Pub Date : 2022-05-17DOI: 10.2495/cmem-v10-n2-172-186
K. Panduranga, S. Koley
In this work, oblique wave scattering by a rectangular porous breakwater with slotted screens floating over a sill-type seabed is examined within the frame of linear wave–structure interaction theory. The Sollitt and Cross model is used to analyze the fluid motion inside the rectangular porous break- water. In addition, a quadratic pressure jump condition on the slotted screens is adopted to include the effect of wave height on wave attenuation by the slotted screens. The associated physical prob- lem is handled using an iterative boundary element method. Finally, the scattering coefficients such as the reflection, transmission, energy loss coefficients, and wave forces acting on the rectangular porous structure are analyzed for different wave conditions. The time-dependent displacement profiles for the various instants of time are provided. Further, the influence of different geometries of sill-type bottoms on wave scattering is analyzed. The study concludes that the wave forces on the rectangular structure attain their maximum when the distance between the slotted screen and the porous structure is an integral multiple of the wavelength associated with the incident wave for dif- ferent submergence drafts.
{"title":"Oblique wave scattering by a rectangular porous floating breakwater with slotted screens over a sill-type seabed","authors":"K. Panduranga, S. Koley","doi":"10.2495/cmem-v10-n2-172-186","DOIUrl":"https://doi.org/10.2495/cmem-v10-n2-172-186","url":null,"abstract":"In this work, oblique wave scattering by a rectangular porous breakwater with slotted screens floating over a sill-type seabed is examined within the frame of linear wave–structure interaction theory. The Sollitt and Cross model is used to analyze the fluid motion inside the rectangular porous break- water. In addition, a quadratic pressure jump condition on the slotted screens is adopted to include the effect of wave height on wave attenuation by the slotted screens. The associated physical prob- lem is handled using an iterative boundary element method. Finally, the scattering coefficients such as the reflection, transmission, energy loss coefficients, and wave forces acting on the rectangular porous structure are analyzed for different wave conditions. The time-dependent displacement profiles for the various instants of time are provided. Further, the influence of different geometries of sill-type bottoms on wave scattering is analyzed. The study concludes that the wave forces on the rectangular structure attain their maximum when the distance between the slotted screen and the porous structure is an integral multiple of the wavelength associated with the incident wave for dif- ferent submergence drafts.","PeriodicalId":36958,"journal":{"name":"International Journal of Computational Methods and Experimental Measurements","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74688092","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 : 2022-05-17DOI: 10.2495/cmem-v10-n2-158-171
Madhu Sudan Sapkota, E. Apeh, M. Hadfield, R. Haratian, R. Adey, J. Baynham
The process of developing a virtual replica of a physical asset usually involves using the best available values of the material and environment-related parameters essential to run the predictive simulation. The parameter values are further updated as necessary over time in response to the behaviour/condi- tions of physical assets and/or environment. This parametric calibration of the simulation models is usually made manually with trial-and-error using data obtained from sensors/manual survey readings of designated parts of the physical asset. Digital twining (DT) has provided a means by which validat- ing data from the physical asset can be obtained in near real time. However, the process of calibration is time-consuming as it is manual, and as with each parameter guess during the trial, a simulation run is required. This is even more so when the running time of a single simulation is high enough, like hours or even days, and the model involves a significantly high number of parameters. To address these shortcomings, an experimental platform implemented with the integration of a simulator and scientific software is proposed. The scientific software within the platform also offers surrogate building support, where surrogates assist in the estimation/update of design parameters as an alternative to time-consum-ing predictive models. The proposed platform is demonstrated using BEASY, a simulator designed to predict protection provided by a cathodic protection (CP) system to an asset, with MATLAB as the scientific software. The developed setup facilitates the task of model validation and adaptation of the CP model by automating the process within a DT ecosystem and also offers surrogate-assisted optimisation for parameter estimation/updating.
