Pub Date : 2022-09-07DOI: 10.1177/20414196221120512
M. Sherif, H. Othman, H. Marzouk, H. Aoude
This paper presents a new material constitutive model for simulating the uniaxial material behavior of ultra-high performance fiber reinforced concrete (UHP-FRC). The model accounts for the contribution of the steel fiber content to the tensile behavior. The model variables are the fracture energy, the characteristic length, and the crack bandwidth. Thus, it guarantees a mesh size independent numerical modeling of UHP-FRC. The model is developed based on the reported results of a state-of-the-art and highly accurate experimental investigation for the uniaxial behavior of UHP-FRC. This paper also adopts the concrete damage plasticity model (CDP) as a multi-axial yield surface criterion and presents the applicability of the material constitutive model and CDP for modeling UHP-FRC under unconfined non-contact blast loading. The results of the numerical models are validated against the experimental data of shock tube testing conducted by the authors at the University of Ottawa shock tube in collaboration with Ryerson University. The results revealed that the developed material constitutive model accurately represented the uniaxial behavior of UHP-FRC. The CDP model combined with the material constitutive model developed in this study can accurately model UHP-FRC structures under unconfined non-contact blast loading.
{"title":"An experimentally validated numerical analysis of UHP-FRC subjected to blast loading","authors":"M. Sherif, H. Othman, H. Marzouk, H. Aoude","doi":"10.1177/20414196221120512","DOIUrl":"https://doi.org/10.1177/20414196221120512","url":null,"abstract":"This paper presents a new material constitutive model for simulating the uniaxial material behavior of ultra-high performance fiber reinforced concrete (UHP-FRC). The model accounts for the contribution of the steel fiber content to the tensile behavior. The model variables are the fracture energy, the characteristic length, and the crack bandwidth. Thus, it guarantees a mesh size independent numerical modeling of UHP-FRC. The model is developed based on the reported results of a state-of-the-art and highly accurate experimental investigation for the uniaxial behavior of UHP-FRC. This paper also adopts the concrete damage plasticity model (CDP) as a multi-axial yield surface criterion and presents the applicability of the material constitutive model and CDP for modeling UHP-FRC under unconfined non-contact blast loading. The results of the numerical models are validated against the experimental data of shock tube testing conducted by the authors at the University of Ottawa shock tube in collaboration with Ryerson University. The results revealed that the developed material constitutive model accurately represented the uniaxial behavior of UHP-FRC. The CDP model combined with the material constitutive model developed in this study can accurately model UHP-FRC structures under unconfined non-contact blast loading.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43851831","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 : 2022-09-02DOI: 10.1177/20414196221115869
Omar Ghareeb Alshammari, Obed Samuelraj Isaac, S. Clarke, S. Rigby
Obstructing the passage of blast waves is an effective method of mitigating blast pressures downstream of the obstacle. To this end, the interaction between a blast wave and a simplified structural shape, such as a cylinder, has been widely investigated to understand the complex flow pattern that ensues around the obstacle. The patterns include the interference zones of the incident wave, the diffracted wave, and other secondary waves in the downstream region. Such zones are responsible for causing significant modifications to the blast wave parameters. This research aims to identify and study the factors that serve to mitigate the resulting blast loads downstream of a cylindrical obstacle – both on the ground, and on a rigid wall target that the obstacle is aiming to protect. Inputs from this numerical study are also used to develop a fast-running predictive method based on an artificial neural network (ANN) model. It was found that the size of the cylinder, the strength of the blast wave, the position of the cylindrical obstruction, and the target length, all have remarkable effects on the development of the complex flow-field downstream, and on the impulse mitigation on a reflective target. A number of key mitigation mechanisms are identified, namely shadowing and interference, and their origins and significance are discussed. An ANN model trained using scaled input parameters could successfully predict impulse values on such a reflective target. Using this model to predict the response of previously unseen configurations (for the ANN) gave excellent correlation, thereby demonstrating the high fidelity of this fast-running tool, and its ability to predict the effectiveness of various wave-cylinder interactions in mitigating blast loading.
