2012 |
|
 | Lie, Han Ay; Purnomo, Joko Modeling the Interfacial Transition Zone between Steel and Concrete Materials in Composite Constructions, 2012. @conference{20, title = {Modeling the Interfacial Transition Zone between Steel and Concrete Materials in Composite Constructions}, author = {Han Ay Lie and Joko Purnomo}, url = {https://www.researchgate.net/publication/260661125_Modeling_the_Interfacial_Transition_Zone_between_Steel_and_Concrete_Materials_in_Composite_Constructions }, doi = {10.3850/978-981-07-2615-7_123 }, year = {2012}, date = {2012-07-02}, booktitle = {Modeling the Interfacial Transition Zone between Steel and Concrete Materials in Composite Constructions}, journal = {Modeling the Interfacial Transition Zone between Steel and Concrete Materials in Composite Constructions}, abstract = {The interfacial Transition Zone (ITZ) has long been recognized as the “weak link” in a structure. While steel materials behave relatively linear till high stress levels, non-linearity is a prominent characteristic of most cementitious based material. To obtain a more realistic representation to the overall behavior of composite steel-to-concrete structures, the response of the interface should be incorporated into the analysis. A Finite Element Program written in the Visual Basic programming language was developed to take into account non-linearity of the cementitious materials, while incorporating the Interfacial Transition Zone behavior. The Transition Zone is modeled as two springs, perpendicular to each other. The individual load-deformation responses of the springs were obtained from laboratory tested specimens. The Federal Institute of Technology, Europe Model Code 2011 was used to model the cementitious material behavior. Failure criteria were analyzed based on the principal stresses at Gauss points. Keywords: ITZ, Spring, Stiffness Modulus, Failure Criteria.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } The interfacial Transition Zone (ITZ) has long been recognized as the “weak link” in a structure. While steel materials behave relatively linear till high stress levels, non-linearity is a prominent characteristic of most cementitious based material. To obtain a more realistic representation to the overall behavior of composite steel-to-concrete structures, the response of the interface should be incorporated into the analysis. A Finite Element Program written in the Visual Basic programming language was developed to take into account non-linearity of the cementitious materials, while incorporating the Interfacial Transition Zone behavior. The Transition Zone is modeled as two springs, perpendicular to each other. The individual load-deformation responses of the springs were obtained from laboratory tested specimens. The Federal Institute of Technology, Europe Model Code 2011 was used to model the cementitious material behavior. Failure criteria were analyzed based on the principal stresses at Gauss points. Keywords: ITZ, Spring, Stiffness Modulus, Failure Criteria. |
2011 |
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 | Han Ay Lie, Joko Purnomo Finite Element Modeling Incorporating Non-linearity of Material Behavior Based on the fib Model Code 2010 Journal Article Finite Element Modeling Incorporating Non-linearity of Material Behavior Based on the fib Model Code 2010, 5 (2), pp. 52-62, 2011. @article{23, title = {Finite Element Modeling Incorporating Non-linearity of Material Behavior Based on the fib Model Code 2010}, author = {Han Ay Lie, Joko Purnomo}, url = {https://academicpublishingplatforms.com/article.php?journal=ATI&number=5&article=770}, doi = {http://dx.doi.org/10.15208/ati.2011.13}, year = {2011}, date = {2011-11-01}, journal = {Finite Element Modeling Incorporating Non-linearity of Material Behavior Based on the fib Model Code 2010}, volume = {5}, number = {2}, pages = {52-62}, abstract = {Non-linearity is a prominent characteristic of most cement-based material. This nonlinear behavior is observed even at very low loading levels. When strain softening is present, the increase in loading will result in a decrease of structural stiffness. Most existing programs, including SAP 2000, takes into account geometric non-linearity, but assumes a constant stiffness modulus throughout the loading process. This will result in a less accurate outcome, and can further significantly influence analysis of the overall behavior of the structure. A Finite Element Program written in the Visual Basic programming language was developed to take into account non-linear behavior of the modulus of elasticity and the Poisson Ratio, as a function of increasing principal stresses. The results of this program were validated by laboratory tested specimens to compare the load-deformation response and accuracy of the model. The Federal Institute of Technology, Europe Model Code 2011 was used to model the material behavior and failure criterion. Keywords : Modulus, principal stresses, nonlinearity, FEM.