{"title":"Surrogate-assisted parametric calibration using design of experiment platform within digital twinning","authors":"Madhu Sudan Sapkota, E. Apeh, M. Hadfield, R. Haratian, R. Adey, J. Baynham","doi":"10.2495/cmem-v10-n2-158-171","DOIUrl":"https://doi.org/10.2495/cmem-v10-n2-158-171","url":null,"abstract":"The process of developing a virtual replica of a physical asset usually involves using the best available values of the material and environment-related parameters essential to run the predictive simulation. The parameter values are further updated as necessary over time in response to the behaviour/condi- tions of physical assets and/or environment. This parametric calibration of the simulation models is usually made manually with trial-and-error using data obtained from sensors/manual survey readings of designated parts of the physical asset. Digital twining (DT) has provided a means by which validat- ing data from the physical asset can be obtained in near real time. However, the process of calibration is time-consuming as it is manual, and as with each parameter guess during the trial, a simulation run is required. This is even more so when the running time of a single simulation is high enough, like hours or even days, and the model involves a significantly high number of parameters. To address these shortcomings, an experimental platform implemented with the integration of a simulator and scientific software is proposed. The scientific software within the platform also offers surrogate building support, where surrogates assist in the estimation/update of design parameters as an alternative to time-consum-ing predictive models. The proposed platform is demonstrated using BEASY, a simulator designed to predict protection provided by a cathodic protection (CP) system to an asset, with MATLAB as the scientific software. The developed setup facilitates the task of model validation and adaptation of the CP model by automating the process within a DT ecosystem and also offers surrogate-assisted optimisation for parameter estimation/updating.","PeriodicalId":36958,"journal":{"name":"International Journal of Computational Methods and Experimental Measurements","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83536846","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 : 2021-11-16DOI: 10.2495/cmem-v9-n4-296-308
M. Chiquito, S. Clubley, S. Martínez-Almajano, Anastasio P. Santos, R. Castedo, L. M. López
Masonry walls are one of the most widely used constructive elements in buildings. They offer a costeffective option and can satisfy many buildings requirements. However, their brittle composition leads them to generate high-speed debris under blast loads. Many casualties arise due to this kind of fragments. Strengthening of masonry walls is of much importance to increase safety inside the buildings. For this purpose, it is desirable to carry out field tests to assess the improvement of reinforcement measures, but the cost and complexity of these experiments can be very high. Therefore, numerical modelling is a good alternative to evaluate the behaviour of brick masonry walls under blast loads. Uncertainties in numerical modelling may be significant due to the composite nature of the reinforced masonry construction and the number of variables describing the constituent materials. In this work, a finite element simulation of a blast-loaded brick masonry wall validated with corresponding field tests is presented. A total of 24 brickwork masonry walls panels at full scale were tested in six different trials with explosives charges. In the configuration of each test, there was one unreinforced wall and three walls with different protective solutions. This paper focuses on the study of unreinforced walls. A 3D pure Lagrangian approach using LS-DYNA was developed with appropriate blast parameters derived from CONWEP, material models and suitable boundary conditions. Results of numerical modelling are compared in terms of wall displacement with the field data obtained in the trials. Study results show good agreement between the field test and the numerical modelling, demonstrating that the model is consistent and reliable.
{"title":"Numerical and experimental study of unreinforced brick masonry walls subjected to blast loads","authors":"M. Chiquito, S. Clubley, S. Martínez-Almajano, Anastasio P. Santos, R. Castedo, L. M. López","doi":"10.2495/cmem-v9-n4-296-308","DOIUrl":"https://doi.org/10.2495/cmem-v9-n4-296-308","url":null,"abstract":"Masonry walls are one of the most widely used constructive elements in buildings. They offer a costeffective option and can satisfy many buildings requirements. However, their brittle composition leads them to generate high-speed debris under blast loads. Many casualties arise due to this kind of fragments. Strengthening of masonry walls is of much importance to increase safety inside the buildings. For this purpose, it is desirable to carry out field tests to assess the improvement of reinforcement measures, but the cost and complexity of these experiments can be very high. Therefore, numerical modelling is a good alternative to evaluate the behaviour of brick masonry walls under blast loads. Uncertainties in numerical modelling may be significant due to the composite nature of the reinforced masonry construction and the number of variables describing the constituent materials. In this work, a finite element simulation of a blast-loaded brick masonry wall validated with corresponding field tests is presented. A total of 24 brickwork masonry walls panels at full scale were tested in six different trials with explosives charges. In the configuration of each test, there was one unreinforced wall and three walls with different protective solutions. This paper focuses on the study of unreinforced walls. A 3D pure Lagrangian approach using LS-DYNA was developed with appropriate blast parameters derived from CONWEP, material models and suitable boundary conditions. Results of numerical modelling are compared in terms of wall displacement with the field data obtained in the trials. Study results show good agreement between the field test and the numerical modelling, demonstrating that the model is consistent and reliable.","PeriodicalId":36958,"journal":{"name":"International Journal of Computational Methods and Experimental Measurements","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76356106","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 : 2021-11-16DOI: 10.2495/cmem-v9-n4-339-351
