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J.r. Banerjee - One of the best experts on this subject based on the ideXlab platform.
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modal analysis of sailplane and transport aircraft wings using the dynamic Stiffness Method
Journal of Physics: Conference Series, 2016Co-Authors: J.r. BanerjeeAbstract:The purpose of this paper is to provide theory, results, discussion and conclusions arising from an in-depth investigation on the modal behaviour of high aspect ratio aircraft wings. The illustrative examples chosen are representative of sailplane and transport airliner wings. To achieve this objective, the dynamic Stiffness Method of modal analysis is used. The wing is represented by a series of dynamic Stiffness elements of bending-torsion coupled beams which are assembled to form the overall dynamic Stiffness matrix of the complete wing. With cantilever boundary condition applied at the root, the eigenvalue problem is formulated and finally solved with the help of the Wittrick-Williams algorithm to yield the eigenvalues and eigenmodes which are essentially the natural frequencies and mode shapes of the wing. Results for wings of two sailplanes and four transport aircraft are discussed and finally some conclusions are drawn
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Linearized buckling analysis of isotropic and composite beam-columns by Carrera Unified Formulation and dynamic Stiffness Method
Mechanics of Advanced Materials and Structures, 2016Co-Authors: Erasmo Carrera, Alfonso Pagani, J.r. BanerjeeAbstract:AbstractThis article introduces a one-dimensional (1D) higher-order exact formulation for linearized buckling analysis of beam-columns. The Carrera Unified Formulation (CUF) is utilized and the displacement field is expressed as a generic N-order expansion of the generalized unknown displacement field. The principle of virtual displacements is invoked along with CUF to derive the governing equations and the associated natural boundary conditions in terms of fundamental nuclei, which can be systematically expanded according to N by exploiting an extensive index notation. After the closed form solution of the N-order beam-column element is sought, an exact dynamic Stiffness (DS) matrix is derived by relating the amplitudes of the loads to those of the responses. The global DS matrix is finally processed through the application of the Wittrick-Williams algorithm to extract the buckling loads of the structure. Isotropic solid and thin-walled cross-section beams as well as laminated composite structures are an...
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free vibration analysis for plates with arbitrary boundary conditions using a novel spectral dynamic Stiffness Method
Computers & Structures, 2016Co-Authors: Xiang Liu, J.r. BanerjeeAbstract:Exact Method for modal analysis of plates with arbitrary boundary conditions.Enhancement of the Wittrick-Williams algorithm by resolving the J0 count elegantly.Securing exact solutions for free vibration of plates for benchmark purposes.The Method has two orders of magnitude higher computational efficiency than the FEM.Discussion and conclusions on a wide range of existing analytical and exact Methods. An exact Method for free vibration analysis of plates with arbitrary boundary conditions is presented. This is achieved by integrating the spectral Method into the classical dynamic Stiffness Method. The formulation satisfies the governing differential equation exactly and any arbitrary boundary conditions are satisfied in a series sense. The Wittrick-Williams algorithm is enhanced with several elegant techniques to obtain solutions. The exactness and computational efficiency of the Method are demonstrated by comparing results obtained from other Methods. Finally, mathematical and physical insights are gained and significant conclusions are drawn for various analytical Methods for free vibration analysis of plates.
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an exact spectral dynamic Stiffness Method for free flexural vibration analysis of orthotropic composite plate assemblies part i theory
Composite Structures, 2015Co-Authors: Xiang Liu, J.r. BanerjeeAbstract:An exact spectral-dynamic Stiffness Method (S-DSM) for free vibration analysis of composite plates and plate assemblies has been proposed in Part I of this two-part paper. The main purpose of this Part II paper is twofold: (i) To validate and demonstrate the superiority of the proposed S-DSM and (ii) To establish exact benchmark solutions for free vibration of composite plate-like structures. The S-DSM is applied to a number of problems covering orthotropic composite plates and plate assemblies. It is demonstrated that the S-DSM gives exact solutions with high computational efficiency within low as well as high frequency ranges. The applications are completely general and the new development can handle complex plate shapes with any boundary conditions.
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development of dynamic Stiffness Method for free vibration of functionally graded timoshenko beams
Computers & Structures, 2015Co-Authors: J.r. BanerjeeAbstract:The free vibration of functionally graded Timoshenko beams is investigated by developing the dynamic Stiffness Method. Material properties of the beam are assumed to vary continuously in the thickness direction. The governing differential equations of motion are solved and expressions for axial force, shear force and bending moment are derived. The dynamic Stiffness matrix is then formulated by relating the amplitudes of forces and displacements at the ends of the beam. The Wittrick-Williams algorithm is used as solution technique to yield the natural frequencies and mode shapes of some illustrative examples. The results are discussed and some conclusions are drawn.
