Pub Date : 2022-03-26DOI: 10.1177/20414196221075821
Chanel Fallon, G. McShane
Elastomer coatings have been found to offer protection to structural components when subjected to dynamic load cases, such as impact and blast. One such application of interest is the protection of concrete structures. Elastomer coatings have the potential to provide a cost effective and practical protective solution. The dynamic response of quasi-brittle concrete structures to blast loading is complex, with a range of dynamic response regimes. It remains to be identified in which regimes of response an elastomer coating can offer a protective benefit. Numerical and analytical modelling of thin, one-way reinforced concrete slabs subjected to varying intensities of simulated blast loading is carried out, in order to ascertain the protective effect of an elastomeric coating. Three configurations are considered: uncoated, coated with elastomer on the blast-receiving face and coated with elastomer on the non-blast-receiving face. It is found that the slab is relatively insensitive to the elastomer coating during response regimes where concrete damage is minimal. At higher load intensities, where the slab exhibits severe damage, the numerical results indicate a substantial reduction in slab deflections may be achieved by coating on the non-blast-receiving face. At the highest loading intensities, a shift in failure mechanism is observed to one dominated by transverse shear at the supports. An analytical model quantitatively predicts a substantial coating benefit in protecting against this failure mechanism.
{"title":"Modelling the response regimes of elastomer-coated concrete slabs subjected to blast pressure loading","authors":"Chanel Fallon, G. McShane","doi":"10.1177/20414196221075821","DOIUrl":"https://doi.org/10.1177/20414196221075821","url":null,"abstract":"Elastomer coatings have been found to offer protection to structural components when subjected to dynamic load cases, such as impact and blast. One such application of interest is the protection of concrete structures. Elastomer coatings have the potential to provide a cost effective and practical protective solution. The dynamic response of quasi-brittle concrete structures to blast loading is complex, with a range of dynamic response regimes. It remains to be identified in which regimes of response an elastomer coating can offer a protective benefit. Numerical and analytical modelling of thin, one-way reinforced concrete slabs subjected to varying intensities of simulated blast loading is carried out, in order to ascertain the protective effect of an elastomeric coating. Three configurations are considered: uncoated, coated with elastomer on the blast-receiving face and coated with elastomer on the non-blast-receiving face. It is found that the slab is relatively insensitive to the elastomer coating during response regimes where concrete damage is minimal. At higher load intensities, where the slab exhibits severe damage, the numerical results indicate a substantial reduction in slab deflections may be achieved by coating on the non-blast-receiving face. At the highest loading intensities, a shift in failure mechanism is observed to one dominated by transverse shear at the supports. An analytical model quantitatively predicts a substantial coating benefit in protecting against this failure mechanism.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"14 1","pages":"3 - 27"},"PeriodicalIF":2.0,"publicationDate":"2022-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41425103","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 : 2022-03-18DOI: 10.1177/20414196211062620
Zihong Gan, Y. Zhuge, D. Thambiratnam, Tommy H. T. Chan, T. Zahra, Mohammad Asad
Auxetic materials, possessing negative Poisson’s ratios (NPRs), have the ability to shrink (or expand) in the lateral direction under an axial compressive (or tensile) force respectively. Due to this unique feature, an auxetic material is found to sustain high energy absorption capacity, fracture toughness and shear resistance and thus regarded as one of the future materials in the field of impact protection. However, civil engineering applications of auxetic structures or materials are minimal due to miscellaneous restrictions on NPR effects. Accumulative developments in auxetics have facilitated their applications in cementitious materials in recent years. This paper presents an overview of recent advances in the development of auxetic cementitious composites and analyses and summarises their mechanical properties under different loading conditions. Prior to extensive finite element simulations, more attention has been given to the limited experimental results. Particular attention is paid to the expansionary feasibility of the parent material to introduce auxetic behaviour, with precise identification of the limitations, innovative composition methods and facilitation of auxetic features. Finally, the paper outlines the limitations of the current research and envisages few future research opportunities in auxetic cementitious composites.