{"title":"Mitigation of blast loading through blast–obstacle interaction","authors":"Omar Ghareeb Alshammari, Obed Samuelraj Isaac, S. Clarke, S. Rigby","doi":"10.1177/20414196221115869","DOIUrl":"https://doi.org/10.1177/20414196221115869","url":null,"abstract":"Obstructing the passage of blast waves is an effective method of mitigating blast pressures downstream of the obstacle. To this end, the interaction between a blast wave and a simplified structural shape, such as a cylinder, has been widely investigated to understand the complex flow pattern that ensues around the obstacle. The patterns include the interference zones of the incident wave, the diffracted wave, and other secondary waves in the downstream region. Such zones are responsible for causing significant modifications to the blast wave parameters. This research aims to identify and study the factors that serve to mitigate the resulting blast loads downstream of a cylindrical obstacle – both on the ground, and on a rigid wall target that the obstacle is aiming to protect. Inputs from this numerical study are also used to develop a fast-running predictive method based on an artificial neural network (ANN) model. It was found that the size of the cylinder, the strength of the blast wave, the position of the cylindrical obstruction, and the target length, all have remarkable effects on the development of the complex flow-field downstream, and on the impulse mitigation on a reflective target. A number of key mitigation mechanisms are identified, namely shadowing and interference, and their origins and significance are discussed. An ANN model trained using scaled input parameters could successfully predict impulse values on such a reflective target. Using this model to predict the response of previously unseen configurations (for the ANN) gave excellent correlation, thereby demonstrating the high fidelity of this fast-running tool, and its ability to predict the effectiveness of various wave-cylinder interactions in mitigating blast loading.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"14 1","pages":"357 - 389"},"PeriodicalIF":2.0,"publicationDate":"2022-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49107608","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}
Reinforced concrete structures sometimes are deteriorated and damaged by seismic and blast wave loadings, and the resistance of fiber-reinforced concrete was tested at a loading of high-strain rate. Therefore, concrete structures were needed to improve the dynamic load resistance and energy absorption capabilities. In infrastructures, fiber is incorporated into concrete and is used to strengthen structures to increase its durability and resistance to high-strain rate loadings. In this study, the quasi-static and dynamic mechanical behaviors of Kevlar fiber-reinforced concrete were studied by the compressive strength test and Split Hopkinson Pressure Bar test, respectively. The 0.5% weight ratio Kevlar fiber content of KFRC specimens attained the highest strength in the quasi-static and dynamic test compared with benchmark and other 1.0%, 1.5% weight ratios. The KFRC specimens with the length of 12 mm and 24 mm exhibit similar effects in the quasi-static compressive strengths, but the KFRC specimens with the length of 24 mm fiber attained higher strain energies under dynamic loading.
{"title":"A study on mechanical behavior of Kevlar fiber reinforced concrete under static and high-strain rate loading","authors":"Yeou-Fong Li, Yanyan Huang, Jin-Yuan Syu, Ying-Kuan Tsai, Chih-Hong Huang","doi":"10.1177/20414196221118596","DOIUrl":"https://doi.org/10.1177/20414196221118596","url":null,"abstract":"Reinforced concrete structures sometimes are deteriorated and damaged by seismic and blast wave loadings, and the resistance of fiber-reinforced concrete was tested at a loading of high-strain rate. Therefore, concrete structures were needed to improve the dynamic load resistance and energy absorption capabilities. In infrastructures, fiber is incorporated into concrete and is used to strengthen structures to increase its durability and resistance to high-strain rate loadings. In this study, the quasi-static and dynamic mechanical behaviors of Kevlar fiber-reinforced concrete were studied by the compressive strength test and Split Hopkinson Pressure Bar test, respectively. The 0.5% weight ratio Kevlar fiber content of KFRC specimens attained the highest strength in the quasi-static and dynamic test compared with benchmark and other 1.0%, 1.5% weight ratios. The KFRC specimens with the length of 12 mm and 24 mm exhibit similar effects in the quasi-static compressive strengths, but the KFRC specimens with the length of 24 mm fiber attained higher strain energies under dynamic loading.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"14 1","pages":"407 - 437"},"PeriodicalIF":2.0,"publicationDate":"2022-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46130369","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 : 2022-08-12DOI: 10.1177/20414196221119234
Fengjiao Yang, N. Jiang, Chuan-bo Zhou, Guopeng Lyu, Yingkang Yao
To ensure the safety and stability of adjacent underground structures is a key problem for the subway tunnel blasting construction. In this paper, there is a tunnel group (Sheshan civil air defense engineering) composed of several tunnel units right above a subway tunnel under blasting construction (Wuhan Metro Line 5). The vibration of the tunnel group induced by two blasting excavations of the subway tunnel was monitored. For further research, an effective 3D numerical model established by LS-DYNA, which was verified by field monitoring data, was used to analyze the dynamic response of the tunnel group in the whole process of the subway tunnel blasting. According to the numerical simulation results, the dynamic response characteristics of each tunnel unit were studied, and the most vulnerable area in each tunnel unit was determined. Then, the functional relationships between the maximum vibration velocities and the maximum tensile stresses of the vulnerable areas were established. Based on the maximum tensile stress criterion, the safety vibration velocity threshold of each vulnerable area was calculated using the relationship models. Furthermore, for convenient field monitoring during the subway construction, the safety vibration threshold at the floor of the tunnel group was also calculated. Lastly, to obtain the maximum charge per delay, five cut blasting with different charges were simulated. The maximum charge of the cut blasting in different stages of the subway tunnel blasting excavation was proposed. The research results of this paper have reference value for the blasting vibration safety control of similar tunnel excavation projects in the future.
