Pub Date : 2024-08-09DOI: 10.1177/20414196241271449
Laura Cannon, Alexander Rogers, Chris Taggart
The term non-ideal air blast (NIAB) refers to any blast propagation other than that in free-air or over a perfectly reflecting surface. NIAB effects in large-scale blast scenarios include phenomena such as shielding and channelling caused by obstacles such as terrain, buildings and vegetation. These effects can alter the loading received by a structure in the path of the blast wave, and, hence, its subsequent response. This study used numerical simulation to investigate the relative significance of various NIAB effects in this respect. The numerical methods employed are discussed, in addition to a summary of the results obtained. It is shown that the presence of terrain or buildings had the most significant impact on blast loading and resulting structural response.
{"title":"Investigating the significance of non-ideal effects in large-scale blast propagation","authors":"Laura Cannon, Alexander Rogers, Chris Taggart","doi":"10.1177/20414196241271449","DOIUrl":"https://doi.org/10.1177/20414196241271449","url":null,"abstract":"The term non-ideal air blast (NIAB) refers to any blast propagation other than that in free-air or over a perfectly reflecting surface. NIAB effects in large-scale blast scenarios include phenomena such as shielding and channelling caused by obstacles such as terrain, buildings and vegetation. These effects can alter the loading received by a structure in the path of the blast wave, and, hence, its subsequent response. This study used numerical simulation to investigate the relative significance of various NIAB effects in this respect. The numerical methods employed are discussed, in addition to a summary of the results obtained. It is shown that the presence of terrain or buildings had the most significant impact on blast loading and resulting structural response.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141922246","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 : 2024-07-19DOI: 10.1177/20414196241264886
Jonas Rudshaug, Tormod Grue, B. S. Elveli
Window facades are heavily used in modern design. To ensure that the facade can withstand sufficiently large blast loads, experimental evaluation of the entire facade is crucial. In this study, we present the High Explosive Blast Simulator (HEBSim), an outdoors modular explosive-driven blast simulator with a large cross-section designed for real-size blast testing of glass facades. To evaluate the performance of HEBSim, we performed two test series, one with a rigid steel plate component and one with deformable laminated glass window components. Pressure sensors were used to measure the overpressure histories for both test series and deformation data was gathered using three-dimensional digital image correlation (3D-DIC) for the window component tests. The test series demonstrated that HEBSim generates planar and repeatable blast load profiles in line with explosive pressure resistance (EPR) classifications for various charge masses. In addition, the window component test series illustrated the stochastic fracture behavior of glass. Based on the presented data, HEBSim is found suitable for blast testing of large glass facades.
{"title":"A high explosive blast simulator","authors":"Jonas Rudshaug, Tormod Grue, B. S. Elveli","doi":"10.1177/20414196241264886","DOIUrl":"https://doi.org/10.1177/20414196241264886","url":null,"abstract":"Window facades are heavily used in modern design. To ensure that the facade can withstand sufficiently large blast loads, experimental evaluation of the entire facade is crucial. In this study, we present the High Explosive Blast Simulator (HEBSim), an outdoors modular explosive-driven blast simulator with a large cross-section designed for real-size blast testing of glass facades. To evaluate the performance of HEBSim, we performed two test series, one with a rigid steel plate component and one with deformable laminated glass window components. Pressure sensors were used to measure the overpressure histories for both test series and deformation data was gathered using three-dimensional digital image correlation (3D-DIC) for the window component tests. The test series demonstrated that HEBSim generates planar and repeatable blast load profiles in line with explosive pressure resistance (EPR) classifications for various charge masses. In addition, the window component test series illustrated the stochastic fracture behavior of glass. Based on the presented data, HEBSim is found suitable for blast testing of large glass facades.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141820969","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 : 2024-06-01DOI: 10.1177/20414196231166017
V. Feldgun, D. Yankelevsky, Y. Karinski
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.