Koki Matsumoto, K. Takemura, H. Takagi, Tatsuya Tanaka, M. Sasada
Biofillers, lignocellulosic and cellulosic fillers have the potential to significantly improve the mechanical properties of polypropylene (PP) and reduce its carbon footprint by reducing the amount of petroleum-derived polymer used. In addition, the realization of fire retardancy of biofiller-filled PP composites is an important key topic to enhance their applications; ammonium polyphosphate (APP) is an effective fire retardant (FR). In this study, to ensure the reliability of biofillerand FR-filled PP composites, the creep properties were investigated in terms of the filler and FR content and filler type. In particular, the influence of APP addition into polymer composites on the creep properties has not been studied thoroughly. Two biofillers, wood flour (WF) and cellulose filler (CeF), with similar particle sizes and aspect ratios were used in this study. The creep test was conducted at a temperature of 80 °C in an accelerated test. Furthermore, the creep strain curves were modelled by the Burgers model of the viscoelastic constitutive equation to analyse the creep deformation behaviour. The incorporation of biofillers into the PP matrix significantly decreased the creep strain and improved the creep-rupture life with increasing filler content. Moreover, the creep-rupture life was longer for WF-filled PP composites than for CeF-filled PP composites. On the other hand, we found that incorporation of FR increased the creep rate at steady state and decreased the creep-rupture life of biofiller-filled PP composites, although the instantaneous creep strain decreased.
{"title":"Creep properties of biofiller- and fire retardant-filled polypropylene composites","authors":"Koki Matsumoto, K. Takemura, H. Takagi, Tatsuya Tanaka, M. Sasada","doi":"10.2495/cmem-v9-n4-339-351","DOIUrl":"https://doi.org/10.2495/cmem-v9-n4-339-351","url":null,"abstract":"Biofillers, lignocellulosic and cellulosic fillers have the potential to significantly improve the mechanical properties of polypropylene (PP) and reduce its carbon footprint by reducing the amount of petroleum-derived polymer used. In addition, the realization of fire retardancy of biofiller-filled PP composites is an important key topic to enhance their applications; ammonium polyphosphate (APP) is an effective fire retardant (FR). In this study, to ensure the reliability of biofillerand FR-filled PP composites, the creep properties were investigated in terms of the filler and FR content and filler type. In particular, the influence of APP addition into polymer composites on the creep properties has not been studied thoroughly. Two biofillers, wood flour (WF) and cellulose filler (CeF), with similar particle sizes and aspect ratios were used in this study. The creep test was conducted at a temperature of 80 °C in an accelerated test. Furthermore, the creep strain curves were modelled by the Burgers model of the viscoelastic constitutive equation to analyse the creep deformation behaviour. The incorporation of biofillers into the PP matrix significantly decreased the creep strain and improved the creep-rupture life with increasing filler content. Moreover, the creep-rupture life was longer for WF-filled PP composites than for CeF-filled PP composites. On the other hand, we found that incorporation of FR increased the creep rate at steady state and decreased the creep-rupture life of biofiller-filled PP composites, although the instantaneous creep strain decreased.","PeriodicalId":36958,"journal":{"name":"International Journal of Computational Methods and Experimental Measurements","volume":"94 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72449689","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 : 2021-11-16DOI: 10.2495/cmem-v9-n4-327-338
S. Trélat, M. Sturtzer, D. Eckenfels
Understanding the effects of blast generated by an accidental or a terroristic explosion nearby a critical structure is a main concern for the French Institute for Nuclear Safety (IRSN) and the French-German Research Institute of Saint Louis (ISL). Full-scale reactive phenomena are however seldomly compatible with long-term studies due to cost and regulation issues. Reduced scaled experimental work consequently represents an attractive alternative. Using small plastic explosive charges, blast effects in free-field or around various obstacles based on reference structures can be repeatedly examined, in order to provide the data necessary to develop simplified and numerical models. Following previous work on this topic by IRSN using a blast table and 42 g Hexomax® charges placed on its surface, ISL modified one existing blast pad to reproduce the same configuration at a double scale (333 g charges of Hexomax®). This study was conducted using a reference hemicylindrical obstacle, commonly encountered on industrial sites and also representative of certain transport containers. Numerous pressure sensors installed within the table or the pad thickness and on the surface of the hemicylinders provided the overpressure evolution for different values of the charge to obstacle distance. Explosive charges were ignited at distances up to 3.5 m/kg1/3 from the obstacle at ISL scale to extend the applicability domain of the model described in our previous document (Trélat et al. [18]) at a larger scale. The objective of this work is to assess not only blast effects on a potential target but also its capability to modify the blast propagation in its downstream space.
