Composite cement materials include concrete, reinforced concrete, fibred concrete, etc. The current research is focused on compressed concrete and reinforced concrete elements, loaded by forces, acting without eccentricity. The obtained results will form a basis for developing corresponding models for the above-mentioned materials as well as reinforced cement elements. This problem was investigated experimentally from the first studies on concrete as a composite material. It is still ongoing and attracts many researchers, performing experimental investigation to improve available empirical dependencies. According to modern design codes, the stress–strain diagram for compressed concrete is convex, the ultimate deformations in the plastic stage and in the descending branch are known, concrete behaves at the initial stage as an elastic material, etc. At the same time, there are no exact data on the ultimate elastic stress of concrete and corresponding deformation, ultimate stress of concrete at the descending branch, ultimate linear creep deformations, ductility parameter, etc. The authors have previously developed the structural phenomenon concept that solves the above-mentioned problems. As a result, accurate theoretical stress–strain relationship for compressed concrete is obtained. It also takes into account linear creep of compressed concrete. The theoretical model is recommended for effective design of compressed and bended high performance reinforced concrete elements. The results may also be included in modern codes related to high performance reinforced concrete elements and new cementtype materials.
{"title":"THEORETICAL STRESS–STRAIN MODEL FOR COMPRESSED COMPOSITE CEMENT MATERIALS","authors":"I. Iskhakov, Y. Ribakov","doi":"10.2495/HPSM180021","DOIUrl":"https://doi.org/10.2495/HPSM180021","url":null,"abstract":"Composite cement materials include concrete, reinforced concrete, fibred concrete, etc. The current research is focused on compressed concrete and reinforced concrete elements, loaded by forces, acting without eccentricity. The obtained results will form a basis for developing corresponding models for the above-mentioned materials as well as reinforced cement elements. This problem was investigated experimentally from the first studies on concrete as a composite material. It is still ongoing and attracts many researchers, performing experimental investigation to improve available empirical dependencies. According to modern design codes, the stress–strain diagram for compressed concrete is convex, the ultimate deformations in the plastic stage and in the descending branch are known, concrete behaves at the initial stage as an elastic material, etc. At the same time, there are no exact data on the ultimate elastic stress of concrete and corresponding deformation, ultimate stress of concrete at the descending branch, ultimate linear creep deformations, ductility parameter, etc. The authors have previously developed the structural phenomenon concept that solves the above-mentioned problems. As a result, accurate theoretical stress–strain relationship for compressed concrete is obtained. It also takes into account linear creep of compressed concrete. The theoretical model is recommended for effective design of compressed and bended high performance reinforced concrete elements. The results may also be included in modern codes related to high performance reinforced concrete elements and new cementtype materials.","PeriodicalId":340058,"journal":{"name":"High Performance and Optimum Design of Structures and Materials III","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115948195","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}
A cooling tower of a thermal power plant built in Slovenia a few years ago required a foundation system made of 30.00 m long piles. Because of the large number of piles the reduction of their length could lower the costs of foundation structure. To investigate such possibility it was necessary to study all factors that contributed to the bearing capacity of piles, especially the amount of load transferred to the soil through the skin of each pile. Therefore the vertical static load test of one pile was performed on a construction site with homogeneous geological and geotechnical soil conditions. The test pile was equipped with improved strain sensors built into the pile body. The vertical head displacements were also simultaneously measured. A massive concrete reaction frame was built to assure the support for the hydraulic jacks used for the introduction of the vertical load. During the vertical test the vertical load was increased until the soil below the pile toe collapsed. Since the time history of a complete state of strains along the pile was known, an accurate estimation of friction development along the pile shaft was performed. Also the development of soil settlements below the pile toe was obtained. Since the time history of applied force was also calculated from the measured strains, the change of the elastic modulus of pile concrete was estimated using equilibrium conditions. According to these results the length of each pile could be reduced by up to 12.00 m. Optimization of the pile length was performed in the frame of a special project by case study. The presented design method of piles using the experimental based total pile bearing capacity estimation proved itself as more effective and reliable than analytical methods usually used in geotechnical practice. Such tests are not very common because of average opinion that they are very demanding and expensive, but in this and several other similar cases it was proven that the costs and time can be significantly reduced without the loss of quality or safety of the structure.