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Non-linearity is a prominent characteristic of most cement-based material. This nonlinear behavior is observed even at very low loading levels. When strain softening is present, the increase in loading will result in a decrease of structural stiffness. Most existing programs, including SAP 2000, takes into account geometric non-linearity, but assumes a constant stiffness modulus throughout the loading process. This will result in a less accurate outcome, and can further significantly influence analysis of the overall behavior of the structure. A Finite Element Program written in the Visual Basic programming language was developed to take into account non-linear behavior of the modulus of elasticity and the Poisson Ratio, as a function of increasing principal stresses. The results of this program were validated by laboratory tested specimens to compare the load-deformation response and accuracy of the model. The Federal Institute of Technology, Europe Model Code 2011 was used to model the material behavior and failure criterion. Keywords : Modulus, principal stresses, nonlinearity, FEM. |
 | Lie, Han Ay; Sabdono, Parang Experimental Study to the Load-Displacement Response of the Interfacial Transition Zone in Concrete Conference Experimental Study to the Load-Displacement Response of the Interfacial Transition Zone in Concrete, 2011. @conference{24, title = {Experimental Study to the Load-Displacement Response of the Interfacial Transition Zone in Concrete}, author = {Han Ay Lie and Parang Sabdono}, url = {http://www.eacef.com/index.php?option=com_content&view=article&id=32&Itemid=38}, year = {2011}, date = {2011-09-20}, booktitle = {Experimental Study to the Load-Displacement Response of the Interfacial Transition Zone in Concrete}, abstract = {The Interfacial Transition Zone (ITZ) has been identified, and proven to be the “weak link” in concrete. At present, the existence of this ITZ is neglected, and the concrete is approached as a two-phase material, consisting of mortar and aggregates only. One major reason is that the mechanical behavior of this area; is not widely known. Since the dimension of this ITZ is very small, direct testing methods available are very limited. The micro indentation technique is up till now the only know straightforward method, but this test has its limitations as well. The purpose of this study was to develop a relatively simple procedure that will enable the measurement of displacement, as a function of load increment in the shear as well as the normal direction. The test results based on this approach showed that the response of the ITZ in the perpendicular direction to the aggregate surface follows a non-linear polynomial function, whereas the behavior parallel to the aggregate surface has a bi-linear response. Further investigation was focused on the effect of surface roughness, bleeding and area analysis. Keywords: interfacial transition zone, mortar, aggregates, stiffness (modulus) }, keywords = {}, pubstate = {published}, tppubtype = {conference} } The Interfacial Transition Zone (ITZ) has been identified, and proven to be the “weak link” in concrete. At present, the existence of this ITZ is neglected, and the concrete is approached as a two-phase material, consisting of mortar and aggregates only. One major reason is that the mechanical behavior of this area; is not widely known. Since the dimension of this ITZ is very small, direct testing methods available are very limited. The micro indentation technique is up till now the only know straightforward method, but this test has its limitations as well. The purpose of this study was to develop a relatively simple procedure that will enable the measurement of displacement, as a function of load increment in the shear as well as the normal direction. The test results based on this approach showed that the response of the ITZ in the perpendicular direction to the aggregate surface follows a non-linear polynomial function, whereas the behavior parallel to the aggregate surface has a bi-linear response. Further investigation was focused on the effect of surface roughness, bleeding and area analysis. Keywords: interfacial transition zone, mortar, aggregates, stiffness (modulus) |
2010 |
