This study is motivated by the need to develop an efficient numerical model to simulate nonunifor... more This study is motivated by the need to develop an efficient numerical model to simulate nonuniform interfacial degradation of reinforcing steel in concrete in an accelerated corrosion setup. In this study, a multi-physics finite element (FE) model is presented that takes into consideration the spatial and temporal non-uniformity of corrosion induced degradation in rebar, and eliminates the assumption of uniform mass loss and its linear variation with time as per available literature that uses classical approach of Faraday's law. The model is validated experimentally with accelerated corrosion setup designed to induce partial corrosion. Further, the possibility of extending this model to monitor natural corrosion is discussed with required modifications. Unlike previous studies, pore saturation (PS) is continuously monitored and its existing experimental correlations with electrolyte conductivity and oxygen diffusivity in the vicinity of partial corrosion are adopted so that the model can be extended to simulate natural corrosion. These evaluations can be made completely nondestructive and in real time to capture the influence of local environment. The proposed methodology also captures the effect of differential aeration pertaining to local exposure. Therefore, the challenges in incorporating influence of local environment by the use of alternative parameters such as relative humidity from real climate change predictions are eliminated. It is shown that the multi-physics model is effective and convenient to simulate the non-uniform time dependent mass loss with acceptable accuracy and that its capability can be extended to monitor natural non uniform corrosion on a space-time frame.
Dynamic analysis of laminated composite plates using a layer-wise mixed finite element model
Composite Structures, Feb 1, 2003
This paper deals with an accurate, three-dimensional, higher order, mixed finite element (FE) mod... more This paper deals with an accurate, three-dimensional, higher order, mixed finite element (FE) modeling for the free vibration analysis of multi-layered thick composite plates. An 18-node, three-dimensional mixed FE model has been developed by using Hamilton’s energy principle. Continuity of the transverse stress and the displacement fields has been enforced through the thickness of laminated composite plate. Further, in addition
Proceedings of the Indian National Science Academy. Part A, Physical Sciences, Sep 1, 2016
An effort has been made in this paper to analyze a simple diaphragm supported single layer piezoe... more An effort has been made in this paper to analyze a simple diaphragm supported single layer piezoelectric plate for electromechanical loading by using mixed semi-analytical model developed by Kant et al. (2007). The mathematical model consists of defining a two-point boundary value problem (BVP) governed by a set of coupled first order ordinary differential equations (ODEs). The accuracy and effectiveness of the proposed model are assessed by comparing the numerical results with available three dimensional (3D) elasticity solutions. Numerical results for different length to width ratio and for various aspect ratios have been presented for future reference.
Nonlinear analysis of reinforced concrete beams strengthened with polymer composites
Structural Engineering and Mechanics, Sep 10, 2006
Strengthening of existing old structures has traditionally been accomplished by using conventiona... more Strengthening of existing old structures has traditionally been accomplished by using conventional materials and techniques, viz., externally bonded steel plates, steel or concrete jackets, etc. Alternatively, fibre reinforced polymer composite (FRPC) products started being used to overcome problems associated with conventional materials in the mid 1950s because of their favourable engineering properties. Effectiveness of FRPC materials has been demonstrated through extensive experimental research throughout the world in the last two decades. However there is a need to use refined analytical tools to simulate response of strengthened system. In this paper, an attempt has been made to develop a numerical model of strengthened reinforced concrete (RC) beams with FRPC laminates. Material models for RC beams strengthened with FRPC laminates are described and verified through a nonlinear finite element (FE) commercial code, with the help of available experimental data. Three dimensional (3D) FE analysis has been performed by assuming perfect bonding between concrete and FRPC laminate. A parametric study has also been performed to examine effects of various parameters like fibre type, stirrup`s spacing, etc. on the strengthening system. Through numerical simulation, it has been shown that it is possible to predict accurately the flexural response of RC beams strengthened with FRPC laminates by selecting an appropriate material constitutive model. Comparisons are made between the available experimental results in literature and FE analysis results obtained by the present investigators using load-deflection and load-strain plots as well as ultimate load of the strengthened beams. Furthermore, evaluation of crack patterns from FE analysis and experimental failure modes are discussed at the end.