{"title":"Pounding response of concrete rods with rough impacting surfaces","authors":"V. Feldgun, D. Yankelevsky, Y. Karinski","doi":"10.1177/20414196231166017","DOIUrl":"https://doi.org/10.1177/20414196231166017","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141398782","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 : 2024-05-14DOI: 10.1177/20414196241251482
Oleg Vorobiev, Sean Ford
Seismoacoustic wave generation for two consecutive surface chemical explosions of the same yield (approximately 1 ton TNT-equivalent) was studied during the Large Surface Explosion Coupling Experiment (LSECE) conducted at Yucca Flat on the Nevada National Security Site (NNSS) site in alluvium geology. We have performed numerical simulations for both chemical explosions to investigate how the non-central source initiation, site topography and soil mechanical properties affect the evolution of the explosion (fireball and cloud), its crater, and variations in the generated blast waves. The results can be used to improve the understanding of surface explosions and their effects and how those effects can be used to infer source information such as explosive yield and emplacement. We find that the non-central detonation of the explosive cube results in non-axisymmetric blast overpressures which persist through the strong and weak shock regimes, in this case out to 200 m and more. The pattern of the secondary shock (i.e., shock created due to slowing explosive products within the expanding fireball) is also affected and its arrival relative to the main shock and may be indicative of explosive type due to its dependence on the explosive products ratio of heats. Small reflections are visible within the overpressure signal that are most probably due to small artifacts in blast path. Importantly, the fireball growth, cavity generation, and cloud formation also depart from spherical and ideal approximations due to ground interactions and material dependence, which shows the importance of realistic geomaterial models for accurate prediction. The asymmetry in peak overpressure is diminished for the second chemical explosion, which was placed in the crater of the first. Numerical modeling shows that the explosive jetting created by the non-central detonation is reduced upon interaction with the crater walls and this has the effect of making the blast generation more axisymmetric.
{"title":"Airblast observations and near-field modeling of the large surface explosion coupling experiment","authors":"Oleg Vorobiev, Sean Ford","doi":"10.1177/20414196241251482","DOIUrl":"https://doi.org/10.1177/20414196241251482","url":null,"abstract":"Seismoacoustic wave generation for two consecutive surface chemical explosions of the same yield (approximately 1 ton TNT-equivalent) was studied during the Large Surface Explosion Coupling Experiment (LSECE) conducted at Yucca Flat on the Nevada National Security Site (NNSS) site in alluvium geology. We have performed numerical simulations for both chemical explosions to investigate how the non-central source initiation, site topography and soil mechanical properties affect the evolution of the explosion (fireball and cloud), its crater, and variations in the generated blast waves. The results can be used to improve the understanding of surface explosions and their effects and how those effects can be used to infer source information such as explosive yield and emplacement. We find that the non-central detonation of the explosive cube results in non-axisymmetric blast overpressures which persist through the strong and weak shock regimes, in this case out to 200 m and more. The pattern of the secondary shock (i.e., shock created due to slowing explosive products within the expanding fireball) is also affected and its arrival relative to the main shock and may be indicative of explosive type due to its dependence on the explosive products ratio of heats. Small reflections are visible within the overpressure signal that are most probably due to small artifacts in blast path. Importantly, the fireball growth, cavity generation, and cloud formation also depart from spherical and ideal approximations due to ground interactions and material dependence, which shows the importance of realistic geomaterial models for accurate prediction. The asymmetry in peak overpressure is diminished for the second chemical explosion, which was placed in the crater of the first. Numerical modeling shows that the explosive jetting created by the non-central detonation is reduced upon interaction with the crater walls and this has the effect of making the blast generation more axisymmetric.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140978700","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 : 2024-05-09DOI: 10.1177/20414196241252937
Hwee Kiat Yeo, Swee Hong Tan
In this contribution, a series of findings from Computational Fluid Dynamics (CFD) simulations of blast propagation within fully confined spaces are presented. These numerical works have been carried out as part of an ongoing in-house development towards a fast-running method to predict overpressures and impulses arising from detonations within the various configurations of carparks in Singapore. In land-scarce cities like Singapore, carparks are typically located within the same structural footprints and are integrated with other functions of the building to facilitate convenient access. Design of carparks are required to meet statutory provisions with regards to the layout, headroom clearance and safety. To this end, the present research study has adopted a three-stage approach. First, different representative configurations of carparks are determined by making reference to and rationalising based on the prevailing statutory provisions in Singapore. This is then followed by a series of parametric CFD simulations to obtain essential numerical data in order to characterise the blast propagation within the respective partially confined spaces. Finally, several regression models are employed to derive relationships between the critical parameters and the blast data, with the aim of achieving a fast-running predictive method. This paper seeks to provide detailed descriptions of the first and the second stages, as well as to present the comparisons of numerically converged solutions, which are obtained from preliminary CFD simulations using two mesh sizes, against semi-analytical solutions which are calculated based on guidance from UFC 3-340-02 for fully confined detonation as initial reference cases.