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 | Lie, Han Ay; Nuroji, Nuroji The Normal and Shear Modulus Properties of the Interfacial Transition Zone in Concrete; Newly Developed Testing Procedures, 2010. @conference{25, title = {The Normal and Shear Modulus Properties of the Interfacial Transition Zone in Concrete; Newly Developed Testing Procedures}, author = {Han Ay Lie and Nuroji Nuroji}, url = {https://www.researchgate.net/publication/260666968_THE_NORMAL_AND_SHEAR_MODULUS_PROPERTIES_OF_THE_INTERFACIAL_TRANSITION_ZONE_IN_CONCRETE_NEWLY_DEVELOPED_TESTING_PROCEDURES}, year = {2010}, date = {2010-08-01}, booktitle = {The Normal and Shear Modulus Properties of the Interfacial Transition Zone in Concrete; Newly Developed Testing Procedures}, abstract = {The transition zone of the aggregate surface adjacent to the mortar has a distinctive formation, in terms of its mechanical as well as its physical properties. This layer is recognized as the ITZ (Interfacial Transition Zone) and considered the “weak link”, since micro cracks are commonly initiated in this area. The properties of this ITZ only about 50 μm in dimension, are jet to be investigated. SEM (Scanning Electron Microscope) images can only provide qualitative information such as formation, type and relative amount of crystals; therefore other means are required to represent a better understanding to the behavior of the ITZ. The mechanical and physical properties of the ITZ are highly influenced by the differentiation in porosity and strength, as compared to the mortar matrix away from the ITZ. The modulus properties of the ITZ are investigated through newly developed laboratory testing techniques, resulting in load-to-area-displacement curves that can further be incorporated into mathematical or Finite Element Models. The normal and shear properties are tested by individual techniques, both resulting in the load-to-area versus displacement relationship of the ITZ. Further, this experimental study will evaluate the effect of bleeding and aggregate surface roughness to the ITZ’ normal and shear behavior. Two types of aggregates are studied; natural aggregates and steel-slag which is a residue of the steel industry and at present considered as a polluting waste. However, these testing techniques can be expanded to investigate the stiffness behavior of all cement based ITZ aggregates. Keywords: interfacial transition zone, mortar matrix, aggregate, shear and normal modulus}, keywords = {}, pubstate = {published}, tppubtype = {conference} } The transition zone of the aggregate surface adjacent to the mortar has a distinctive formation, in terms of its mechanical as well as its physical properties. This layer is recognized as the ITZ (Interfacial Transition Zone) and considered the “weak link”, since micro cracks are commonly initiated in this area. The properties of this ITZ only about 50 μm in dimension, are jet to be investigated. SEM (Scanning Electron Microscope) images can only provide qualitative information such as formation, type and relative amount of crystals; therefore other means are required to represent a better understanding to the behavior of the ITZ. The mechanical and physical properties of the ITZ are highly influenced by the differentiation in porosity and strength, as compared to the mortar matrix away from the ITZ. The modulus properties of the ITZ are investigated through newly developed laboratory testing techniques, resulting in load-to-area-displacement curves that can further be incorporated into mathematical or Finite Element Models. The normal and shear properties are tested by individual techniques, both resulting in the load-to-area versus displacement relationship of the ITZ. Further, this experimental study will evaluate the effect of bleeding and aggregate surface roughness to the ITZ’ normal and shear behavior. Two types of aggregates are studied; natural aggregates and steel-slag which is a residue of the steel industry and at present considered as a polluting waste. However, these testing techniques can be expanded to investigate the stiffness behavior of all cement based ITZ aggregates. Keywords: interfacial transition zone, mortar matrix, aggregate, shear and normal modulus |
2009 |
|
 | Lie, Han Ay; Nuroji, Nuroji Laboratory Testing and Modeling the Interfacial Transition Zone of Slag-Concrete Journal Article Laboratory Testing and Modeling the Interfacial Transition Zone of Slag-Concrete, 2009. @article{26, title = {Laboratory Testing and Modeling the Interfacial Transition Zone of Slag-Concrete}, author = {Han Ay Lie and Nuroji Nuroji}, url = {https://ejournal.undip.ac.id/index.php/mkts/article/view/5171}, doi = {https://doi.org/10.14710/mkts.v17i3.5171 }, year = {2009}, date = {2009-05-04}, journal = {Laboratory Testing and Modeling the Interfacial Transition Zone of Slag-Concrete}, abstract = {The transition zone at the aggregate surface has a distinctive formation, in terms of its mechanical as well as its physical properties. This layer is recognized as the ITZ (Interfacial Transition Zone) and considered the “weak link”, since micro cracks are commonly initiated in this area. The properties of this ITZ are jet to be investigated. SEM (Scanning Electron Microscope) images only provide qualitative information such as formation, type and relative amount of crystals. Therefore, other means are required to represent a better understanding to the behavior of the ITZ. The mechanical and physical properties of the ITZ are highly influenced by the