Behavior of Concrete Columns Confined by Fiber Composites. Discussion and Closure
Journal of Structural Engineering-asce, Sep 1, 1998
A discussion of a paper with the aforementioned title by A. Mirmiran and M. Shahawy, published in... more A discussion of a paper with the aforementioned title by A. Mirmiran and M. Shahawy, published in this journal (Volume 123, Number 5, May 1997), is presented. The discussers question the authors' development of the theoretical model assuming axisymmetric behavior throughout the process of deformation and offer the results of some of their own experiments that did not reinforce the axisymmetric model. They conclude that the axisymmetric model is inadequate to predict the failure mode of concrete-filled fiber reinforced polymer composite tubes. Discussion is followed by closure from the authors.
Construction Applications of Fiber Reinforced Polymer Composites: A Survey
A review is made of the different applications of fiber reinforced polymer composite (FRPC) mater... more A review is made of the different applications of fiber reinforced polymer composite (FRPC) materials and carbon fiber reinforced plastic (CFRP) cables in construction. The potential FRPC application areas are classified into three groups, namely: (i) Repair and rehabilitation of structural elements using FRPC sheets, (ii) FRPC bars as a reinforcement material for concrete structural elements, and (iii) Structural elements made of FRPC. Literature relevant to FRPC material in construction is divided into the above three groups. This review focuses on experimental research only. No attempt has been made to identify different analytical studies available on FRPC. Sub-topics of the above three areas are mentioned along with partial references
FEATURE ARTICLE: Items of special interest, tutorials, and surveys: Static and Dynamic Behav Ior of Mechanical Components Associated With Electrical Transmission Lines -- Iii (a)
A semi-analytical method incorporating various displacement based formulations has been developed... more A semi-analytical method incorporating various displacement based formulations has been developed to investigate scattering of waves in composite laminated plates. Plane strain condition in composite laminated plate due to propagation of a time harmonicwave and vibrations has been investigated.Various displacement based models have been developed by using combinations of linear, quadratic, cubic and quartic variation of displacements through thickness of the lamina. Results obtained using various displacement models are compared for isotropic, orthotropic and composite laminated plates. The higher order displacement based theory using cubic variation of in-plane and transverse displacements through thickness of lamina is found to be most accurate and economical one for analyzing scattering of waves in composite laminated plates.
This study is motivated by the need to develop an efficient numerical model to simulate non-unifo... more This study is motivated by the need to develop an efficient numerical model to simulate non-uniform interfacial degradation of reinforcing steel in concrete in an accelerated corrosion setup considering the influence of differential aeration, moisture and conductivity. In this study, a multi-physics finite element (FE) model is presented to simulate spatially and temporally non-uniform surface topography of corroding steel with rust layer, and eliminates the assumption of uniform mass loss and its linear variation with time as per available literature that uses classical approach of Faraday’s law. The model is validated experimentally with accelerated corrosion setup. Unlike previous studies, pore saturation (PS) is continuously monitored and its existing experimental correlations with conductivity and oxygen diffusivity are adopted so that the model can be extended to simulate natural corrosion to enhance the accuracy of service life predictions. These evaluations can be made compl...
Analytical and numerical investigations of the flexure of isotropic plates using the novel first-order shear deformation theory
Proceedings of the Indian National Science Academy, 2021
A variant of the first-order shear deformation theory is presented for the flexure of shear defor... more A variant of the first-order shear deformation theory is presented for the flexure of shear deformable linear isotropic plates undergoing small deformations. The principle of stationary potential energy is utilized to obtain governing differential equations and variationally consistent boundary conditions. Unlike the Mindlin’s plate theory, the presented variant involves two coupled governing partial differential equations involving two unknown functions. This reduction will result in saving of the computational time involved for the plate boundary value problem, especially when external forces acting on the plate are variable/non-linear in nature. Solutions for the flexure of shear deformable isotropic plates by utilizing Levy’s method are obtained using analytical and numerical techniques. The fourth-order Runge–Kutta technique is utilized for obtaining numerical solutions. The effect of the plate thickness-to-length ratio on the flexure of shear deformable isotropic plates with two opposite edges simply-supported and remaining two edges having different combinations of boundary conditions are presented. These results are compared with corresponding results available in the literature.