{"title":"Recent advances in auxetics: Applications in cementitious composites","authors":"Zihong Gan, Y. Zhuge, D. Thambiratnam, Tommy H. T. Chan, T. Zahra, Mohammad Asad","doi":"10.1177/20414196211062620","DOIUrl":"https://doi.org/10.1177/20414196211062620","url":null,"abstract":"Auxetic materials, possessing negative Poisson’s ratios (NPRs), have the ability to shrink (or expand) in the lateral direction under an axial compressive (or tensile) force respectively. Due to this unique feature, an auxetic material is found to sustain high energy absorption capacity, fracture toughness and shear resistance and thus regarded as one of the future materials in the field of impact protection. However, civil engineering applications of auxetic structures or materials are minimal due to miscellaneous restrictions on NPR effects. Accumulative developments in auxetics have facilitated their applications in cementitious materials in recent years. This paper presents an overview of recent advances in the development of auxetic cementitious composites and analyses and summarises their mechanical properties under different loading conditions. Prior to extensive finite element simulations, more attention has been given to the limited experimental results. Particular attention is paid to the expansionary feasibility of the parent material to introduce auxetic behaviour, with precise identification of the limitations, innovative composition methods and facilitation of auxetic features. Finally, the paper outlines the limitations of the current research and envisages few future research opportunities in auxetic cementitious composites.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"13 1","pages":"295 - 316"},"PeriodicalIF":2.0,"publicationDate":"2022-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45273779","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 : 2022-03-03DOI: 10.1177/20414196211073502
Mohammad Asad, T. Zahra, D. Thambiratnam, Tommy H. T. Chan, Xue-mei Liu, Y. Zhuge, M. Hayne, Anthony Morris, Christina Nguyen
This paper summarises the development of a state-of-art impact testing machine for simulating impacts such as vehicular crashes or debris impacts onto structures. The machine has a 200 kg pneumatically powered projectile which can travel horizontally within the barrel of the machine with a maximum velocity of 50 m/s to impact the target structure. The maximum kinetic energy that can be generated by the projectile is 125 kJ by using different combinations of mass and velocity. The diameter of the projectile is 214 mm, and its impacting face can be changed to different shapes, such as flat circle, flat square or an elliptical nose to suit different impact scenarios. An innovative braking mechanism incorporating a crush tube is attached within the barrel to ensure safety when the projectile fails to be restrained by the impact. The crush tube can absorb the maximum imparted by the moving projectile. An advanced data acquisition system is installed to collect quantitative and qualitative test data during a period of 50 ms to 1 s. Two high-speed digital image correlation (DIC) cameras are attached and synchronised with the operation of the impact testing machine to record the images at the rate of 50,000 frames per second. Outputs in terms of strains, deformations, accelerations of the target structure with a record of damage history can be analysed using this 3D DIC technique. The paper also briefly presents the first application of this machine for impact testing masonry wall structures.
{"title":"Innovative impact testing machine for enhancing impact related research in Australia","authors":"Mohammad Asad, T. Zahra, D. Thambiratnam, Tommy H. T. Chan, Xue-mei Liu, Y. Zhuge, M. Hayne, Anthony Morris, Christina Nguyen","doi":"10.1177/20414196211073502","DOIUrl":"https://doi.org/10.1177/20414196211073502","url":null,"abstract":"This paper summarises the development of a state-of-art impact testing machine for simulating impacts such as vehicular crashes or debris impacts onto structures. The machine has a 200 kg pneumatically powered projectile which can travel horizontally within the barrel of the machine with a maximum velocity of 50 m/s to impact the target structure. The maximum kinetic energy that can be generated by the projectile is 125 kJ by using different combinations of mass and velocity. The diameter of the projectile is 214 mm, and its impacting face can be changed to different shapes, such as flat circle, flat square or an elliptical nose to suit different impact scenarios. An innovative braking mechanism incorporating a crush tube is attached within the barrel to ensure safety when the projectile fails to be restrained by the impact. The crush tube can absorb the maximum imparted by the moving projectile. An advanced data acquisition system is installed to collect quantitative and qualitative test data during a period of 50 ms to 1 s. Two high-speed digital image correlation (DIC) cameras are attached and synchronised with the operation of the impact testing machine to record the images at the rate of 50,000 frames per second. Outputs in terms of strains, deformations, accelerations of the target structure with a record of damage history can be analysed using this 3D DIC technique. The paper also briefly presents the first application of this machine for impact testing masonry wall structures.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"13 1","pages":"273 - 294"},"PeriodicalIF":2.0,"publicationDate":"2022-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45038968","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 : 2022-02-21DOI: 10.1177/20414196211069573
N. Kishi, M. Komuro, K. Kono, Tomoki Kawarai