{"title":"Dynamic response and safety control of civil air defense tunnel group during the whole process of underpass tunnel blasting excavation","authors":"Fengjiao Yang, N. Jiang, Chuan-bo Zhou, Guopeng Lyu, Yingkang Yao","doi":"10.1177/20414196221119234","DOIUrl":"https://doi.org/10.1177/20414196221119234","url":null,"abstract":"To ensure the safety and stability of adjacent underground structures is a key problem for the subway tunnel blasting construction. In this paper, there is a tunnel group (Sheshan civil air defense engineering) composed of several tunnel units right above a subway tunnel under blasting construction (Wuhan Metro Line 5). The vibration of the tunnel group induced by two blasting excavations of the subway tunnel was monitored. For further research, an effective 3D numerical model established by LS-DYNA, which was verified by field monitoring data, was used to analyze the dynamic response of the tunnel group in the whole process of the subway tunnel blasting. According to the numerical simulation results, the dynamic response characteristics of each tunnel unit were studied, and the most vulnerable area in each tunnel unit was determined. Then, the functional relationships between the maximum vibration velocities and the maximum tensile stresses of the vulnerable areas were established. Based on the maximum tensile stress criterion, the safety vibration velocity threshold of each vulnerable area was calculated using the relationship models. Furthermore, for convenient field monitoring during the subway construction, the safety vibration threshold at the floor of the tunnel group was also calculated. Lastly, to obtain the maximum charge per delay, five cut blasting with different charges were simulated. The maximum charge of the cut blasting in different stages of the subway tunnel blasting excavation was proposed. The research results of this paper have reference value for the blasting vibration safety control of similar tunnel excavation projects in the future.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48812687","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 : 2022-08-12DOI: 10.1177/20414196221119239
Ke-wei Liu, M. Walske, Minbo Zhou, Xihong Zhang
The use of rammed earth (RE) as a construction material has recently received renewed interest due to its sustainability characteristics and potential for low-cost construction. Modern RE includes the addition of a binder to increase its performance. The mechanical performance of stabilised RE particularly the dynamic material properties is still not well understood. During the design life, a structure could experience dynamic loading. It is necessary to properly understand the dynamic properties of stabilised RE for safe applications. In this study, the quasi-static and dynamic material properties of cement and calcium carbonate residue (CCR) stabilised RE are experimentally investigated. The failure of the stabilised RE under different loading rates is investigated. Dynamic increase effect on cement and CCR stabilised RE are studied. The unconfined uniaxial compressive strength (UCS), Young’s modulus of the two types of stabilised RE at different strain rates are quantified. Empirical formulae of dynamic increase factor are derived for engineering application.