了解关键结构附近的意外爆炸或恐怖主义爆炸所产生的冲击波的影响是法国核安全研究所(IRSN)和法德圣路易斯研究所(ISL)的主要关注点。然而，由于成本和监管问题，全面反应现象很少与长期研究相容。因此，缩小规模的实验工作是一种有吸引力的选择。使用小型塑性炸药，可以在自由场或基于参考结构的各种障碍物周围反复检查爆炸效应，以便为开发简化和数值模型提供必要的数据。继IRSN之前在该主题上的工作之后，ISL修改了一个现有的爆炸垫，以双倍规模重现相同的配置(33g Hexomax®电荷)。本研究采用参考半圆柱形障碍物进行，这种障碍物通常在工业场所遇到，也代表某些运输集装箱。安装在工作台或垫层厚度内以及半圆柱体表面的多个压力传感器提供了不同装药值对障碍物距离的超压演变。在ISL尺度下，在距离障碍物3.5 m/ kg3 /3的距离上点燃炸药，以扩大我们之前的文献(trsamlate et al.[18])中描述的模型在更大尺度上的适用范围。这项工作的目的不仅是评估爆炸对潜在目标的影响，而且还评估其在下游空间中改变爆炸传播的能力。
{"title":"Towards a model to predict blast propagation around a hemicylindrical barrier","authors":"S. Trélat, M. Sturtzer, D. Eckenfels","doi":"10.2495/cmem-v9-n4-327-338","DOIUrl":"https://doi.org/10.2495/cmem-v9-n4-327-338","url":null,"abstract":"Understanding the effects of blast generated by an accidental or a terroristic explosion nearby a critical structure is a main concern for the French Institute for Nuclear Safety (IRSN) and the French-German Research Institute of Saint Louis (ISL). Full-scale reactive phenomena are however seldomly compatible with long-term studies due to cost and regulation issues. Reduced scaled experimental work consequently represents an attractive alternative. Using small plastic explosive charges, blast effects in free-field or around various obstacles based on reference structures can be repeatedly examined, in order to provide the data necessary to develop simplified and numerical models. Following previous work on this topic by IRSN using a blast table and 42 g Hexomax® charges placed on its surface, ISL modified one existing blast pad to reproduce the same configuration at a double scale (333 g charges of Hexomax®). This study was conducted using a reference hemicylindrical obstacle, commonly encountered on industrial sites and also representative of certain transport containers. Numerous pressure sensors installed within the table or the pad thickness and on the surface of the hemicylinders provided the overpressure evolution for different values of the charge to obstacle distance. Explosive charges were ignited at distances up to 3.5 m/kg1/3 from the obstacle at ISL scale to extend the applicability domain of the model described in our previous document (Trélat et al. [18]) at a larger scale. The objective of this work is to assess not only blast effects on a potential target but also its capability to modify the blast propagation in its downstream space.","PeriodicalId":36958,"journal":{"name":"International Journal of Computational Methods and Experimental Measurements","volume":"54 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78841003","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 : 2021-11-16DOI: 10.2495/cmem-v9-n4-365-380
S. Burrows, S. Forth, R. P. Sheldon
We demonstrate the capabilities of computational fluid dynamics (CFD) and a pressure-impulse failure model to predict blast loading and structural damage in a geometrically complex cityscape. The simulated loading is compared against experimental results for 69 g PE4 in a 1/50th scale model with wood-framed and plywood-faced buildings; data were collected from 11 pressure gauges throughout. In the initial simulation, geometric features were modeled as perfectly rigid, whereas buildings in the experiment failed: the resulting differences between the model and experiment allowed us to evaluate CFD when failure occurs. Simulated peak pressures during the first positive phase were still within 20% of experiment at most pressure gauges. However, errors in first phase impulses were around 40%, suggesting that building-failure effects are greater toward the phase end. Then, to model building-failure effects, we attempted to fit pressure-impulse failure curves to the plywood-faces: this proved too simplistic to produce realistic blast wave behavior due to the various, complex failure modes. This work illustrates key limitations of available CFD software and the pressure-impulse failure model – both industry-standard tools to determine structural response to blast. We conclude that stronger coupling between blast loading and structural response is needed where significant failure occurs.