Ultrahigh-performance fiber-reinforced concrete (UHPFRC) is an advanced cement-based composite material. Its ultrahigh compressive strength and high ductility can enable the downsizing of structural members, with special application to high-rise buildings. These excellent mechanical properties also allow its application in protective structures to resist high-speed penetration, low-velocity impact, and blast loading. UHPFRC with a compressive strength of approximately 150–200 MPa has traditionally been used to investigate the impact resistance of structural members under low-velocity impact loading. Recently, however, porosity-free concrete of the 400 MPa class of compressive strength has been developed. In this paper, to investigate the effects of the concrete strength and the steel fiber volume fraction on the impact resistance of porosity-free fiber-reinforced concrete (PFFRC) members, static and drop-weight impact loading tests were conducted on PFFRC beams by varying the volume fraction of steel fiber from 1 to 3.5%. As reference beams, 90 MPa high-strength fiber-reinforced concrete (HSFRC) beams with a 2% fiber volume fraction and normal-strength concrete (NSC) beams without stirrups and steel fibers were also tested. The results obtained from this study were as follows: (1) the static load-carrying capacity of a PFFRC beam can be enhanced by more than two and three times that of an NSC beam by adding 1 and 3.5% volume fractions of steel fiber, respectively; (2) a PFFRC beam with 3.5% fiber had the greatest impact resistance of all the beams considered in this study, and the beam with 2% fiber volume had the second-greatest performance, but the difference was small; (3) even though an HSFRC beam with 2% fiber had a smaller static load-carrying capacity than a PFFRC beam with 1% fiber, the former exhibited a slightly greater impact resistance than the latter because the bridging effect of the steel fibers has a greater influence under impact loading than under static loading.
{"title":"Impact resistance of porosity-free fiber-reinforced concrete (PFFRC) beams under low-velocity impact loading","authors":"N. Kishi, M. Komuro, K. Kono, Tomoki Kawarai","doi":"10.1177/20414196211069573","DOIUrl":"https://doi.org/10.1177/20414196211069573","url":null,"abstract":"Ultrahigh-performance fiber-reinforced concrete (UHPFRC) is an advanced cement-based composite material. Its ultrahigh compressive strength and high ductility can enable the downsizing of structural members, with special application to high-rise buildings. These excellent mechanical properties also allow its application in protective structures to resist high-speed penetration, low-velocity impact, and blast loading. UHPFRC with a compressive strength of approximately 150–200 MPa has traditionally been used to investigate the impact resistance of structural members under low-velocity impact loading. Recently, however, porosity-free concrete of the 400 MPa class of compressive strength has been developed. In this paper, to investigate the effects of the concrete strength and the steel fiber volume fraction on the impact resistance of porosity-free fiber-reinforced concrete (PFFRC) members, static and drop-weight impact loading tests were conducted on PFFRC beams by varying the volume fraction of steel fiber from 1 to 3.5%. As reference beams, 90 MPa high-strength fiber-reinforced concrete (HSFRC) beams with a 2% fiber volume fraction and normal-strength concrete (NSC) beams without stirrups and steel fibers were also tested. The results obtained from this study were as follows: (1) the static load-carrying capacity of a PFFRC beam can be enhanced by more than two and three times that of an NSC beam by adding 1 and 3.5% volume fractions of steel fiber, respectively; (2) a PFFRC beam with 3.5% fiber had the greatest impact resistance of all the beams considered in this study, and the beam with 2% fiber volume had the second-greatest performance, but the difference was small; (3) even though an HSFRC beam with 2% fiber had a smaller static load-carrying capacity than a PFFRC beam with 1% fiber, the former exhibited a slightly greater impact resistance than the latter because the bridging effect of the steel fibers has a greater influence under impact loading than under static loading.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"13 1","pages":"344 - 362"},"PeriodicalIF":2.0,"publicationDate":"2022-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48355008","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 : 2022-02-10DOI: 10.1177/20414196211069574
A. Remennikov, Dulara Madupushpa Kalubadanage, Xiaohan Yang, T. Ren
As mining progresses into deep ore deposits in Australia, geo-hazards such as coal burst and outbursts are becoming a major concern for mine workers. The occurrence of geo-hazards involved the ejection of coal lumps and sometimes large volumes of hazardous gases such as methane and carbon dioxide. Whilst it is extremely important to de-stress and de-gas the seam and adjacent strata before roadway development and install competent support systems such as steel mesh and bolt, the last line of protection will be the installation of a protective canopy on the Continuous Miner (CM), which is typically used for roadway developments, to shield mine workers from these deadly dynamic impacts of coal and rock resulting from a burst or outburst. This paper aims to introduce the design, manufacture and testing of an innovative modular protective structure on the CM in underground coal mines. The developed protective system can be easily assembled in the underground mining environment and provide a high level of protection against flying debris hazards in the event of a coal burst. The extensive experimental program and numerical simulations have confirmed the high performance of the protective system against high-speed impact loading by single and multiple coal rocks and projectiles.