Ravi P Prakash - One of the best experts on this subject based on the ideXlab platform.
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distributed plasticity model for analysis of steel structures subjected to fire using the direct Stiffness Method
Fire Safety Journal, 2019Co-Authors: Ravi P Prakash, Gaurav SrivastavaAbstract:Abstract This article develops a temperature-dependent distributed plasticity model in a direct Stiffness Method (DSM) based formulation for coupled nonlinear thermo-mechanical analysis of steel space frames. The developed framework considers geometric and material nonlinearities, and performs coupled thermo-mechanical analysis by a two-level spatial discretization strategy. An isotropic hardening plasticity in combination with the von Mises yield criterion is considered, where the temperature-dependent yield function is derived from the stress-strain relations of Eurocode 3. The effects permanent plastic strains, large deformations and temperature-dependent material properties are directly incorporated in to the force deformation relations derived in a DSM based setting. Such a DSM based framework in conjunction with the distributed plasticity model facilitates higher computational efficiency. To ensure full coupling between mechanical and thermal solvers, thermodynamically consistent plastic heating term is added to the energy balance of the system. Also, connection flexibility is accounted for by developing a zero-length spring element integrated with 1-D beam-column elements. Five numerical examples are presented to demonstrate the efficacy of the developed framework. Within the numerical investigation, the importance of plastic heating coupling in the context of macro modelling based structural fire analysis of steel structures is quantified and the results indicate that such a coupling can be ignored in such macro scale structural fire computations.
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fully coupled multi physics nonlinear analysis of structural space frames subjected to fire using the direct Stiffness Method
Advances in Structural Engineering, 2018Co-Authors: Ravi P Prakash, Gaurav SrivastavaAbstract:This article develops a fully coupled hydro-thermo-mechanical formulation based on the direct Stiffness Method for analysis of steel and reinforced concrete structural space frames. The superiority...
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nonlinear analysis of reinforced concrete plane frames exposed to fire using direct Stiffness Method
Advances in Structural Engineering, 2018Co-Authors: Ravi P Prakash, Gaurav SrivastavaAbstract:This article presents a framework based on the direct Stiffness Method for nonlinear thermo-mechanical analysis of reinforced concrete plane frames subjected to fire. It accounts for geometric nonl...
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an integrated framework for nonlinear analysis of plane frames exposed to fire using the direct Stiffness Method
Computers & Structures, 2017Co-Authors: Gaurav Srivastava, Ravi P PrakashAbstract:Abstract A novel coupled framework for analysis of reinforced concrete (RC) and steel planar frames subjected to fire is developed with three-way coupling between heat transfer, mechanical deformations and pore pressure build-up. Structural members are discretized in space using a two-level scheme where the mechanical solver utilizes 1D line elements, and the thermal and the pore pressure solvers work on 2D finite element (FE) meshes for each sub-span used by the mechanical solver. Such a strategy enables consideration of effects of large deformations, temperature-dependent material properties (thermal, moisture transport and mechanical), and spalling. None of the earlier developed frameworks considered a three-way coupling between mechanical, thermal and pore pressure solvers without employing a full-fledged 3D FE scheme. A matrix Method type approach, developed herein, enables modeling of the three main physical processes taking place in RC members during fire without the need to consider full-fidelity 3D FEM. Several numerical examples are presented to demonstrate the accuracy and applicability of the developed framework in fire analysis of normal and high strength RC and steel structures.
Gaurav Srivastava - One of the best experts on this subject based on the ideXlab platform.
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distributed plasticity model for analysis of steel structures subjected to fire using the direct Stiffness Method
Fire Safety Journal, 2019Co-Authors: Ravi P Prakash, Gaurav SrivastavaAbstract:Abstract This article develops a temperature-dependent distributed plasticity model in a direct Stiffness Method (DSM) based formulation for coupled nonlinear thermo-mechanical analysis of steel space frames. The developed framework considers geometric and material nonlinearities, and performs coupled thermo-mechanical analysis by a two-level spatial discretization strategy. An isotropic hardening plasticity in combination with the von Mises yield criterion is considered, where the temperature-dependent yield function is derived from the stress-strain relations of Eurocode 3. The effects permanent plastic strains, large deformations and temperature-dependent material properties are directly incorporated in to the force deformation relations derived in a DSM based setting. Such a DSM based framework in conjunction with the distributed plasticity model facilitates higher computational efficiency. To ensure full coupling between mechanical and thermal solvers, thermodynamically consistent plastic heating term is added to the energy balance of the system. Also, connection flexibility is accounted for by developing a zero-length spring element integrated with 1-D beam-column elements. Five numerical examples are presented to demonstrate the efficacy of the developed framework. Within the numerical investigation, the importance of plastic heating coupling in the context of macro modelling based structural fire analysis of steel structures is quantified and the results indicate that such a coupling can be ignored in such macro scale structural fire computations.