differentiation in porosity and strength. A mathematical or FEM (Finite Element Model) can be used to bridge this lack of information. This paper deals with the the modeling approach of ITZ as well as the concept of laboratory testing for validation of the model. Kata kunci: model, interfacial transition zone, mortar, aggregate, kekakuan}, keywords = {}, pubstate = {published}, tppubtype = {article} } The transition zone at the aggregate surface has a distinctive formation, in terms of its mechanical as well as its physical properties. This layer is recognized as the ITZ (Interfacial Transition Zone) and considered the “weak link”, since micro cracks are commonly initiated in this area. The properties of this ITZ are jet to be investigated. SEM (Scanning Electron Microscope) images only provide qualitative information such as formation, type and relative amount of crystals. Therefore, other means are required to represent a better understanding to the behavior of the ITZ. The mechanical and physical properties of the ITZ are highly influenced by the differentiation in porosity and strength. A mathematical or FEM (Finite Element Model) can be used to bridge this lack of information. This paper deals with the the modeling approach of ITZ as well as the concept of laboratory testing for validation of the model. Kata kunci: model, interfacial transition zone, mortar, aggregate, kekakuan |
2007 |
|
 | Tudjono, Sri; Lie, Han Ay 2007. @proceedings{26b, title = {The Influence of Bearing Stiffeners to Double – Symmetrical I-Section’s Torsion Stiffness, an Analytical Approach}, author = {Sri Tudjono and Han Ay Lie }, url = {http://rpsonline.com.sg/proceedings/icass07/volume3/html/v3-rp0043.xml}, year = {2007}, date = {2007-12-05}, abstract = {Bearing Stiffeners are preventing web-local-buckling and reinforcing this section for point-loads and shear-forces. This paper discusses bearing stiffeners’ contribution in enhancing double-symmetric I-sections’ torsion capacity. Based on the Saint Venant’s formula torsion stresses are carried solemnly by the section, neglecting the stiffeners’ contribution. However, these stiffeners exhibit significant rotational deformation with the I-section in warping, indicating development of internal forces, restraining the warping. Therefore, the negligence of stiffeners’ contribution in Saint Venant’s torsion formula has to be revised. Torsions within the stiffeners are the Saint Venant’s and torsion-shear-stresses induced by bending. Assuming out-of-plane stresses neglected, normal and bending-shear torsion stresses are zero, leaving only the Saint Venant’s. From equilibrium at the stiffener-to-flange’s-joint, the stiffeners’ natural boundary conditions equation can be obtained. Their presence leads to a rotational-torsion function differentiation along the beam, between stiffeners. But since all points have identical internal torsion forces, the disturbed differential torsion warping equations are identical. Using the geometrical and natural boundary conditions equation the mathematical-rotational-torsion-solution for each field along the beam is obtained. It can be concluded that the member’s torsion stiffness increases approaching to linear while the increment will approach a hyperbola as a function of stiffeners’ number and thickness, respectively. }, keywords = {}, pubstate = {published}, tppubtype = {proceedings} } Bearing Stiffeners are preventing web-local-buckling and reinforcing this section for point-loads and shear-forces. This paper discusses bearing stiffeners’ contribution in enhancing double-symmetric I-sections’ torsion capacity. Based on the Saint Venant’s formula torsion stresses are carried solemnly by the section, neglecting the stiffeners’ contribution. However, these stiffeners exhibit significant rotational deformation with the I-section in warping, indicating development of internal forces, restraining the warping. Therefore, the negligence of stiffeners’ contribution in Saint Venant’s torsion formula has to be revised. Torsions within the stiffeners are the Saint Venant’s and torsion-shear-stresses induced by bending. Assuming out-of-plane stresses neglected, normal and bending-shear torsion stresses are zero, leaving only the Saint Venant’s. From equilibrium at the stiffener-to-flange’s-joint, the stiffeners’ natural boundary conditions equation can be obtained. Their presence leads to a rotational-torsion function differentiation along the beam, between stiffeners. But since all points have identical internal torsion forces, the disturbed differential torsion warping equations are identical. Using the geometrical and natural boundary conditions equation the mathematical-rotational-torsion-solution for each field along the beam is obtained. It can be concluded that the member’s torsion stiffness increases approaching to linear while the increment will approach a hyperbola as a function of stiffeners’ number and thickness, respectively. |
