinh Mai, Ngoc Quang Vu, Van Tu Nguyen, Xuan Dai Nguyen","doi":"10.1177/20414196231203402","DOIUrl":"https://doi.org/10.1177/20414196231203402","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135536147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-21DOI: 10.1177/20414196231197701
Andreia Caçoilo, Rodrigo Mourão, David Lecompte, Filipe Teixeira-Dias
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.
{"title":"Layout considerations on compound survival shelters for blast mitigation: A finite-element approach","authors":"Andreia Caçoilo, Rodrigo Mourão, David Lecompte, Filipe Teixeira-Dias","doi":"10.1177/20414196231197701","DOIUrl":"https://doi.org/10.1177/20414196231197701","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136129250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-08DOI: 10.1177/20414196231192680
Majid Noorian-Bidgoli, Behnam Behnia
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.
{"title":"Experimental evaluation of the thermal effect on dynamic behavior of travertine rock","authors":"Majid Noorian-Bidgoli, Behnam Behnia","doi":"10.1177/20414196231192680","DOIUrl":"https://doi.org/10.1177/20414196231192680","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45400798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-04DOI: 10.1177/20414196231197702
Christian Jenni, Tim Altorfer, Sven Düzel, Mirco Ganz, David Denzler, F. Tillenkamp, André Zahnd, Lorenz Brenner
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.
{"title":"Numerical procedure to determine the performance and structural response of passive shock wave safety valves under blast loading","authors":"Christian Jenni, Tim Altorfer, Sven Düzel, Mirco Ganz, David Denzler, F. Tillenkamp, André Zahnd, Lorenz Brenner","doi":"10.1177/20414196231197702","DOIUrl":"https://doi.org/10.1177/20414196231197702","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45867196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1177/20414196221104143
S. Anas, Meraj Alam, M. Umair
Composite structural members such as concrete-filled double-skin steel tube (CFDSST) and concrete-filled double steel tubular (CFDST) columns are increasingly being utilized in modern structures owing to their capability to integrate the beneficial properties of constituent materials to carry heavy loads as compared to conventional reinforced concrete columns. Axial compression performance of such composite columns has been extensively investigated and available in the open literature. However, their response under impulsive loadings such as those induced by explosions is not very well studied because not many investigations have been conducted on these columns. Performance of composite compression members under short-duration/high-magnitude blast loading is of considerable interest under the prevailing environment of hi-tech wars, subversive activities, and accidental explosions. The recent devastating accidental Ammonium Nitrate explosion at Beirut port (Lebanon), and the ongoing invasion of Ukraine by Russia raise the concern of researchers and engineers for the safety of structural elements/components. In this study, a 3-D finite element model of axially loaded 2500 mm long CFDSST column of ultra-high-strength concrete (170 MPa) is developed in ABAQUS/Explicit-v.6.15 computer code equipped with Concrete Damage Plasticity (CDP) model, and investigation has been carried out for its blast performance under the 50kg-TNT explosive load at a standoff distance of 1.50 m in free-air. The effects of strain rate on the compressive strength of the concrete are considered as per fib Model Code 2010 (R2010) and UFC-3-340-02 (2008). The non-linear behavior of the steel is also taken into account. Damages in the form of (1) a - concrete crushing on the explosion side of the column and b - concrete cracking on the tension side and their spread over the column length, and (2) yielding of tubes are observed. Computational results are validated with the available experimental observations. To improve the column response, the analysis has been extended to investigate the blast performance of axially loaded CFDSST columns with and without core concrete having an inner steel tube of circular/square cross-section and their response have been compared with the equivalent single skin concrete-filled steel tubular circular/square columns of same axial load capacity.
{"title":"Performance of (1) concrete-filled double-skin steel tube with and without core concrete, and (2) concrete-filled steel tubular axially loaded composite columns under close-in blast","authors":"S. Anas, Meraj Alam, M. Umair","doi":"10.1177/20414196221104143","DOIUrl":"https://doi.org/10.1177/20414196221104143","url":null,"abstract":"Composite structural members such as concrete-filled double-skin steel tube (CFDSST) and concrete-filled double steel tubular (CFDST) columns are increasingly being utilized in modern structures owing to their capability to integrate the beneficial properties of constituent materials to carry heavy loads as compared to conventional reinforced concrete columns. Axial compression performance of such composite columns has been extensively investigated and available in the open literature. However, their response under impulsive loadings such as those induced by explosions is not very well studied because not many investigations have been conducted on these columns. Performance of composite compression members under short-duration/high-magnitude blast loading is of considerable interest under the prevailing environment of hi-tech wars, subversive activities, and accidental explosions. The recent devastating accidental Ammonium Nitrate explosion at Beirut port (Lebanon), and the ongoing invasion of Ukraine by Russia raise the concern of researchers and engineers for the safety of structural elements/components. In this study, a 3-D finite element model of axially loaded 2500 mm long CFDSST column of ultra-high-strength concrete (170 MPa) is developed in ABAQUS/Explicit-v.6.15 computer code equipped with Concrete Damage Plasticity (CDP) model, and investigation has been carried out for its blast performance under the 50kg-TNT explosive load at a standoff distance of 1.50 m in free-air. The effects of strain rate on the compressive strength of the concrete are considered as per fib Model Code 2010 (R2010) and UFC-3-340-02 (2008). The non-linear behavior of the steel is also taken into account. Damages in the form of (1) a - concrete crushing on the explosion side of the column and b - concrete cracking on the tension side and their spread over the column length, and (2) yielding of tubes are observed. Computational results are validated with the available experimental observations. To improve the column response, the analysis has been extended to investigate the blast performance of axially loaded CFDSST columns with and without core concrete having an inner steel tube of circular/square cross-section and their response have been compared with the equivalent single skin concrete-filled steel tubular circular/square columns of same axial load capacity.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45306871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-30DOI: 10.1177/20414196231198128
Hao Qin, M. Stewart
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.
{"title":"Mitigating casualty risks from primary fragmentation hazards","authors":"Hao Qin, M. Stewart","doi":"10.1177/20414196231198128","DOIUrl":"https://doi.org/10.1177/20414196231198128","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46775873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-30DOI: 10.1177/20414196231198259
L. Lomazzi, David Morin, F. Cadini, A. Manes, V. Aune
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.
{"title":"Deep learning-based analysis to identify fluid-structure interaction effects during the response of blast-loaded plates","authors":"L. Lomazzi, David Morin, F. Cadini, A. Manes, V. Aune","doi":"10.1177/20414196231198259","DOIUrl":"https://doi.org/10.1177/20414196231198259","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43165266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：