Invited: Multi-model finite element approach for stress analysis of composite laminates
A multi-model global-local approach to study free edge effects in laminated composites subjected ... more A multi-model global-local approach to study free edge effects in laminated composites subjected to uniaxial in-plane loads is presented in this paper. Mixed layer-wise (LW) finite element (FE) model is used in critical free edge zone. Remaining part of plate is modelled by using higher order equivalent single layer (ESL) theory. A transition element is developed to ensure a compatibility between differently modelled subdomains. This combined model possesses traits of both ESL and LW mixed models. Higher order ESL predicts global parameters efficiently, on the other hand, mixed LW model captures the interlaminar stresses at local zones. Mixed LW model includes the transverse stresses as nodal degrees of freedom (DOF) ensuring continuity of the transverse stresses over layer interfaces without using any additional stress functions. Both, ESL and LW mixed models are developed by using three dimensional (3D) elasticity relationships and principle of minimum potential energy. The presen...
Uneven distribution of fibers can adversely affect the mechanical behavior of unidirectional comp... more Uneven distribution of fibers can adversely affect the mechanical behavior of unidirectional composites. A micromechanical model based on finite element analysis is presented to evaluate elastic and strength properties of such composites under normal loading. Analysis starts with identification of micro unit cells/micro repetitive unit cells and/or representative volume elements. Because of uneven distribution/random distribution of the fibers, fiber volume fraction can be different for different micro unit cells present at different locations in the transverse cross-section of the unidirectional composite. Configuration of the micro unit cell is worked out at the outset considering the fiber distribution having the hexagonal arrangement, but with different volume fraction at different locations. For such micro unit cells, elastic and strength properties are obtained based on finite element analysis starting with the elastic and strength properties of fiber and matrix. With the prop...
This study is motivated by the need to develop an efficient numerical model to simulate nonunifor... more This study is motivated by the need to develop an efficient numerical model to simulate nonuniform interfacial degradation of reinforcing steel in concrete in an accelerated corrosion setup. In this study, a multi-physics finite element (FE) model is presented that takes into consideration the spatial and temporal non-uniformity of corrosion induced degradation in rebar, and eliminates the assumption of uniform mass loss and its linear variation with time as per available literature that uses classical approach of Faraday's law. The model is validated experimentally with accelerated corrosion setup designed to induce partial corrosion. Further, the possibility of extending this model to monitor natural corrosion is discussed with required modifications. Unlike previous studies, pore saturation (PS) is continuously monitored and its existing experimental correlations with electrolyte conductivity and oxygen diffusivity in the vicinity of partial corrosion are adopted so that the model can be extended to simulate natural corrosion. These evaluations can be made completely nondestructive and in real time to capture the influence of local environment. The proposed methodology also captures the effect of differential aeration pertaining to local exposure. Therefore, the challenges in incorporating influence of local environment by the use of alternative parameters such as relative humidity from real climate change predictions are eliminated. It is shown that the multi-physics model is effective and convenient to simulate the non-uniform time dependent mass loss with acceptable accuracy and that its capability can be extended to monitor natural non uniform corrosion on a space-time frame.
Dynamic analysis of laminated composite plates using a layer-wise mixed finite element model
Composite Structures, Feb 1, 2003
This paper deals with an accurate, three-dimensional, higher order, mixed finite element (FE) mod... more This paper deals with an accurate, three-dimensional, higher order, mixed finite element (FE) modeling for the free vibration analysis of multi-layered thick composite plates. An 18-node, three-dimensional mixed FE model has been developed by using Hamilton’s energy principle. Continuity of the transverse stress and the displacement fields has been enforced through the thickness of laminated composite plate. Further, in addition
Proceedings of the Indian National Science Academy. Part A, Physical Sciences, Sep 1, 2016
An effort has been made in this paper to analyze a simple diaphragm supported single layer piezoe... more An effort has been made in this paper to analyze a simple diaphragm supported single layer piezoelectric plate for electromechanical loading by using mixed semi-analytical model developed by Kant et al. (2007). The mathematical model consists of defining a two-point boundary value problem (BVP) governed by a set of coupled first order ordinary differential equations (ODEs). The accuracy and effectiveness of the proposed model are assessed by comparing the numerical results with available three dimensional (3D) elasticity solutions. Numerical results for different length to width ratio and for various aspect ratios have been presented for future reference.