我们展示了计算流体力学(CFD)和压力冲击失效模型在几何复杂的城市景观中预测爆炸载荷和结构损伤的能力。在木结构和胶合板结构的1/50比例模型中，将模拟载荷与69 g PE4的实验结果进行了比较;从11个压力表收集数据。在最初的模拟中，几何特征被建模为完全刚性的，而实验中的建筑物失败了:模型和实验之间的差异使我们能够在失败发生时评估CFD。在大多数压力表上，第一正相的模拟峰值压力仍在实验的20%以内。然而，第一阶段脉冲的误差约为40%，这表明建筑物的破坏效应在阶段结束时更大。然后，为了模拟建筑物的破坏效应，我们试图拟合胶合板表面的压力-脉冲破坏曲线:由于各种复杂的破坏模式，这种方法被证明过于简单，无法产生真实的冲击波行为。这项工作说明了现有CFD软件和压力冲击失效模型的主要局限性，这两种工具都是确定结构对爆炸响应的行业标准工具。我们得出结论，在发生重大破坏的地方，爆炸载荷和结构响应之间需要更强的耦合。
{"title":"Partial validation of CFD blast simulation in a cityscape environment featuring structural failure","authors":"S. Burrows, S. Forth, R. P. Sheldon","doi":"10.2495/cmem-v9-n4-365-380","DOIUrl":"https://doi.org/10.2495/cmem-v9-n4-365-380","url":null,"abstract":"We demonstrate the capabilities of computational fluid dynamics (CFD) and a pressure-impulse failure model to predict blast loading and structural damage in a geometrically complex cityscape. The simulated loading is compared against experimental results for 69 g PE4 in a 1/50th scale model with wood-framed and plywood-faced buildings; data were collected from 11 pressure gauges throughout. In the initial simulation, geometric features were modeled as perfectly rigid, whereas buildings in the experiment failed: the resulting differences between the model and experiment allowed us to evaluate CFD when failure occurs. Simulated peak pressures during the first positive phase were still within 20% of experiment at most pressure gauges. However, errors in first phase impulses were around 40%, suggesting that building-failure effects are greater toward the phase end. Then, to model building-failure effects, we attempted to fit pressure-impulse failure curves to the plywood-faces: this proved too simplistic to produce realistic blast wave behavior due to the various, complex failure modes. This work illustrates key limitations of available CFD software and the pressure-impulse failure model – both industry-standard tools to determine structural response to blast. We conclude that stronger coupling between blast loading and structural response is needed where significant failure occurs.","PeriodicalId":36958,"journal":{"name":"International Journal of Computational Methods and Experimental Measurements","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89826639","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 : 2021-11-16DOI: 10.2495/cmem-v9-n4-309-326
Sophie Eberhardt, M. Pospisil, P. Ryjáček, M. Sýkora
Survey of heritage structures, reliability assessment and subsequent design of appropriate interventions are disciplines where intensive multidisciplinary cooperation between architects, civil engineers and heritage preservation specialists is necessary. Surveys including visual inspections, measurements and tests provide vital information for reliability assessment. Non-destructive or minor-destructive tests are generally preferred in surveys of heritage structures. However, reliability assessments providing key information for decisions on structural interventions may require more detailed insights that may only be obtained by destructive tests. This is why incomplete information from a survey overly restricted to protect heritage values may lead to imprecise reliability assessment and to suboptimal decisions on structural interventions. As a consequence, such interventions may then lead to a loss of heritage value that might have been avoided. To provide guidance for practical applications, the submitted contribution presents an analysis of segments of heritage value that may be associated with buildings or bridges. Basis of the method was recently included into the Czech standard on assessment of existing structures. Sensitivity of each segment to the invasiveness of various methods of structural surveys is then discussed, considering also the potential need for input of reliability assessment. The presented framework is applied in the case study of a historic steel bridge located in the UNESCO site – historic centre of Prague. The contribution demonstrates that the segmentation of a heritage value by heritage preservation specialists and architects often helps to identify an optimal strategy for structural survey that provides sufficient information for detailed reliability assessment of the heritage structure. The case study presents a benchmark to be further developed and refined for its effective operational use in practice in the future.