2012 |
|
| Lie, Han Ay; Purnomo, Joko Modeling the Interfacial Transition Zone between Steel and Concrete Materials in Composite Constructions, 2012. @conference{20, title = {Modeling the Interfacial Transition Zone between Steel and Concrete Materials in Composite Constructions}, author = {Han Ay Lie and Joko Purnomo}, url = {https://www.researchgate.net/publication/260661125_Modeling_the_Interfacial_Transition_Zone_between_Steel_and_Concrete_Materials_in_Composite_Constructions }, doi = {10.3850/978-981-07-2615-7_123 }, year = {2012}, date = {2012-07-02}, booktitle = {Modeling the Interfacial Transition Zone between Steel and Concrete Materials in Composite Constructions}, journal = {Modeling the Interfacial Transition Zone between Steel and Concrete Materials in Composite Constructions}, abstract = {The interfacial Transition Zone (ITZ) has long been recognized as the “weak link” in a structure. While steel materials behave relatively linear till high stress levels, non-linearity is a prominent characteristic of most cementitious based material. To obtain a more realistic representation to the overall behavior of composite steel-to-concrete structures, the response of the interface should be incorporated into the analysis. A Finite Element Program written in the Visual Basic programming language was developed to take into account non-linearity of the cementitious materials, while incorporating the Interfacial Transition Zone behavior. The Transition Zone is modeled as two springs, perpendicular to each other. The individual load-deformation responses of the springs were obtained from laboratory tested specimens. The Federal Institute of Technology, Europe Model Code 2011 was used to model the cementitious material behavior. Failure criteria were analyzed based on the principal stresses at Gauss points. Keywords: ITZ, Spring, Stiffness Modulus, Failure Criteria.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } The interfacial Transition Zone (ITZ) has long been recognized as the “weak link” in a structure. While steel materials behave relatively linear till high stress levels, non-linearity is a prominent characteristic of most cementitious based material. To obtain a more realistic representation to the overall behavior of composite steel-to-concrete structures, the response of the interface should be incorporated into the analysis. A Finite Element Program written in the Visual Basic programming language was developed to take into account non-linearity of the cementitious materials, while incorporating the Interfacial Transition Zone behavior. The Transition Zone is modeled as two springs, perpendicular to each other. The individual load-deformation responses of the springs were obtained from laboratory tested specimens. The Federal Institute of Technology, Europe Model Code 2011 was used to model the cementitious material behavior. Failure criteria were analyzed based on the principal stresses at Gauss points. Keywords: ITZ, Spring, Stiffness Modulus, Failure Criteria. |
2011 |
|
| Han Ay Lie, Joko Purnomo Finite Element Modeling Incorporating Non-linearity of Material Behavior Based on the fib Model Code 2010 Journal Article Finite Element Modeling Incorporating Non-linearity of Material Behavior Based on the fib Model Code 2010, 5 (2), pp. 52-62, 2011. @article{23, title = {Finite Element Modeling Incorporating Non-linearity of Material Behavior Based on the fib Model Code 2010}, author = {Han Ay Lie, Joko Purnomo}, url = {https://academicpublishingplatforms.com/article.php?journal=ATI&number=5&article=770}, doi = {http://dx.doi.org/10.15208/ati.2011.13}, year = {2011}, date = {2011-11-01}, journal = {Finite Element Modeling Incorporating Non-linearity of Material Behavior Based on the fib Model Code 2010}, volume = {5}, number = {2}, pages = {52-62}, abstract = {Non-linearity is a prominent characteristic of most cement-based material. This nonlinear behavior is observed even at very low loading levels. When strain softening is present, the increase in loading will result in a decrease of structural stiffness. Most existing programs, including SAP 2000, takes into account geometric non-linearity, but assumes a constant stiffness modulus throughout the loading process. This will result in a less accurate outcome, and can further significantly influence analysis of the overall behavior of the structure. A Finite Element Program written in the Visual Basic programming language was developed to take into account non-linear behavior of the modulus of elasticity and the Poisson Ratio, as a function of increasing principal stresses. The results of this program were validated by laboratory tested specimens to compare the load-deformation response and accuracy of the model. The Federal Institute of Technology, Europe Model Code 2011 was used to model the material behavior and failure criterion. Keywords : Modulus, principal stresses, nonlinearity, FEM.