{"title":"Development of a fast-running method for prediction of blast propagation in partially confined spaces","authors":"Hwee Kiat Yeo, Swee Hong Tan","doi":"10.1177/20414196241252937","DOIUrl":"https://doi.org/10.1177/20414196241252937","url":null,"abstract":"In this contribution, a series of findings from Computational Fluid Dynamics (CFD) simulations of blast propagation within fully confined spaces are presented. These numerical works have been carried out as part of an ongoing in-house development towards a fast-running method to predict overpressures and impulses arising from detonations within the various configurations of carparks in Singapore. In land-scarce cities like Singapore, carparks are typically located within the same structural footprints and are integrated with other functions of the building to facilitate convenient access. Design of carparks are required to meet statutory provisions with regards to the layout, headroom clearance and safety. To this end, the present research study has adopted a three-stage approach. First, different representative configurations of carparks are determined by making reference to and rationalising based on the prevailing statutory provisions in Singapore. This is then followed by a series of parametric CFD simulations to obtain essential numerical data in order to characterise the blast propagation within the respective partially confined spaces. Finally, several regression models are employed to derive relationships between the critical parameters and the blast data, with the aim of achieving a fast-running predictive method. This paper seeks to provide detailed descriptions of the first and the second stages, as well as to present the comparisons of numerically converged solutions, which are obtained from preliminary CFD simulations using two mesh sizes, against semi-analytical solutions which are calculated based on guidance from UFC 3-340-02 for fully confined detonation as initial reference cases.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140996304","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 : 2024-04-15DOI: 10.1177/20414196241246285
Yingbo Ren, Nan Jiang, Chuan-bo Zhou, Yingkang Yao, Guopeng Lyu
In the context of mitigating the impact of blasting-induced seismic waves on excavation processes and reducing the vibrational load on retaining pile structures, this study examines the influence of predetermined damping hole parameters on the damping effect. It also evaluates the protective efficacy of damping holes on retaining pile structures. Leveraging the foundation pit project at the Julong Avenue Station of Wuhan Metro Line 7 as a reference, on-site blasting construction was monitored to obtain vibration velocities at the top of the retaining pile structure. A numerical calculation model for blasting in the foundation pit was established using LS-DYNA software, and its reliability was verified through the integration of on-site monitoring data at the top of the retaining pile. Multiple damping hole excavation schemes were devised, and their effects on the damping effectiveness were analyzed with respect to various parameters. Safety criteria for the stability of the retaining pile structure were proposed based on the ultimate tensile stress criterion, ultimate shear stress criterion, and Mohr’s criterion. Under the optimized scheme, the dynamic response characteristics of the retaining pile structure were analyzed, and the practical application effects on-site were observed. The research findings indicate that the depth, spacing, and number of damping holes have a significant impact on the damping effect. The safety criterion for the vibrational velocity of the retaining pile structure during blasting is determined to be 26.10 cm/s. Under the optimized scheme, the vibrational velocities at various monitoring points on the retaining pile structure all fall within the safe range, with a maximum reduction rate of 30.9%.