{"title":"Heritage value assessment method – Application to historic steel bridgein prague","authors":"Sophie Eberhardt, M. Pospisil, P. Ryjáček, M. Sýkora","doi":"10.2495/cmem-v9-n4-309-326","DOIUrl":"https://doi.org/10.2495/cmem-v9-n4-309-326","url":null,"abstract":"Survey of heritage structures, reliability assessment and subsequent design of appropriate interventions are disciplines where intensive multidisciplinary cooperation between architects, civil engineers and heritage preservation specialists is necessary. Surveys including visual inspections, measurements and tests provide vital information for reliability assessment. Non-destructive or minor-destructive tests are generally preferred in surveys of heritage structures. However, reliability assessments providing key information for decisions on structural interventions may require more detailed insights that may only be obtained by destructive tests. This is why incomplete information from a survey overly restricted to protect heritage values may lead to imprecise reliability assessment and to suboptimal decisions on structural interventions. As a consequence, such interventions may then lead to a loss of heritage value that might have been avoided. To provide guidance for practical applications, the submitted contribution presents an analysis of segments of heritage value that may be associated with buildings or bridges. Basis of the method was recently included into the Czech standard on assessment of existing structures. Sensitivity of each segment to the invasiveness of various methods of structural surveys is then discussed, considering also the potential need for input of reliability assessment. The presented framework is applied in the case study of a historic steel bridge located in the UNESCO site – historic centre of Prague. The contribution demonstrates that the segmentation of a heritage value by heritage preservation specialists and architects often helps to identify an optimal strategy for structural survey that provides sufficient information for detailed reliability assessment of the heritage structure. The case study presents a benchmark to be further developed and refined for its effective operational use in practice in the future.","PeriodicalId":36958,"journal":{"name":"International Journal of Computational Methods and Experimental Measurements","volume":"63 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82445223","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 : 2021-11-16DOI: 10.2495/cmem-v9-n4-352-364
Jesus D. Ortega, I. Vazquez, P. Vorobieff, C. Ho
Particle size distribution is one of the most important physical properties of a particulate sample. Traditional particle-sizing methods to estimate a geometrical particle size distribution employ a sieve analysis (or gradation test), which entails filtering the particles through a series of sieves and measuring the weight remaining on each sieve to estimate the number-weighted particle size distribution. However, these two quantities have the same value only if particles are perfectly spherical and round. On the other hand, a particle sizer such as the Malvern particle size analyzer, which uses laser diagnostics to measure the particle sizes, can be a hefty investment. Alternatively, imaging techniques can be applied to estimate the size of these particles by scaling a reference dimension to the pixel size, which in turn is used to estimate the size of the visible particles. The focus of this work is to present a simple methodology using a DSLR camera and an illuminated LED panel to generate enough contrast. Using the camera and lens properties, the scale, or size, of any image can be obtained based on the mounting distance of the camera with respect to the target. An analysis tool was developed in MATLAB where the images are processed automatically based on the prescribed camera and lens properties embedded within the same image file and requiring the user to only input the mounting distance of the camera. So far, results show a positive agreement when comparing to measurements using ImageJ imaging tools and a sieve analysis. Future tests will analyze different particle sizes and types, as well as using a Malvern particle size analyzer to corroborate the results.