{"title":"The development of specialised modular protective structure on continuous miners against coal burst hazards","authors":"A. Remennikov, Dulara Madupushpa Kalubadanage, Xiaohan Yang, T. Ren","doi":"10.1177/20414196211069574","DOIUrl":"https://doi.org/10.1177/20414196211069574","url":null,"abstract":"As mining progresses into deep ore deposits in Australia, geo-hazards such as coal burst and outbursts are becoming a major concern for mine workers. The occurrence of geo-hazards involved the ejection of coal lumps and sometimes large volumes of hazardous gases such as methane and carbon dioxide. Whilst it is extremely important to de-stress and de-gas the seam and adjacent strata before roadway development and install competent support systems such as steel mesh and bolt, the last line of protection will be the installation of a protective canopy on the Continuous Miner (CM), which is typically used for roadway developments, to shield mine workers from these deadly dynamic impacts of coal and rock resulting from a burst or outburst. This paper aims to introduce the design, manufacture and testing of an innovative modular protective structure on the CM in underground coal mines. The developed protective system can be easily assembled in the underground mining environment and provide a high level of protection against flying debris hazards in the event of a coal burst. The extensive experimental program and numerical simulations have confirmed the high performance of the protective system against high-speed impact loading by single and multiple coal rocks and projectiles.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"13 1","pages":"182 - 208"},"PeriodicalIF":2.0,"publicationDate":"2022-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48369998","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}
J. Denny, G. Langdon, S. Rigby, A. Dickinson, James Batchelor, Lawrence Surey
Explosions increasingly occur in densely populated, urban locations. Primary blast injuries (PBIs), caused by exposure to blast wave overpressure, can be predicted using injury criteria, although many are based on idealised loading scenarios that do not necessarily reflect real life situations. At present, there is limited understanding of how, and to what extent, blast-structure interaction influences injury risk, and the suitability of injury criteria that assume idealised loading. This work employed computational fluid dynamics to investigate the influence of blast interaction effects such as shielding and channelling on blast load characteristics and predicted PBIs. The validated modelling showed that blast interaction with common urban features like walls and corners resulted in complex waveforms featuring multiple peaks and less clearly defined durations, and that these alter potential injury risk maps. For example, blast shielding due to corners reduced peak overpressures by 43%–60% at locations behind the corner. However, when the urban layout included a corner and a wall structure, higher pressures and impulse due to channelling were observed. The channelling significantly increased the injury risk at the exposed location and reduced the shielding effects behind the corner. In these cases, the application and interpretation of existing injury criteria had several limitations and reduced reliability. This demonstrates that structural-blast interaction from common urban layouts has a significant effect on PBI risk. Specific challenges and further work to develop understanding and reliability of injury prediction for urban blast scenarios are discussed.