{"title":"Vibration reduction effect of retaining pile structure under the action of damping hole—A case study","authors":"Yingbo Ren, Nan Jiang, Chuan-bo Zhou, Yingkang Yao, Guopeng Lyu","doi":"10.1177/20414196241246285","DOIUrl":"https://doi.org/10.1177/20414196241246285","url":null,"abstract":"In the context of mitigating the impact of blasting-induced seismic waves on excavation processes and reducing the vibrational load on retaining pile structures, this study examines the influence of predetermined damping hole parameters on the damping effect. It also evaluates the protective efficacy of damping holes on retaining pile structures. Leveraging the foundation pit project at the Julong Avenue Station of Wuhan Metro Line 7 as a reference, on-site blasting construction was monitored to obtain vibration velocities at the top of the retaining pile structure. A numerical calculation model for blasting in the foundation pit was established using LS-DYNA software, and its reliability was verified through the integration of on-site monitoring data at the top of the retaining pile. Multiple damping hole excavation schemes were devised, and their effects on the damping effectiveness were analyzed with respect to various parameters. Safety criteria for the stability of the retaining pile structure were proposed based on the ultimate tensile stress criterion, ultimate shear stress criterion, and Mohr’s criterion. Under the optimized scheme, the dynamic response characteristics of the retaining pile structure were analyzed, and the practical application effects on-site were observed. The research findings indicate that the depth, spacing, and number of damping holes have a significant impact on the damping effect. The safety criterion for the vibrational velocity of the retaining pile structure during blasting is determined to be 26.10 cm/s. Under the optimized scheme, the vibrational velocities at various monitoring points on the retaining pile structure all fall within the safe range, with a maximum reduction rate of 30.9%.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140701602","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 : 2024-04-12DOI: 10.1177/20414196241245126
A. Pratomo, Zaka Ruhma, Wawan Rukmono, Martijanti Martijanti, Sutarno Sutarno, K. Tse
A ballistic resistance of hard ceramic combined with aluminum foam sandwich (CAFS) constructions was investigated in this paper. This combination plate is constructed by a front faceplate (FFP), ceramic plates, an aluminum foam (Al-foam) panel, and a rear faceplate (RFP). The material used for the FFP and RFP was heat-treated mild steel with the thicknesses are 5 mm and 3.5 mm, respectively. The ceramic materials to be evaluated are B4C, SiC, and Al2O3. Al-foams were fabricated by varying the stabilizer weight ratio of MgO and Al2O3. The Al-foams have a porosity of 79.93%–82.57%, a pore diameter of 2.51–2.82 mm, the relative density of 0.17–0.24, and plateau stress of 3.88–6.63 MPa. Ballistic tests were carried out only for aluminum foam sandwich (AFS) construction without ceramics to evaluate the manufacturing effect and to obtain a baseline ballistic plate to be improved. Ballistic tests are conducted by using 5.56 × 45 mm bullet with 50 m shooting range and bullet speed of 929–958 m/s. To validate the damage mode and energy absorption capability of the AFS, a numerical model is constructed. The numerical studies were conducted to investigate the damage mode and energy absorption capabilities of each part. The simulation has a good agreement with the experiment result on the damage mode. This model then to be used to study the effect of the additional hard ceramic layer. An interaction between hard ceramic and AFS is also investigated to get a new insight of the energy absorption mechanism during bullet penetration. A new finding shows that ceramic presses the Al-foam to solidify so that it can increase the energy absorbed by the Al-foam. The ceramic is impacted by a bullet pushing the Al-foam so that it undergoes solidification which leads to increasing absorbed energy.