{"title":"A simple and fast matlab-based particle size distribution analysis tool","authors":"Jesus D. Ortega, I. Vazquez, P. Vorobieff, C. Ho","doi":"10.2495/cmem-v9-n4-352-364","DOIUrl":"https://doi.org/10.2495/cmem-v9-n4-352-364","url":null,"abstract":"Particle size distribution is one of the most important physical properties of a particulate sample. Traditional particle-sizing methods to estimate a geometrical particle size distribution employ a sieve analysis (or gradation test), which entails filtering the particles through a series of sieves and measuring the weight remaining on each sieve to estimate the number-weighted particle size distribution. However, these two quantities have the same value only if particles are perfectly spherical and round. On the other hand, a particle sizer such as the Malvern particle size analyzer, which uses laser diagnostics to measure the particle sizes, can be a hefty investment. Alternatively, imaging techniques can be applied to estimate the size of these particles by scaling a reference dimension to the pixel size, which in turn is used to estimate the size of the visible particles. The focus of this work is to present a simple methodology using a DSLR camera and an illuminated LED panel to generate enough contrast. Using the camera and lens properties, the scale, or size, of any image can be obtained based on the mounting distance of the camera with respect to the target. An analysis tool was developed in MATLAB where the images are processed automatically based on the prescribed camera and lens properties embedded within the same image file and requiring the user to only input the mounting distance of the camera. So far, results show a positive agreement when comparing to measurements using ImageJ imaging tools and a sieve analysis. Future tests will analyze different particle sizes and types, as well as using a Malvern particle size analyzer to corroborate the results.","PeriodicalId":36958,"journal":{"name":"International Journal of Computational Methods and Experimental Measurements","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80524797","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 : 2021-11-16DOI: 10.2495/cmem-v9-n4-283-295
A. Lugas, D. Aloj, D. Santoro, Vittoria Civilini, Simone Borrelli, C. Bignardi
Osteosynthesis is a surgical technique for the treatment of skeletal fractures through the implant of mechanical devices, such as plates and screws, in order to stabilize and fix the injured skeletal segment. It is preferred to the conservative treatment when the fracture requires immediate surgical correction or when, blocking the joints, degenerative changes could occur. Bone screws have different shapes and sizes depending on the intended use. In this study, six types of cortical bone screws were tested to determine the torque transmitted to the bone during the insertion. One Ti6Al4V tapered (Ø 6 mm) and five AISI 316L stainless steel – two straight (Ø 4 and 6 mm) and three tapered (Ø 4, 5, and 6 mm) – screws were used during the tests. Screws have been screwed into Sawbones (Sawbones® Pacific Research Laboratories, Inc., Vashon, USA) solid foam-type cylinders (external diameter 30 mm and thickness 3.5 mm) simulating the cortical bone diaphysis. Each of the 26 screws tested was inserted in a Sawbone cylinder five times, in five previously drawn equally spaced points, without any pilot holes. The experiment design was based on the ASTM standard for medical bone screws; two experienced orthopedic surgeons performed the insertions and removals of the screws using a hand-drill at 1 rev/s, aided by a metronome, and the torque was measured with a torsiometer throughout the tests. The mean and maximum torque resulted to be higher for larger diameter screws. Considering the same diameter, tapered screws showed a higher torque required for the extraction, which indicates stronger retention. However, in some cases, the Sawbones cylinder was fractured during the insertion of screws with a 6 mm diameter. Therefore, the use of medium-size tapered screws might be the most advisable compromise.