Nonlinear analysis of reinforced concrete beams strengthened with polymer composites
Structural Engineering and Mechanics, Sep 10, 2006
Strengthening of existing old structures has traditionally been accomplished by using conventiona... more Strengthening of existing old structures has traditionally been accomplished by using conventional materials and techniques, viz., externally bonded steel plates, steel or concrete jackets, etc. Alternatively, fibre reinforced polymer composite (FRPC) products started being used to overcome problems associated with conventional materials in the mid 1950s because of their favourable engineering properties. Effectiveness of FRPC materials has been demonstrated through extensive experimental research throughout the world in the last two decades. However there is a need to use refined analytical tools to simulate response of strengthened system. In this paper, an attempt has been made to develop a numerical model of strengthened reinforced concrete (RC) beams with FRPC laminates. Material models for RC beams strengthened with FRPC laminates are described and verified through a nonlinear finite element (FE) commercial code, with the help of available experimental data. Three dimensional (3D) FE analysis has been performed by assuming perfect bonding between concrete and FRPC laminate. A parametric study has also been performed to examine effects of various parameters like fibre type, stirrup`s spacing, etc. on the strengthening system. Through numerical simulation, it has been shown that it is possible to predict accurately the flexural response of RC beams strengthened with FRPC laminates by selecting an appropriate material constitutive model. Comparisons are made between the available experimental results in literature and FE analysis results obtained by the present investigators using load-deflection and load-strain plots as well as ultimate load of the strengthened beams. Furthermore, evaluation of crack patterns from FE analysis and experimental failure modes are discussed at the end.
Behavior of Concrete Columns Confined by Fiber Composites. Discussion and Closure
Journal of Structural Engineering-asce, Sep 1, 1998
A discussion of a paper with the aforementioned title by A. Mirmiran and M. Shahawy, published in... more A discussion of a paper with the aforementioned title by A. Mirmiran and M. Shahawy, published in this journal (Volume 123, Number 5, May 1997), is presented. The discussers question the authors' development of the theoretical model assuming axisymmetric behavior throughout the process of deformation and offer the results of some of their own experiments that did not reinforce the axisymmetric model. They conclude that the axisymmetric model is inadequate to predict the failure mode of concrete-filled fiber reinforced polymer composite tubes. Discussion is followed by closure from the authors.
Construction Applications of Fiber Reinforced Polymer Composites: A Survey
A review is made of the different applications of fiber reinforced polymer composite (FRPC) mater... more A review is made of the different applications of fiber reinforced polymer composite (FRPC) materials and carbon fiber reinforced plastic (CFRP) cables in construction. The potential FRPC application areas are classified into three groups, namely: (i) Repair and rehabilitation of structural elements using FRPC sheets, (ii) FRPC bars as a reinforcement material for concrete structural elements, and (iii) Structural elements made of FRPC. Literature relevant to FRPC material in construction is divided into the above three groups. This review focuses on experimental research only. No attempt has been made to identify different analytical studies available on FRPC. Sub-topics of the above three areas are mentioned along with partial references
FEATURE ARTICLE: Items of special interest, tutorials, and surveys: Static and Dynamic Behav Ior of Mechanical Components Associated With Electrical Transmission Lines -- Iii (a)
A semi-analytical method incorporating various displacement based formulations has been developed... more A semi-analytical method incorporating various displacement based formulations has been developed to investigate scattering of waves in composite laminated plates. Plane strain condition in composite laminated plate due to propagation of a time harmonicwave and vibrations has been investigated.Various displacement based models have been developed by using combinations of linear, quadratic, cubic and quartic variation of displacements through thickness of the lamina. Results obtained using various displacement models are compared for isotropic, orthotropic and composite laminated plates. The higher order displacement based theory using cubic variation of in-plane and transverse displacements through thickness of lamina is found to be most accurate and economical one for analyzing scattering of waves in composite laminated plates.