{"title":"Ballistic resistance analysis of hard ceramic combined with aluminum foam sandwich constructions","authors":"A. Pratomo, Zaka Ruhma, Wawan Rukmono, Martijanti Martijanti, Sutarno Sutarno, K. Tse","doi":"10.1177/20414196241245126","DOIUrl":"https://doi.org/10.1177/20414196241245126","url":null,"abstract":"A ballistic resistance of hard ceramic combined with aluminum foam sandwich (CAFS) constructions was investigated in this paper. This combination plate is constructed by a front faceplate (FFP), ceramic plates, an aluminum foam (Al-foam) panel, and a rear faceplate (RFP). The material used for the FFP and RFP was heat-treated mild steel with the thicknesses are 5 mm and 3.5 mm, respectively. The ceramic materials to be evaluated are B4C, SiC, and Al2O3. Al-foams were fabricated by varying the stabilizer weight ratio of MgO and Al2O3. The Al-foams have a porosity of 79.93%–82.57%, a pore diameter of 2.51–2.82 mm, the relative density of 0.17–0.24, and plateau stress of 3.88–6.63 MPa. Ballistic tests were carried out only for aluminum foam sandwich (AFS) construction without ceramics to evaluate the manufacturing effect and to obtain a baseline ballistic plate to be improved. Ballistic tests are conducted by using 5.56 × 45 mm bullet with 50 m shooting range and bullet speed of 929–958 m/s. To validate the damage mode and energy absorption capability of the AFS, a numerical model is constructed. The numerical studies were conducted to investigate the damage mode and energy absorption capabilities of each part. The simulation has a good agreement with the experiment result on the damage mode. This model then to be used to study the effect of the additional hard ceramic layer. An interaction between hard ceramic and AFS is also investigated to get a new insight of the energy absorption mechanism during bullet penetration. A new finding shows that ceramic presses the Al-foam to solidify so that it can increase the energy absorbed by the Al-foam. The ceramic is impacted by a bullet pushing the Al-foam so that it undergoes solidification which leads to increasing absorbed energy.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140709142","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}
Depending on material properties and boundary conditions, various waves propagate within the target, during an impact event. Stress wave attenuation during ballistic impact can be expressed in strain profiles regarding time and distance from the impact point. The design of a ballistic-resistant structure thus depends on the stress wave attenuation. This present study focused on stress wave attenuation under projectile impact in ultra-high performance fibre-reinforced concrete (UHPFRC). 3 mm strain gauges were found suitable for such measurements. Two different types (steel fibres) of UHPFRC (Single fibre (S2): 2 % of 6 mm steel fibre and Hybrid fibre combination (S0.5L1.5): 0.5 % of 6 mm + 1.5 % of 13 mm steel fibres) were used for investigation. During the ballistic impact event, strain profiles at specific distances from the point of impact on both the front and rear surfaces of UHPFRC targets were recorded. The scabbing damage due to tension was captured and analysed in this study through stress wave attenuation. The impact performance of hybrid (Short and Long fibres) S0.5L1.5 UHPFRC combinations was much better than S2 (only short fibres) UHPFRC targets. The hybrid steel fibre UHPFRC also shows higher strain attenuation (than short fibre based UHPFRC) in the range of 10-30 µε/mm. It was concluded that the efficiently designed ballistic-resistant UHPFRC should have higher wave attenuation, implying the concrete has enhanced capacity to absorb and localise energy, thereby mitigating the extent of damage inflicted upon the overall concrete slab.
{"title":"Stress wave attenuation in ultra-high performance fibre-reinforced concrete during ballistic impact","authors":"Nabodyuti Das, Bhaskar Ramagiri, Prakash Nanthagopalan","doi":"10.1177/20414196241246289","DOIUrl":"https://doi.org/10.1177/20414196241246289","url":null,"abstract":"Depending on material properties and boundary conditions, various waves propagate within the target, during an impact event. Stress wave attenuation during ballistic impact can be expressed in strain profiles regarding time and distance from the impact point. The design of a ballistic-resistant structure thus depends on the stress wave attenuation. This present study focused on stress wave attenuation under projectile impact in ultra-high performance fibre-reinforced concrete (UHPFRC). 3 mm strain gauges were found suitable for such measurements. Two different types (steel fibres) of UHPFRC (Single fibre (S2): 2 % of 6 mm steel fibre and Hybrid fibre combination (S0.5L1.5): 0.5 % of 6 mm + 1.5 % of 13 mm steel fibres) were used for investigation. During the ballistic impact event, strain profiles at specific distances from the point of impact on both the front and rear surfaces of UHPFRC targets were recorded. The scabbing damage due to tension was captured and analysed in this study through stress wave attenuation. The impact performance of hybrid (Short and Long fibres) S0.5L1.5 UHPFRC combinations was much better than S2 (only short fibres) UHPFRC targets. The hybrid steel fibre UHPFRC also shows higher strain attenuation (than short fibre based UHPFRC) in the range of 10-30 µε/mm. It was concluded that the efficiently designed ballistic-resistant UHPFRC should have higher wave attenuation, implying the concrete has enhanced capacity to absorb and localise energy, thereby mitigating the extent of damage inflicted upon the overall concrete slab.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140728795","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 : 2024-04-08DOI: 10.1177/20414196241245124
T. Horiguchi, Yuta Miyahara, Yoshiharu Komatsu
Recently, the magnitude of landslide caused by torrential rain and typhoons is increasing in Japan. This high intensity rainfall disaster induces some structural failure of steel pipe open Sabo dams. Thus, current static design loads and impact loads are being considered. To prevent some structural failure of the dam, a new design concept is necessary at the severe load that is exceeding the present design load. However, the influence of debris flow impact load on steel pipe open Sabo dam is not clear to make a design load. The study experimentally approaches a vertical load distribution shape and its time history based on a comparison with a wedge approach shape and a front boulder concentrated shape. The load and moment action of a front boulder concentrated shape debris flow is greater than that of a wedge approach shape. Mechanism making the difference is made clear by observation of vertical detail measurement of impact load.