{"title":"A numerical investigation of blast-structure interaction effects on primary blast injury risk and the suitability of existing injury prediction methods","authors":"J. Denny, G. Langdon, S. Rigby, A. Dickinson, James Batchelor, Lawrence Surey","doi":"10.31224/2112","DOIUrl":"https://doi.org/10.31224/2112","url":null,"abstract":"Explosions increasingly occur in densely populated, urban locations. Primary blast injuries (PBIs), caused by exposure to blast wave overpressure, can be predicted using injury criteria, although many are based on idealised loading scenarios that do not necessarily reflect real life situations. At present, there is limited understanding of how, and to what extent, blast-structure interaction influences injury risk, and the suitability of injury criteria that assume idealised loading. This work employed computational fluid dynamics to investigate the influence of blast interaction effects such as shielding and channelling on blast load characteristics and predicted PBIs. The validated modelling showed that blast interaction with common urban features like walls and corners resulted in complex waveforms featuring multiple peaks and less clearly defined durations, and that these alter potential injury risk maps. For example, blast shielding due to corners reduced peak overpressures by 43%–60% at locations behind the corner. However, when the urban layout included a corner and a wall structure, higher pressures and impulse due to channelling were observed. The channelling significantly increased the injury risk at the exposed location and reduced the shielding effects behind the corner. In these cases, the application and interpretation of existing injury criteria had several limitations and reduced reliability. This demonstrates that structural-blast interaction from common urban layouts has a significant effect on PBI risk. Specific challenges and further work to develop understanding and reliability of injury prediction for urban blast scenarios are discussed.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47847126","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 : 2022-01-15DOI: 10.1177/20414196211065477
T. Bui, Dhafar Al Galib, A. Bennani, A. Limam
The collapse of tubes under axial load is an important subject from the safety point of view, particularly in the design of energy absorbing devices used in many engineering applications. In this study, quasi-static and dynamic experiments were carried out on square thin-walled aluminum extrusions to investigate the effects of circular holes. Cutouts were introduced in the four corners of the square-section tube, not far from the end boundary of the tube, in order both to decrease the first peak load on the load-displacement characteristic and to control the collapse mode. Different aspects, such as the buckling modes and the energy absorption in quasi-static axial crushing tests, as well as dynamic effects and material rheology contributions in dynamic crushing tests, have been examined. For the dynamic tests, the parameters were the impacting mass and its velocity. The results showed a drop in the first peak function of the openings’ radius and the tube’s energy absorption capacity was kept. A comparison between static and dynamic tests results was carried out and the interpretation of the results in terms of deformation mechanism and energy absorption was discussed. Numerical simulations with the finite element code ABAQUS were conducted to confirm the experimental findings. The results of different numerical models, implicit and explicit calculations, that contribute to a basic understanding of the buckling and prediction of the crash behavior of the aluminum components without and with the cutouts are presented.
{"title":"Experimental and numerical study on static and dynamic axial crushing of square aluminum tubes: Effects of cutouts","authors":"T. Bui, Dhafar Al Galib, A. Bennani, A. Limam","doi":"10.1177/20414196211065477","DOIUrl":"https://doi.org/10.1177/20414196211065477","url":null,"abstract":"The collapse of tubes under axial load is an important subject from the safety point of view, particularly in the design of energy absorbing devices used in many engineering applications. In this study, quasi-static and dynamic experiments were carried out on square thin-walled aluminum extrusions to investigate the effects of circular holes. Cutouts were introduced in the four corners of the square-section tube, not far from the end boundary of the tube, in order both to decrease the first peak load on the load-displacement characteristic and to control the collapse mode. Different aspects, such as the buckling modes and the energy absorption in quasi-static axial crushing tests, as well as dynamic effects and material rheology contributions in dynamic crushing tests, have been examined. For the dynamic tests, the parameters were the impacting mass and its velocity. The results showed a drop in the first peak function of the openings’ radius and the tube’s energy absorption capacity was kept. A comparison between static and dynamic tests results was carried out and the interpretation of the results in terms of deformation mechanism and energy absorption was discussed. Numerical simulations with the finite element code ABAQUS were conducted to confirm the experimental findings. The results of different numerical models, implicit and explicit calculations, that contribute to a basic understanding of the buckling and prediction of the crash behavior of the aluminum components without and with the cutouts are presented.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"13 1","pages":"403 - 438"},"PeriodicalIF":2.0,"publicationDate":"2022-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49541660","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 : 2022-01-06DOI: 10.1177/20414196211065480
Yong Zhang, Li Chen, Dongbao Zhou
In this study, the dynamic mechanical properties of hybrid fiber reinforced concrete (HFRC) are analyzed with respect to failure mode, dynamic increase factor (DIF), and peak strain by means of a SHPB testing apparatus. The factors that influence the dynamic mechanical properties include fiber type and fiber content. It is concluded that the best dynamic mechanical properties of fibers are CS-PHFRC at medium and low strain rates and AS-PHFRC at a high strain rate. Within a certain range, the higher the fiber content is, the larger the DIF of the corresponding HFRC and the more obvious the increase in dynamic compressive strength. AS-CSHFRC improves the dynamic compressive deformability of the HFRC. The polypropylene fiber causes plasticity, as shown in the failure mode of concrete. The Ottosen nonlinear elastic model, modified by introducing the damage factor, can better describe the dynamic mechanical properties of HFRC.