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Non-linearity is a prominent characteristic of most cement-based material. This nonlinear behavior is observed even at very low loading levels. When strain softening is present, the increase in loading will result in a decrease of structural stiffness. Most existing programs, including SAP 2000, takes into account geometric non-linearity, but assumes a constant stiffness modulus throughout the loading process. This will result in a less accurate outcome, and can further significantly influence analysis of the overall behavior of the structure. A Finite Element Program written in the Visual Basic programming language was developed to take into account non-linear behavior of the modulus of elasticity and the Poisson Ratio, as a function of increasing principal stresses. The results of this program were validated by laboratory tested specimens to compare the load-deformation response and accuracy of the model. The Federal Institute of Technology, Europe Model Code 2011 was used to model the material behavior and failure criterion. Keywords : Modulus, principal stresses, nonlinearity, FEM. |
| Lie, Han Ay; Sabdono, Parang Experimental Study to the Load-Displacement Response of the Interfacial Transition Zone in Concrete Conference Experimental Study to the Load-Displacement Response of the Interfacial Transition Zone in Concrete, 2011. @conference{24, title = {Experimental Study to the Load-Displacement Response of the Interfacial Transition Zone in Concrete}, author = {Han Ay Lie and Parang Sabdono}, url = {http://www.eacef.com/index.php?option=com_content&view=article&id=32&Itemid=38}, year = {2011}, date = {2011-09-20}, booktitle = {Experimental Study to the Load-Displacement Response of the Interfacial Transition Zone in Concrete}, abstract = {The Interfacial Transition Zone (ITZ) has been identified, and proven to be the “weak link” in concrete. At present, the existence of this ITZ is neglected, and the concrete is approached as a two-phase material, consisting of mortar and aggregates only. One major reason is that the mechanical behavior of this area; is not widely known. Since the dimension of this ITZ is very small, direct testing methods available are very limited. The micro indentation technique is up till now the only know straightforward method, but this test has its limitations as well. The purpose of this study was to develop a relatively simple procedure that will enable the measurement of displacement, as a function of load increment in the shear as well as the normal direction. The test results based on this approach showed that the response of the ITZ in the perpendicular direction to the aggregate surface follows a non-linear polynomial function, whereas the behavior parallel to the aggregate surface has a bi-linear response. Further investigation was focused on the effect of surface roughness, bleeding and area analysis. Keywords: interfacial transition zone, mortar, aggregates, stiffness (modulus) }, keywords = {}, pubstate = {published}, tppubtype = {conference} } The Interfacial Transition Zone (ITZ) has been identified, and proven to be the “weak link” in concrete. At present, the existence of this ITZ is neglected, and the concrete is approached as a two-phase material, consisting of mortar and aggregates only. One major reason is that the mechanical behavior of this area; is not widely known. Since the dimension of this ITZ is very small, direct testing methods available are very limited. The micro indentation technique is up till now the only know straightforward method, but this test has its limitations as well. The purpose of this study was to develop a relatively simple procedure that will enable the measurement of displacement, as a function of load increment in the shear as well as the normal direction. The test results based on this approach showed that the response of the ITZ in the perpendicular direction to the aggregate surface follows a non-linear polynomial function, whereas the behavior parallel to the aggregate surface has a bi-linear response. Further investigation was focused on the effect of surface roughness, bleeding and area analysis. Keywords: interfacial transition zone, mortar, aggregates, stiffness (modulus) |
2010 |
|