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fully coupled multi physics nonlinear analysis of structural space frames subjected to fire using the direct Stiffness Method
Advances in Structural Engineering, 2018Co-Authors: Ravi P Prakash, Gaurav SrivastavaAbstract:This article develops a fully coupled hydro-thermo-mechanical formulation based on the direct Stiffness Method for analysis of steel and reinforced concrete structural space frames. The superiority...
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nonlinear analysis of reinforced concrete plane frames exposed to fire using direct Stiffness Method
Advances in Structural Engineering, 2018Co-Authors: Ravi P Prakash, Gaurav SrivastavaAbstract:This article presents a framework based on the direct Stiffness Method for nonlinear thermo-mechanical analysis of reinforced concrete plane frames subjected to fire. It accounts for geometric nonl...
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an integrated framework for nonlinear analysis of plane frames exposed to fire using the direct Stiffness Method
Computers & Structures, 2017Co-Authors: Gaurav Srivastava, Ravi P PrakashAbstract:Abstract A novel coupled framework for analysis of reinforced concrete (RC) and steel planar frames subjected to fire is developed with three-way coupling between heat transfer, mechanical deformations and pore pressure build-up. Structural members are discretized in space using a two-level scheme where the mechanical solver utilizes 1D line elements, and the thermal and the pore pressure solvers work on 2D finite element (FE) meshes for each sub-span used by the mechanical solver. Such a strategy enables consideration of effects of large deformations, temperature-dependent material properties (thermal, moisture transport and mechanical), and spalling. None of the earlier developed frameworks considered a three-way coupling between mechanical, thermal and pore pressure solvers without employing a full-fledged 3D FE scheme. A matrix Method type approach, developed herein, enables modeling of the three main physical processes taking place in RC members during fire without the need to consider full-fidelity 3D FEM. Several numerical examples are presented to demonstrate the accuracy and applicability of the developed framework in fire analysis of normal and high strength RC and steel structures.
Jianwen Liang - One of the best experts on this subject based on the ideXlab platform.
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fundamental solutions of a multi layered transversely isotropic saturated half space subjected to moving point forces and pore pressure
Engineering Analysis With Boundary Elements, 2017Co-Authors: Jianwen LiangAbstract:Abstract The steady-state dynamic response of a multi-layered transversely isotropic (TI) saturated half-space due to point forces and pore pressure moving with a constant speed is investigated in this paper. To solve this problem, the dynamic Stiffness Method combined with the inverse Fourier transform is employed. First, the governing equations in terms of the displacement components and pore fluid pressure are solved in the transformed domain by employing the Fourier transform. Next, the exact three-dimensional (3D) dynamic Stiffness matrices for the TI saturated layer, as well as the TI saturated half-space, are constructed, and the global dynamic matrix of the problem is formulated by assembling the dynamic matrices of the discrete layers and the underlying half-space. Finally, solutions in the frequency-wavenumber domain of the displacement, pore pressure and stress are obtained through the dynamic Stiffness Method. The result in the time-space domain is recovered by the Fourier synthesis of the frequency responses which, in turn, are obtained by numerical integration over on one horizontal wavenumber. The accuracy of the developed formulations is confirmed by comparison with existing solutions for an isotropic and saturated medium that is a special case of the more general problem addressed. Numerical results for both low and high source velocities are presented, and the effects of moving speed, material anisotropy, permeability, surface drainage condition and TI saturated layer on the dynamic response are analyzed. It is observed that the dynamic responses reach their peak values when the source velocity is equal to or approaches the phase velocities of SH-, qP1-, qP2- and qSV- in the horizontal direction and the phase velocity of qRayleigh waves. Material anisotropy is very important for the accurate assessment of the dynamic response due to the moving point forces and pore pressure in a TI saturated medium.
