Pub Date : 2023-06-01DOI: 10.1177/20414196231177364
Adam A Dennis, S. Rigby
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.
{"title":"The Direction-encoded Neural Network: A machine learning approach to rapidly predict blast loading in obstructed environments","authors":"Adam A Dennis, S. Rigby","doi":"10.1177/20414196231177364","DOIUrl":"https://doi.org/10.1177/20414196231177364","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43798769","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 : 2023-05-19DOI: 10.1177/20414196231177358
J. Liu, C. Gao, Z. Sun, JW Yin
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 [Formula: see text] and that of scaled distance is [Formula: see text]. 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.
{"title":"On the estimation of near-field air blast peak overpressure from cylindrical charges","authors":"J. Liu, C. Gao, Z. Sun, JW Yin","doi":"10.1177/20414196231177358","DOIUrl":"https://doi.org/10.1177/20414196231177358","url":null,"abstract":"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 [Formula: see text] and that of scaled distance is [Formula: see text]. 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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"227 11","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41258803","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 : 2023-05-11DOI: 10.1177/20414196231174916
Kirtika Samanta, P. Maheshwari
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.
{"title":"Elasto-plastic analysis of foundations during emergency shutdown due to blast loading","authors":"Kirtika Samanta, P. Maheshwari","doi":"10.1177/20414196231174916","DOIUrl":"https://doi.org/10.1177/20414196231174916","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48759884","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 : 2023-04-04DOI: 10.1177/20414196231167596
Ayham Ali Salamy, I. Hammoud
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.
{"title":"Simulation of blast-induced rock tunnel damage using a 3D numerical model","authors":"Ayham Ali Salamy, I. Hammoud","doi":"10.1177/20414196231167596","DOIUrl":"https://doi.org/10.1177/20414196231167596","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42169917","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 : 2023-03-29DOI: 10.1177/20414196231166067
C. Hung, Ying-Kuan Tsai, Li-Kai Chien, S. Pi
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.
{"title":"Numerical study of a near-field explosion using arbitrary Lagrangian–Eulerian mapping technique","authors":"C. Hung, Ying-Kuan Tsai, Li-Kai Chien, S. Pi","doi":"10.1177/20414196231166067","DOIUrl":"https://doi.org/10.1177/20414196231166067","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42722098","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 : 2023-03-24DOI: 10.1177/20414196231164431
A. Antoniou, T. Børvik, M. Kristoffersen
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.
{"title":"Evaluation of automatic versus material test-based calibrations of concrete models for ballistic impact simulations","authors":"A. Antoniou, T. Børvik, M. Kristoffersen","doi":"10.1177/20414196231164431","DOIUrl":"https://doi.org/10.1177/20414196231164431","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49053648","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 : 2023-03-17DOI: 10.1177/20414196231164432
S. Anas, M. Shariq, Meraj Alam, M. Umair
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 explo
{"title":"Modeling of crashworthy foam mounted braced unreinforced brick masonry wall and prediction of anti-blast performance","authors":"S. Anas, M. Shariq, Meraj Alam, M. Umair","doi":"10.1177/20414196231164432","DOIUrl":"https://doi.org/10.1177/20414196231164432","url":null,"abstract":"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 explo","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47175082","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 : 2023-02-28DOI: 10.1177/20414196231160235
R. Perkins, C. Duncan, Daniel Johnson, T. Stone, J. Sherburn, M. Chandler, Robert Moser, B. Paliwal, R. Prabhu, Y. Hammi
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.
{"title":"Assessment of the ballistic impact response of Cor-Tuf UHPC concrete using the HJC constitutive model","authors":"R. Perkins, C. Duncan, Daniel Johnson, T. Stone, J. Sherburn, M. Chandler, Robert Moser, B. Paliwal, R. Prabhu, Y. Hammi","doi":"10.1177/20414196231160235","DOIUrl":"https://doi.org/10.1177/20414196231160235","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45101345","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 : 2023-02-08DOI: 10.1177/20414196231155947
Mohammad Mohsin Khan, M. Iqbal
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.
{"title":"Design, development, and calibration of split Hopkinson pressure bar system for Dynamic material characterization of concrete","authors":"Mohammad Mohsin Khan, M. Iqbal","doi":"10.1177/20414196231155947","DOIUrl":"https://doi.org/10.1177/20414196231155947","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41781059","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 : 2023-01-09DOI: 10.1177/20414196221150661
Bowen Zhao, N. Jiang, Chuan-bo Zhou, Yingkang Yao, Wenbin Zhou, Zhongwei Cai
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.
{"title":"Safety assessment for a ballast railway induced by underground subway tunnel blasting: A case study","authors":"Bowen Zhao, N. Jiang, Chuan-bo Zhou, Yingkang Yao, Wenbin Zhou, Zhongwei Cai","doi":"10.1177/20414196221150661","DOIUrl":"https://doi.org/10.1177/20414196221150661","url":null,"abstract":"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.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48929683","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}
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