| Lie, Han Ay; Nuroji, Nuroji The Normal and Shear Modulus Properties of the Interfacial Transition Zone in Concrete; Newly Developed Testing Procedures, 2010. @conference{25, title = {The Normal and Shear Modulus Properties of the Interfacial Transition Zone in Concrete; Newly Developed Testing Procedures}, author = {Han Ay Lie and Nuroji Nuroji}, url = {https://www.researchgate.net/publication/260666968_THE_NORMAL_AND_SHEAR_MODULUS_PROPERTIES_OF_THE_INTERFACIAL_TRANSITION_ZONE_IN_CONCRETE_NEWLY_DEVELOPED_TESTING_PROCEDURES}, year = {2010}, date = {2010-08-01}, booktitle = {The Normal and Shear Modulus Properties of the Interfacial Transition Zone in Concrete; Newly Developed Testing Procedures}, abstract = {The transition zone of the aggregate surface adjacent to the mortar has a distinctive formation, in terms of its mechanical as well as its physical properties. This layer is recognized as the ITZ (Interfacial Transition Zone) and considered the “weak link”, since micro cracks are commonly initiated in this area. The properties of this ITZ only about 50 μm in dimension, are jet to be investigated. SEM (Scanning Electron Microscope) images can only provide qualitative information such as formation, type and relative amount of crystals; therefore other means are required to represent a better understanding to the behavior of the ITZ. The mechanical and physical properties of the ITZ are highly influenced by the differentiation in porosity and strength, as compared to the mortar matrix away from the ITZ. The modulus properties of the ITZ are investigated through newly developed laboratory testing techniques, resulting in load-to-area-displacement curves that can further be incorporated into mathematical or Finite Element Models. The normal and shear properties are tested by individual techniques, both resulting in the load-to-area versus displacement relationship of the ITZ. Further, this experimental study will evaluate the effect of bleeding and aggregate surface roughness to the ITZ’ normal and shear behavior. Two types of aggregates are studied; natural aggregates and steel-slag which is a residue of the steel industry and at present considered as a polluting waste. However, these testing techniques can be expanded to investigate the stiffness behavior of all cement based ITZ aggregates. Keywords: interfacial transition zone, mortar matrix, aggregate, shear and normal modulus}, keywords = {}, pubstate = {published}, tppubtype = {conference} } The transition zone of the aggregate surface adjacent to the mortar has a distinctive formation, in terms of its mechanical as well as its physical properties. This layer is recognized as the ITZ (Interfacial Transition Zone) and considered the “weak link”, since micro cracks are commonly initiated in this area. The properties of this ITZ only about 50 μm in dimension, are jet to be investigated. SEM (Scanning Electron Microscope) images can only provide qualitative information such as formation, type and relative amount of crystals; therefore other means are required to represent a better understanding to the behavior of the ITZ. The mechanical and physical properties of the ITZ are highly influenced by the differentiation in porosity and strength, as compared to the mortar matrix away from the ITZ. The modulus properties of the ITZ are investigated through newly developed laboratory testing techniques, resulting in load-to-area-displacement curves that can further be incorporated into mathematical or Finite Element Models. The normal and shear properties are tested by individual techniques, both resulting in the load-to-area versus displacement relationship of the ITZ. Further, this experimental study will evaluate the effect of bleeding and aggregate surface roughness to the ITZ’ normal and shear behavior. Two types of aggregates are studied; natural aggregates and steel-slag which is a residue of the steel industry and at present considered as a polluting waste. However, these testing techniques can be expanded to investigate the stiffness behavior of all cement based ITZ aggregates. Keywords: interfacial transition zone, mortar matrix, aggregate, shear and normal modulus |
2009 |
|
| Lie, Han Ay; Nuroji, Nuroji Laboratory Testing and Modeling the Interfacial Transition Zone of Slag-Concrete Journal Article Laboratory Testing and Modeling the Interfacial Transition Zone of Slag-Concrete, 2009. @article{26, title = {Laboratory Testing and Modeling the Interfacial Transition Zone of Slag-Concrete}, author = {Han Ay Lie and Nuroji Nuroji}, url = {https://ejournal.undip.ac.id/index.php/mkts/article/view/5171}, doi = {https://doi.org/10.14710/mkts.v17i3.5171 }, year = {2009}, date = {2009-05-04}, journal = {Laboratory Testing and Modeling the Interfacial Transition Zone of Slag-Concrete}, abstract = {The transition zone at the aggregate surface has a distinctive formation, in terms of its mechanical as well as its physical properties. This layer is recognized as the ITZ (Interfacial Transition Zone) and considered the “weak link”, since micro cracks are commonly initiated in this area. The properties of this ITZ are jet to be investigated. SEM (Scanning Electron Microscope) images only provide qualitative information such as formation, type and relative amount of crystals. Therefore, other means are required to represent a better understanding to the behavior of the ITZ. The mechanical and physical properties of the ITZ are highly influenced by the differentiation in porosity and strength. A mathematical or FEM (Finite Element