{"title":"The dynamic material properties of stabilised rammed earth materials using cement and calcium carbonate residue","authors":"Ke-wei Liu, M. Walske, Minbo Zhou, Xihong Zhang","doi":"10.1177/20414196221119239","DOIUrl":"https://doi.org/10.1177/20414196221119239","url":null,"abstract":"The use of rammed earth (RE) as a construction material has recently received renewed interest due to its sustainability characteristics and potential for low-cost construction. Modern RE includes the addition of a binder to increase its performance. The mechanical performance of stabilised RE particularly the dynamic material properties is still not well understood. During the design life, a structure could experience dynamic loading. It is necessary to properly understand the dynamic properties of stabilised RE for safe applications. In this study, the quasi-static and dynamic material properties of cement and calcium carbonate residue (CCR) stabilised RE are experimentally investigated. The failure of the stabilised RE under different loading rates is investigated. Dynamic increase effect on cement and CCR stabilised RE are studied. The unconfined uniaxial compressive strength (UCS), Young’s modulus of the two types of stabilised RE at different strain rates are quantified. Empirical formulae of dynamic increase factor are derived for engineering application.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48251776","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}
Concrete shrinkage usually results in the decrease in bearing capacity, durability and impact resistance of Concrete-Filled steel tube (CFST) structures during its service life. High strength expansive concrete (HSEC) is recently developed to deal with the shrinkage cracking in CFST structures. In this study, dynamic compressive tests and dynamic splitting tensile tests on the developed grade C60, C70 and C80 HSEC were performed using a split Hopkinson pressure bar device. Test results show that the expansive concrete is a typical rate-sensitive material, and its dynamic compressive strength and dynamic splitting tensile strength both increase with the strain rate. The compressive strength dynamic increase factor (DIFc) of HSEC is smaller than that of the ordinary concrete under the same strain rate, whereas the splitting tensile dynamic increase factor (DIFt) is larger than that of the ordinary concrete. All the test data were classified to establish calculation models of DIFc, peak toughness ( Rp), specific energy absorption (SEA), and DIFt, which provide a theoretical basis for the design and application of HSEC and CFST in engineering.
{"title":"Experimental study on dynamic compressive and splitting tensile properties of high strength expansive concrete","authors":"Qiyao Li, Li Chen, Chengjun Yue, Yuzhou Zheng, Jiayi Yuan, Xudong Chen","doi":"10.1177/20414196221119232","DOIUrl":"https://doi.org/10.1177/20414196221119232","url":null,"abstract":"Concrete shrinkage usually results in the decrease in bearing capacity, durability and impact resistance of Concrete-Filled steel tube (CFST) structures during its service life. High strength expansive concrete (HSEC) is recently developed to deal with the shrinkage cracking in CFST structures. In this study, dynamic compressive tests and dynamic splitting tensile tests on the developed grade C60, C70 and C80 HSEC were performed using a split Hopkinson pressure bar device. Test results show that the expansive concrete is a typical rate-sensitive material, and its dynamic compressive strength and dynamic splitting tensile strength both increase with the strain rate. The compressive strength dynamic increase factor (DIFc) of HSEC is smaller than that of the ordinary concrete under the same strain rate, whereas the splitting tensile dynamic increase factor (DIFt) is larger than that of the ordinary concrete. All the test data were classified to establish calculation models of DIFc, peak toughness ( Rp), specific energy absorption (SEA), and DIFt, which provide a theoretical basis for the design and application of HSEC and CFST in engineering.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45299261","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 : 2022-07-11DOI: 10.1177/20414196221114908
Antoine Gautier, I. Sochet, Sébastion Courtiaud, E. Lapebie
The aim of this study was to characterize the interaction of a shock wave with a parallelepipedal obstacle. Shock wave properties were quantified downstream of sixty configurations with different obstacle dimensions. With the introduction of new parameters, these experimental measurements were used to write evolution laws for the arrival time and the maximum overpressure downstream of a parallelepipedal obstacle. The accuracy of these laws was satisfactory. Then, the maximum overpressure law was compared with experimental measures from the literature. Despite differences in the obstacle geometry or experimental setup, these experimental data are in good agreement with the maximum overpressure law.