{"title":"OPTIMIZATION OF THE PILE LENGTH ON THE BASIS OF PILE SKIN BEARING CAPACITY MEASUREMENTS","authors":"A. Štrukelj, B. Macuh","doi":"10.2495/HPSM180161","DOIUrl":"https://doi.org/10.2495/HPSM180161","url":null,"abstract":"A cooling tower of a thermal power plant built in Slovenia a few years ago required a foundation system made of 30.00 m long piles. Because of the large number of piles the reduction of their length could lower the costs of foundation structure. To investigate such possibility it was necessary to study all factors that contributed to the bearing capacity of piles, especially the amount of load transferred to the soil through the skin of each pile. Therefore the vertical static load test of one pile was performed on a construction site with homogeneous geological and geotechnical soil conditions. The test pile was equipped with improved strain sensors built into the pile body. The vertical head displacements were also simultaneously measured. A massive concrete reaction frame was built to assure the support for the hydraulic jacks used for the introduction of the vertical load. During the vertical test the vertical load was increased until the soil below the pile toe collapsed. Since the time history of a complete state of strains along the pile was known, an accurate estimation of friction development along the pile shaft was performed. Also the development of soil settlements below the pile toe was obtained. Since the time history of applied force was also calculated from the measured strains, the change of the elastic modulus of pile concrete was estimated using equilibrium conditions. According to these results the length of each pile could be reduced by up to 12.00 m. Optimization of the pile length was performed in the frame of a special project by case study. The presented design method of piles using the experimental based total pile bearing capacity estimation proved itself as more effective and reliable than analytical methods usually used in geotechnical practice. Such tests are not very common because of average opinion that they are very demanding and expensive, but in this and several other similar cases it was proven that the costs and time can be significantly reduced without the loss of quality or safety of the structure.","PeriodicalId":340058,"journal":{"name":"High Performance and Optimum Design of Structures and Materials III","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123535700","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}
In recent years, the demand for products of high quality, with hybrid properties, multifunctional, low cost and which is environmentally-friendly has been rapidly increasing. Here, several optimization technologies are currently being used to address these issues. Particularly, topology optimization technology is considered useful in the manufacturing field due to the high quality, high reliability and safety that it offers. However, it has been observed that there is a lack of proper material optimization techniques in the technology development process. There are hundreds of materials used in the industrial field but, surprisingly, there is a minimal amount of research regarding material property optimization for innovative developments. Thus, the present research, through a previously developed software, defined a material optimization technology for innovation. This technology relied on a software that creates new materials with hybrid properties, a hybrid materials manufacturing method, and an algorithm for material optimization. The material optimization technology was then evaluated. It is concluded from the results that: (1) the expanded proposed software was suitable for calculating the Young’s modulus, density, coefficient of linear expansion, specific heat and thermal conductivity for several properties; and (2) the material optimization technology was effective for the development of innovative products with defined functions or properties.
{"title":"DEVELOPMENT OF MATERIAL OPTIMIZATION TECHNOLOGY FOR INNOVATION","authors":"I. Tanabe, P. D. Silva","doi":"10.2495/HPSM180111","DOIUrl":"https://doi.org/10.2495/HPSM180111","url":null,"abstract":"In recent years, the demand for products of high quality, with hybrid properties, multifunctional, low cost and which is environmentally-friendly has been rapidly increasing. Here, several optimization technologies are currently being used to address these issues. Particularly, topology optimization technology is considered useful in the manufacturing field due to the high quality, high reliability and safety that it offers. However, it has been observed that there is a lack of proper material optimization techniques in the technology development process. There are hundreds of materials used in the industrial field but, surprisingly, there is a minimal amount of research regarding material property optimization for innovative developments. Thus, the present research, through a previously developed software, defined a material optimization technology for innovation. This technology relied on a software that creates new materials with hybrid properties, a hybrid materials manufacturing method, and an algorithm for material optimization. The material optimization technology was then evaluated. It is concluded from the results that: (1) the expanded proposed software was suitable for calculating the Young’s modulus, density, coefficient of linear expansion, specific heat and thermal conductivity for several properties; and (2) the material optimization technology was effective for the development of innovative products with defined functions or properties.","PeriodicalId":340058,"journal":{"name":"High Performance and Optimum Design of Structures and Materials III","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128078987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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