Model) can be used to bridge this lack of information. This paper deals with the the modeling approach of ITZ as well as the concept of laboratory testing for validation of the model. Kata kunci: model, interfacial transition zone, mortar, aggregate, kekakuan}, keywords = {}, pubstate = {published}, tppubtype = {article} } The transition zone at the aggregate surface has a distinctive formation, in terms of its mechanical as well as its physical properties. This layer is recognized as the ITZ (Interfacial Transition Zone) and considered the “weak link”, since micro cracks are commonly initiated in this area. The properties of this ITZ are jet to be investigated. SEM (Scanning Electron Microscope) images only provide qualitative information such as formation, type and relative amount of crystals. Therefore, other means are required to represent a better understanding to the behavior of the ITZ. The mechanical and physical properties of the ITZ are highly influenced by the differentiation in porosity and strength. A mathematical or FEM (Finite Element Model) can be used to bridge this lack of information. This paper deals with the the modeling approach of ITZ as well as the concept of laboratory testing for validation of the model. Kata kunci: model, interfacial transition zone, mortar, aggregate, kekakuan |
2007 |
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| Tudjono, Sri; Lie, Han Ay 2007. @proceedings{26b, title = {The Influence of Bearing Stiffeners to Double – Symmetrical I-Section’s Torsion Stiffness, an Analytical Approach}, author = {Sri Tudjono and Han Ay Lie }, url = {http://rpsonline.com.sg/proceedings/icass07/volume3/html/v3-rp0043.xml}, year = {2007}, date = {2007-12-05}, abstract = {Bearing Stiffeners are preventing web-local-buckling and reinforcing this section for point-loads and shear-forces. This paper discusses bearing stiffeners’ contribution in enhancing double-symmetric I-sections’ torsion capacity. Based on the Saint Venant’s formula torsion stresses are carried solemnly by the section, neglecting the stiffeners’ contribution. However, these stiffeners exhibit significant rotational deformation with the I-section in warping, indicating development of internal forces, restraining the warping. Therefore, the negligence of stiffeners’ contribution in Saint Venant’s torsion formula has to be revised. Torsions within the stiffeners are the Saint Venant’s and torsion-shear-stresses induced by bending. Assuming out-of-plane stresses neglected, normal and bending-shear torsion stresses are zero, leaving only the Saint Venant’s. From equilibrium at the stiffener-to-flange’s-joint, the stiffeners’ natural boundary conditions equation can be obtained. Their presence leads to a rotational-torsion function differentiation along the beam, between stiffeners. But since all points have identical internal torsion forces, the disturbed differential torsion warping equations are identical. Using the geometrical and natural boundary conditions equation the mathematical-rotational-torsion-solution for each field along the beam is obtained. It can be concluded that the member’s torsion stiffness increases approaching to linear while the increment will approach a hyperbola as a function of stiffeners’ number and thickness, respectively. }, keywords = {}, pubstate = {published}, tppubtype = {proceedings} } Bearing Stiffeners are preventing web-local-buckling and reinforcing this section for point-loads and shear-forces. This paper discusses bearing stiffeners’ contribution in enhancing double-symmetric I-sections’ torsion capacity. Based on the Saint Venant’s formula torsion stresses are carried solemnly by the section, neglecting the stiffeners’ contribution. However, these stiffeners exhibit significant rotational deformation with the I-section in warping, indicating development of internal forces, restraining the warping. Therefore, the negligence of stiffeners’ contribution in Saint Venant’s torsion formula has to be revised. Torsions within the stiffeners are the Saint Venant’s and torsion-shear-stresses induced by bending. Assuming out-of-plane stresses neglected, normal and bending-shear torsion stresses are zero, leaving only the Saint Venant’s. From equilibrium at the stiffener-to-flange’s-joint, the stiffeners’ natural boundary conditions equation can be obtained. Their presence leads to a rotational-torsion function differentiation along the beam, between stiffeners. But since all points have identical internal torsion forces, the disturbed differential torsion warping equations are identical. Using the geometrical and natural boundary conditions equation the mathematical-rotational-torsion-solution for each field along the beam is obtained. It can be concluded that the member’s torsion stiffness increases approaching to linear while the increment will approach a hyperbola as a function of stiffeners’ number and thickness, respectively. |