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3D dynamic response of a multi-layered transversely isotropic half-space subjected to a moving point load along a horizontal straight line with constant speed
International Journal of Solids and Structures, 2016Co-Authors: Zhenning Ba, Jianwen Liang, Hang JiAbstract:Abstract The steady-state dynamic response of a multi-layered transversely isotropic (TI) half-space generated by a point load moving along a horizontal straight line with constant speed is investigated in this paper. To solve this problem, the direct Stiffness Method combined with the inverse Fourier transform is employed. First, the dynamic equilibrium equations for the TI medium are solved in the frequency and wavenumber domains and the exact three-dimensional (3D) dynamic Stiffness matrix for the layered TI half-space is established. Then, the solution in the frequency and wavenumber domains is obtained through the direct Stiffness Method. Finally, the dynamic response in the time and space domains is obtained using the double inverse Fourier transform with respect to the frequency and one horizontal wavenumber. The accuracy of the Method is verified through comparisons with the results for the limiting isotropic case ( de Barros and Luco, 1994 ) as well as the results for the non-moving 3D point load being applied in a multi-layered TI half-space ( Khojasteh et al., 2011 ). Numerical results for both the uniform TI half-space and multi-layered TI half-space are presented, and the effects of the moving speed and especially the material anisotropy on the dynamic response are analyzed. Numerical results show that the dynamic response in a TI medium can be significantly different from that in an isotropic medium, and material anisotropy is very important for the accurate assessment of the dynamic response due to a point load moving in a TI half-space.
Richard J. Bathurst - One of the best experts on this subject based on the ideXlab platform.
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Design and Performance of 6.3-m-High, Block-Faced Geogrid Wall Designed Using K-Stiffness Method
Journal of Geotechnical and Geoenvironmental Engineering, 2014Co-Authors: Tony M. Allen, Richard J. BathurstAbstract:AbstractA high-density polyethylene (HDPE) geogrid soil-reinforced dry-cast concrete block retaining wall 6.3-m high was designed using the K-Stiffness Method as part of a highway-widening project southeast of Seattle, Washington. The amount of reinforcement needed for the original wall design using the K-Stiffness Method was approximately 50% of that required using the AASHTO simplified Method. This paper describes the construction, instrumentation program, and interpretation of the measurements. Geogrid strains were measured using strain gauges and extensometers attached to reinforcement layers. An extensive materials testing program was conducted to characterize the backfill soil properties and geogrid Stiffness properties and to calibrate strain gauge readings. The reinforcement loads deduced from the measured strains are compared with Class A, B, and C1 predictions using the AASHTO simplified and K-Stiffness Methods. These comparisons demonstrate that the simplified Method significantly overestimated...
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refinement of k Stiffness Method for geosynthetic reinforced soil walls
Geosynthetics International, 2008Co-Authors: Richard J. Bathurst, Axel Nernheim, Yoshihisa Miyata, A M AllenAbstract:The K-Stiffness Method is an empirically-developed working stress Method used to compute reinforcement loads for the internal stability design of geosynthetic-reinforced soil walls under serviceabi...
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development of the k Stiffness Method for geosynthetic reinforced soil walls constructed with c ϕ soils
Canadian Geotechnical Journal, 2007Co-Authors: Yoshihisa Miyata, Richard J. BathurstAbstract:In this paper the K-Stiffness Method is extended to the case of c-ϕ soils using data obtained from a total of nine new case studies – six from Japan and three from the USA. A common feature in this new data set is that the walls were all constructed with a vertical face using backfill soils with a range of fines content. The walls varied widely with respect to facing type. This new data set together with previously published data for vertical walls is now used to isolate the effect of soil cohesion on reinforcement loads within the framework of the original K-Stiffness Method. The new data set is used to calibrate a modified K-Stiffness Method equation that includes a cohesion influence factor. The modified K-Stiffness Method is demonstrated to quantitatively improve the estimate of the magnitude and distribution of reinforcement loads for internal stability design of vertical-faced geosynthetic reinforced soil walls with c-ϕ soil backfills when compared to the current American Association of State Highwa...
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evaluation of k Stiffness Method for vertical geosynthetic reinforced granular soil walls in japan
Soils and Foundations, 2007Co-Authors: Yoshihisa Miyata, Richard J. BathurstAbstract:In this paper the K-Stiffness Method as originally proposed by Allen et al. (2003) is re-examined using a total of six new case studies-five from Japan and one from the USA. A common feature of the walls in this new data set is that the walls were all constructed with a vertical face and a granular backfill. However, the walls varied widely with respect to facing type. This new data set together with data for vertical walls previously published by Allen and Bathurst (2002a,b) and Allen et al. (2002) is now used to isolate the effect of the facing Stiffness factor on reinforcement loads and to adjust the original equation that was developed to calculate its value. The paper also shows that predicted reinforcement loads using the current AASHTO Simplified Method in the USA and the current PWRC Method in Japan give the same reinforcement load predictions, and both grossly over-estimate the values deduced from measured strains. The new data set is used to slightly refine the estimate of the facing Stiffness factor used in the original K-Stiffness Method. The original and modified K-Stiffness Method are demonstrated to quantitatively improve the estimate of the magnitude and distribution of reinforcement loads for internal stability design of vertical-faced geosynthetic reinforced soils walls with granular backfills when compared to the current American and Japanese Methods.