This study is motivated by the need to develop an efficient numerical model to simulate non-unifo... more This study is motivated by the need to develop an efficient numerical model to simulate non-uniform interfacial degradation of reinforcing steel in concrete in an accelerated corrosion setup considering the influence of differential aeration, moisture and conductivity. In this study, a multi-physics finite element (FE) model is presented to simulate spatially and temporally non-uniform surface topography of corroding steel with rust layer, and eliminates the assumption of uniform mass loss and its linear variation with time as per available literature that uses classical approach of Faraday’s law. The model is validated experimentally with accelerated corrosion setup. Unlike previous studies, pore saturation (PS) is continuously monitored and its existing experimental correlations with conductivity and oxygen diffusivity are adopted so that the model can be extended to simulate natural corrosion to enhance the accuracy of service life predictions. These evaluations can be made compl...
Analytical and numerical investigations of the flexure of isotropic plates using the novel first-order shear deformation theory
Proceedings of the Indian National Science Academy, 2021
A variant of the first-order shear deformation theory is presented for the flexure of shear defor... more A variant of the first-order shear deformation theory is presented for the flexure of shear deformable linear isotropic plates undergoing small deformations. The principle of stationary potential energy is utilized to obtain governing differential equations and variationally consistent boundary conditions. Unlike the Mindlin’s plate theory, the presented variant involves two coupled governing partial differential equations involving two unknown functions. This reduction will result in saving of the computational time involved for the plate boundary value problem, especially when external forces acting on the plate are variable/non-linear in nature. Solutions for the flexure of shear deformable isotropic plates by utilizing Levy’s method are obtained using analytical and numerical techniques. The fourth-order Runge–Kutta technique is utilized for obtaining numerical solutions. The effect of the plate thickness-to-length ratio on the flexure of shear deformable isotropic plates with two opposite edges simply-supported and remaining two edges having different combinations of boundary conditions are presented. These results are compared with corresponding results available in the literature.
Invited: Multi-model finite element approach for stress analysis of composite laminates
A multi-model global-local approach to study free edge effects in laminated composites subjected ... more A multi-model global-local approach to study free edge effects in laminated composites subjected to uniaxial in-plane loads is presented in this paper. Mixed layer-wise (LW) finite element (FE) model is used in critical free edge zone. Remaining part of plate is modelled by using higher order equivalent single layer (ESL) theory. A transition element is developed to ensure a compatibility between differently modelled subdomains. This combined model possesses traits of both ESL and LW mixed models. Higher order ESL predicts global parameters efficiently, on the other hand, mixed LW model captures the interlaminar stresses at local zones. Mixed LW model includes the transverse stresses as nodal degrees of freedom (DOF) ensuring continuity of the transverse stresses over layer interfaces without using any additional stress functions. Both, ESL and LW mixed models are developed by using three dimensional (3D) elasticity relationships and principle of minimum potential energy. The presen...
Uneven distribution of fibers can adversely affect the mechanical behavior of unidirectional comp... more Uneven distribution of fibers can adversely affect the mechanical behavior of unidirectional composites. A micromechanical model based on finite element analysis is presented to evaluate elastic and strength properties of such composites under normal loading. Analysis starts with identification of micro unit cells/micro repetitive unit cells and/or representative volume elements. Because of uneven distribution/random distribution of the fibers, fiber volume fraction can be different for different micro unit cells present at different locations in the transverse cross-section of the unidirectional composite. Configuration of the micro unit cell is worked out at the outset considering the fiber distribution having the hexagonal arrangement, but with different volume fraction at different locations. For such micro unit cells, elastic and strength properties are obtained based on finite element analysis starting with the elastic and strength properties of fiber and matrix. With the prop...
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