{"title":"Influence of approach shape of debris flow on impact load to open Sabo dam in experiment","authors":"T. Horiguchi, Yuta Miyahara, Yoshiharu Komatsu","doi":"10.1177/20414196241245124","DOIUrl":"https://doi.org/10.1177/20414196241245124","url":null,"abstract":"Recently, the magnitude of landslide caused by torrential rain and typhoons is increasing in Japan. This high intensity rainfall disaster induces some structural failure of steel pipe open Sabo dams. Thus, current static design loads and impact loads are being considered. To prevent some structural failure of the dam, a new design concept is necessary at the severe load that is exceeding the present design load. However, the influence of debris flow impact load on steel pipe open Sabo dam is not clear to make a design load. The study experimentally approaches a vertical load distribution shape and its time history based on a comparison with a wedge approach shape and a front boulder concentrated shape. The load and moment action of a front boulder concentrated shape debris flow is greater than that of a wedge approach shape. Mechanism making the difference is made clear by observation of vertical detail measurement of impact load.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140731292","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 : 2024-04-02DOI: 10.1177/20414196241245125
Ravi Mudragada, Pradeep Bhargava
The occurrence of direct shear failure in structural members during the early phases of blast loading prior to the development of appreciable curvature can lead to sudden and catastrophic consequences for protected facilities exposed to near-field and/or close-in blasts. Thus, accurately predicting direct shear failure in structural members subjected to blast loads is crucial. Consequently, this paper presents a novel 3-D finite element (FE)-based cohesive interface modeling approach capable of capturing the shear slip near the supports and accurately predicting direct shear failure in blast-loaded reinforced concrete (RC) members. The validity of the proposed numerical model is established with experimental data. Three distinct blast load cases varying from distant to close-in are applied to verify the applicability and highlight the novelty of the proposed model. Results show that direct shear failure is inherently captured within the modeling framework of the proposed cohesive interface models, eliminating the need for externally adopted damage criteria seen in existing 3-D FE-based continuum models. Further, the effectiveness of the cohesive interface model in the accurate blast damage assessment of structural members is manifested by using pressure-impulse (P-I) diagrams.
在爆炸荷载的早期阶段，结构构件在出现明显曲率之前发生直接剪切破坏，可能会对暴露在近场和/或近距离爆炸中的受保护设施造成突然的灾难性后果。因此，准确预测结构构件在爆炸荷载作用下的直接剪切破坏至关重要。因此，本文提出了一种新颖的基于三维有限元（FE）的内聚界面建模方法，该方法能够捕捉支撑附近的剪切滑移，并准确预测受爆炸荷载的钢筋混凝土（RC）构件的直接剪切破坏。实验数据证明了所建议的数值模型的有效性。应用了从远处到近处的三种不同的爆炸荷载情况，以验证所提模型的适用性并突出其新颖性。结果表明，在所提出的内聚界面模型的建模框架内可以捕捉到直接的剪切破坏，无需在现有的基于 3-D FE 的连续模型中采用外部破坏标准。此外，内聚界面模型在准确评估结构部件爆炸破坏方面的有效性还体现在压力-冲量（P-I）图上。
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