{"title":"Cortical bone screws constructive characteristics – A comparative study","authors":"A. Lugas, D. Aloj, D. Santoro, Vittoria Civilini, Simone Borrelli, C. Bignardi","doi":"10.2495/cmem-v9-n4-283-295","DOIUrl":"https://doi.org/10.2495/cmem-v9-n4-283-295","url":null,"abstract":"Osteosynthesis is a surgical technique for the treatment of skeletal fractures through the implant of mechanical devices, such as plates and screws, in order to stabilize and fix the injured skeletal segment. It is preferred to the conservative treatment when the fracture requires immediate surgical correction or when, blocking the joints, degenerative changes could occur. Bone screws have different shapes and sizes depending on the intended use. In this study, six types of cortical bone screws were tested to determine the torque transmitted to the bone during the insertion. One Ti6Al4V tapered (Ø 6 mm) and five AISI 316L stainless steel – two straight (Ø 4 and 6 mm) and three tapered (Ø 4, 5, and 6 mm) – screws were used during the tests. Screws have been screwed into Sawbones (Sawbones® Pacific Research Laboratories, Inc., Vashon, USA) solid foam-type cylinders (external diameter 30 mm and thickness 3.5 mm) simulating the cortical bone diaphysis. Each of the 26 screws tested was inserted in a Sawbone cylinder five times, in five previously drawn equally spaced points, without any pilot holes. The experiment design was based on the ASTM standard for medical bone screws; two experienced orthopedic surgeons performed the insertions and removals of the screws using a hand-drill at 1 rev/s, aided by a metronome, and the torque was measured with a torsiometer throughout the tests. The mean and maximum torque resulted to be higher for larger diameter screws. Considering the same diameter, tapered screws showed a higher torque required for the extraction, which indicates stronger retention. However, in some cases, the Sawbones cylinder was fractured during the insertion of screws with a 6 mm diameter. Therefore, the use of medium-size tapered screws might be the most advisable compromise.","PeriodicalId":36958,"journal":{"name":"International Journal of Computational Methods and Experimental Measurements","volume":"399 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84844321","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 : 2021-08-25DOI: 10.2495/cmem-v9-n3-238-248
F. Ávila, E. Puertas, R. Gallego
The increasing resource consumption, waste generation, and carbon footprint in the construction sector has drawn the attention of builders and researchers to alternative sustainable construction techniques and materials, such as rammed earth (RE). The mechanical behavior of RE is often enhanced through the use of diverse additives; although cement is probably the most common one, lime stabilization provides some important advantages, representing a more efficient and environmentally friendly solution with a long tradition in the improvement of the mechanical and hydraulic behavior of earthen materials. However, there are still several aspects regarding the effect of lime stabilization in RE mechanical properties that have not been thoroughly evaluated. In this regard, the present study analyze two of the main parameters concerning lime-stabilized rammed earth (LSRE), which are essential to ensure the correct use of this technique: the optimum lime content and the curing time. Several RE specimens with different lime contents, from 0 to 18% by weight, were manufactured and subjected to unconfined compression tests in order to obtain and compare their uniaxial compressive strength (UCS) and elastic modulus. An optimum lime content equal to 12% was obtained. Then, more LSRE samples with 12% lime were manufactured and tested at increasing curing times during 100 days to evaluate the development of their strength and stiffness. The results showed a logarithmic growth of both the UCS and the elastic modulus, with the majority of the strength (over 80%) developed during the first 30 days. In addition, non-destructive ultrasonic pulse velocity tests were carried out on the samples, proving to be a useful tool for predicting the mechanical properties of the material without damaging the specimens.
{"title":"Experimental evaluation of the optimum lime content and strength development of lime-stabilized rammed earth","authors":"F. Ávila, E. Puertas, R. Gallego","doi":"10.2495/cmem-v9-n3-238-248","DOIUrl":"https://doi.org/10.2495/cmem-v9-n3-238-248","url":null,"abstract":"The increasing resource consumption, waste generation, and carbon footprint in the construction sector has drawn the attention of builders and researchers to alternative sustainable construction techniques and materials, such as rammed earth (RE). The mechanical behavior of RE is often enhanced through the use of diverse additives; although cement is probably the most common one, lime stabilization provides some important advantages, representing a more efficient and environmentally friendly solution with a long tradition in the improvement of the mechanical and hydraulic behavior of earthen materials. However, there are still several aspects regarding the effect of lime stabilization in RE mechanical properties that have not been thoroughly evaluated. In this regard, the present study analyze two of the main parameters concerning lime-stabilized rammed earth (LSRE), which are essential to ensure the correct use of this technique: the optimum lime content and the curing time. Several RE specimens with different lime contents, from 0 to 18% by weight, were manufactured and subjected to unconfined compression tests in order to obtain and compare their uniaxial compressive strength (UCS) and elastic modulus. An optimum lime content equal to 12% was obtained. Then, more LSRE samples with 12% lime were manufactured and tested at increasing curing times during 100 days to evaluate the development of their strength and stiffness. The results showed a logarithmic growth of both the UCS and the elastic modulus, with the majority of the strength (over 80%) developed during the first 30 days. In addition, non-destructive ultrasonic pulse velocity tests were carried out on the samples, proving to be a useful tool for predicting the mechanical properties of the material without damaging the specimens.","PeriodicalId":36958,"journal":{"name":"International Journal of Computational Methods and Experimental Measurements","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85334758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：