{"title":"Evaluation of shock wave properties interacting with a parallelepipedal obstacle","authors":"Antoine Gautier, I. Sochet, Sébastion Courtiaud, E. Lapebie","doi":"10.1177/20414196221114908","DOIUrl":"https://doi.org/10.1177/20414196221114908","url":null,"abstract":"The aim of this study was to characterize the interaction of a shock wave with a parallelepipedal obstacle. Shock wave properties were quantified downstream of sixty configurations with different obstacle dimensions. With the introduction of new parameters, these experimental measurements were used to write evolution laws for the arrival time and the maximum overpressure downstream of a parallelepipedal obstacle. The accuracy of these laws was satisfactory. Then, the maximum overpressure law was compared with experimental measures from the literature. Despite differences in the obstacle geometry or experimental setup, these experimental data are in good agreement with the maximum overpressure law.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"13 1","pages":"716 - 731"},"PeriodicalIF":2.0,"publicationDate":"2022-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45538452","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 : 2022-06-28DOI: 10.1177/20414196221112148
U. I. Cicek, D. Southee, A. Johnson
This paper investigates the effect of material extruded body armour specimen size on stab penetration depth and back-face signature (BFS) and establishes the minimum thickness required for a series of material extrusion materials to provide protection against the UK Home Office Scientific Development Branch (HOSDB) body armour KR1-E1 requirements. In stage one, material extruded planar test specimens ranging from 40 × 40 mm to 80 × 80 mm in length and width with 10 mm increments at three different thicknesses, 6, 8 and 10 mm, were stab tested under 24 joules of impact energy using a gravity driven drop test apparatus. In stage two, 50 × 50 mm specimens in six material categories, PC, ABS, PLA, TPLA, PA and TPU, were manufactured at different thicknesses via material extrusion and impacted in accordance with the UK HOSDB KR1-E1 stab impact energy level as they were the optimum size when considering overall stab and BFS performance. The study established the fundamental steps towards the use of material extrusion in future personal protection solutions. Results demonstrated that stab penetration and BFS were dependent on specimen size, thickness and material type, and there was an inverse relationship between stab penetration depth and BFS. Also, a minimum thickness of 5 mm for PC and TPLA, 6 mm for ABS, 7 mm for PLA, 11 mm for PA and 12 mm for TPU, with 100% print density, was required in order to provide protection against the HOSDB KR1-E1 level of 24 J stab impact energy.
{"title":"Assessing the stab resistive performance of material extruded body armour specimens","authors":"U. I. Cicek, D. Southee, A. Johnson","doi":"10.1177/20414196221112148","DOIUrl":"https://doi.org/10.1177/20414196221112148","url":null,"abstract":"This paper investigates the effect of material extruded body armour specimen size on stab penetration depth and back-face signature (BFS) and establishes the minimum thickness required for a series of material extrusion materials to provide protection against the UK Home Office Scientific Development Branch (HOSDB) body armour KR1-E1 requirements. In stage one, material extruded planar test specimens ranging from 40 × 40 mm to 80 × 80 mm in length and width with 10 mm increments at three different thicknesses, 6, 8 and 10 mm, were stab tested under 24 joules of impact energy using a gravity driven drop test apparatus. In stage two, 50 × 50 mm specimens in six material categories, PC, ABS, PLA, TPLA, PA and TPU, were manufactured at different thicknesses via material extrusion and impacted in accordance with the UK HOSDB KR1-E1 stab impact energy level as they were the optimum size when considering overall stab and BFS performance. The study established the fundamental steps towards the use of material extrusion in future personal protection solutions. Results demonstrated that stab penetration and BFS were dependent on specimen size, thickness and material type, and there was an inverse relationship between stab penetration depth and BFS. Also, a minimum thickness of 5 mm for PC and TPLA, 6 mm for ABS, 7 mm for PLA, 11 mm for PA and 12 mm for TPU, with 100% print density, was required in order to provide protection against the HOSDB KR1-E1 level of 24 J stab impact energy.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"14 1","pages":"335 - 356"},"PeriodicalIF":2.0,"publicationDate":"2022-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41398018","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 : 2022-05-30DOI: 10.1177/20414196221092466
R. Mourão, A. Caçoilo, F. Teixeira-Dias, A. Montalva, Hollice F. Stone, Eric Jacques
The response of structures subject to impulsive loads remains a field of intense research. Whilst traditional construction materials, such as steel and concrete/masonry, have been the focus of most studies, further research on the performance of alternative materials for blast-resistant applications has been driven by their growing use in sustainable construction. Over the last years, engineers have been re-evaluating the use of timber as a prime construction material for a range of building types, from small office to high-rise residential buildings. As a result, there is now a growing need to study the blast resistance of timber structures, as they may become potential targets of terrorist attacks or being placed in the blast-radius of other critical buildings. A review of existing research on the blast resistance of timber structures is presented and key factors on the blast analysis and design of such structures are discussed. Most of the research has been conducted on light-frame wood stud walls, glued- and cross-laminated timber, and addresses material properties under high strain rates, typical failure modes, behaviour of structural connections and retrofitting solutions. Failure modes are reported to be highly dependent on the element layout and manufacturing aspects, and dynamic increase factors for the modulus of elasticity and maximum strength in the ranges of [1.05, 1.43] and [1.14, 1.60], respectively, have been proposed for different timber elements. Mechanical connectors play a significant role in dissipating energy through plastic deformation, as the brittle nature of timber elements compromises the development of their full capacity. Regardless the element type, SDOF models can accurately predict the dynamic response as long as idealised boundary conditions can be considered. Overall, although a good amount of research is available, more extensive research is needed to guide the design and engineering practice and contribute to the development of design codes and testing standards for timber structures under blast loading.