{"title":"Dynamic mechanical properties of hybrid fiber reinforced concrete","authors":"Yong Zhang, Li Chen, Dongbao Zhou","doi":"10.1177/20414196211065480","DOIUrl":"https://doi.org/10.1177/20414196211065480","url":null,"abstract":"In this study, the dynamic mechanical properties of hybrid fiber reinforced concrete (HFRC) are analyzed with respect to failure mode, dynamic increase factor (DIF), and peak strain by means of a SHPB testing apparatus. The factors that influence the dynamic mechanical properties include fiber type and fiber content. It is concluded that the best dynamic mechanical properties of fibers are CS-PHFRC at medium and low strain rates and AS-PHFRC at a high strain rate. Within a certain range, the higher the fiber content is, the larger the DIF of the corresponding HFRC and the more obvious the increase in dynamic compressive strength. AS-CSHFRC improves the dynamic compressive deformability of the HFRC. The polypropylene fiber causes plasticity, as shown in the failure mode of concrete. The Ottosen nonlinear elastic model, modified by introducing the damage factor, can better describe the dynamic mechanical properties of HFRC.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"13 1","pages":"579 - 598"},"PeriodicalIF":2.0,"publicationDate":"2022-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44839098","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 : 2021-12-29DOI: 10.1177/20414196211059201
K. Fischer, Jan Dirk van der Woerd, W. Harwick, A. Stolz
Blast loading scenarios and the corresponding hazards have to be evaluated for infrastructure elements and buildings especially at industrial sites for safety and security issues. Point fixed corrugated metal sheets are often applied as façade elements and can become a hazard for humans if they are pulled off. This paper investigates the dynamic bearing capacity of such structural members in terms of their general bending behavior in the middle of the span and pull-out behaviors at the fixing points. The elements are fixed at two sides and the load transfer is uniaxial. An experimental series with static and dynamic tests forms the basis to identify the predominant failure modes and to quantify the maximum stress values that can be absorbed until the investigated structural members fail. The experimental findings are applied to create and to optimize an engineering model for the fast and effective assessment of the structural response. The aim is the derivation of a validated model which is capable to predict the blast loading behavior of metal sheets including arbitrary dimensions, material properties, and screw connections. Results of this study can be integrated into a systematic risk and resilience management process to assess expected damage effects and the evaluation of robustness.
{"title":"Dynamic bearing capacity of point fixed corrugated metal profile sheets subjected to blast loading","authors":"K. Fischer, Jan Dirk van der Woerd, W. Harwick, A. Stolz","doi":"10.1177/20414196211059201","DOIUrl":"https://doi.org/10.1177/20414196211059201","url":null,"abstract":"Blast loading scenarios and the corresponding hazards have to be evaluated for infrastructure elements and buildings especially at industrial sites for safety and security issues. Point fixed corrugated metal sheets are often applied as façade elements and can become a hazard for humans if they are pulled off. This paper investigates the dynamic bearing capacity of such structural members in terms of their general bending behavior in the middle of the span and pull-out behaviors at the fixing points. The elements are fixed at two sides and the load transfer is uniaxial. An experimental series with static and dynamic tests forms the basis to identify the predominant failure modes and to quantify the maximum stress values that can be absorbed until the investigated structural members fail. The experimental findings are applied to create and to optimize an engineering model for the fast and effective assessment of the structural response. The aim is the derivation of a validated model which is capable to predict the blast loading behavior of metal sheets including arbitrary dimensions, material properties, and screw connections. Results of this study can be integrated into a systematic risk and resilience management process to assess expected damage effects and the evaluation of robustness.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"13 1","pages":"487 - 508"},"PeriodicalIF":2.0,"publicationDate":"2021-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46926057","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 : 2021-12-27DOI: 10.1177/20414196211059552
Hiroshi Kokuryo, T. Horiguchi, N. Ishikawa
Recently, steel pipe open type protective structures (steel open dams) have been damaged because of large-scale debris flow resulting from torrential rainfall based on abnormal climate. This article proposes a safety assessment method for the load-carrying capacity of a steel open dam against large-scale debris flow load (level II load) using the energy constant law. First, the safety assessment method of steel open dams is proposed that the ultimate strength must be larger than the required strength against the level II load, which is determined by using the energy constant law. Second, the load-carrying capacities of three types of steel open dams with different structural shapes against the front and eccentric debris flow loadings are investigated by a push-over analysis. Finally, the safety assessments on load-carrying capacities against the front and eccentric debris flow loading are confirmed and the strength reduction by the eccentric loading is examined for three steel open dams.
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