{"title":"Blast resistance of timber structural elements: A state-of-the-art review","authors":"R. Mourão, A. Caçoilo, F. Teixeira-Dias, A. Montalva, Hollice F. Stone, Eric Jacques","doi":"10.1177/20414196221092466","DOIUrl":"https://doi.org/10.1177/20414196221092466","url":null,"abstract":"The response of structures subject to impulsive loads remains a field of intense research. Whilst traditional construction materials, such as steel and concrete/masonry, have been the focus of most studies, further research on the performance of alternative materials for blast-resistant applications has been driven by their growing use in sustainable construction. Over the last years, engineers have been re-evaluating the use of timber as a prime construction material for a range of building types, from small office to high-rise residential buildings. As a result, there is now a growing need to study the blast resistance of timber structures, as they may become potential targets of terrorist attacks or being placed in the blast-radius of other critical buildings. A review of existing research on the blast resistance of timber structures is presented and key factors on the blast analysis and design of such structures are discussed. Most of the research has been conducted on light-frame wood stud walls, glued- and cross-laminated timber, and addresses material properties under high strain rates, typical failure modes, behaviour of structural connections and retrofitting solutions. Failure modes are reported to be highly dependent on the element layout and manufacturing aspects, and dynamic increase factors for the modulus of elasticity and maximum strength in the ranges of [1.05, 1.43] and [1.14, 1.60], respectively, have been proposed for different timber elements. Mechanical connectors play a significant role in dissipating energy through plastic deformation, as the brittle nature of timber elements compromises the development of their full capacity. Regardless the element type, SDOF models can accurately predict the dynamic response as long as idealised boundary conditions can be considered. Overall, although a good amount of research is available, more extensive research is needed to guide the design and engineering practice and contribute to the development of design codes and testing standards for timber structures under blast loading.","PeriodicalId":46272,"journal":{"name":"International Journal of Protective Structures","volume":"14 1","pages":"263 - 295"},"PeriodicalIF":2.0,"publicationDate":"2022-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47108202","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 : 2022-05-27DOI: 10.1177/20414196221090989
H. Nikkhah, N. Naveed, Roghaiyeh Assaedi Beiragh, Sina Dadashzadeh, Q. Truong
This study aims to investigate the effects of the draw beads on the crashworthiness of the aluminum tubes under axial quasi-static loading. Based on this design philosophy, a total of 12 beading tube designs with various configurations were developed. Within each design, the effect of arrangement bead form on the crashworthiness performance was also analyzed. A finite element model, validated using experimental tests, was used to study the crashworthiness performance and progressive deformation of the tubes. Based on the results, a multi-criteria decision-making method known as Technique of Order Preference by Similarity to Ideal Solution was employed to determine the most suitable tube that features high energy absorption and low impact force. The best tube with a high score was selected to investigate the effect of bead formed direction on aluminum tubes. Consequently, the study identified a bead shape tubes configuration that exhibits superior crashworthiness and low impact force. The beading tube design methodology presented in this study allows the exploitation of variable shapes geometries for the development of high-efficiency energy-absorbing structures and their crushing behaviors.
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