The paper presents a numerical evaluation of various reinforced concrete structural systems with reference to their response to gravity and wind loads. The structural systems considered are multistory cast-in-place, precast and mixed precast and in-situ skeletons with and without shear walls employed in current building practice. The results of static, dynamic, and stability FE-analyses of such systems are discussed. Cast-in-place and mixed skeletons are shown to be efficient loadbearing systems for multistory residential and office buildings.

     The properties of symmetry of turbulent boundary layer flows are studied utilizing the Lie group theory. The self-similar forms of the independent variables and the solution functions for the boundary-layer type flows for four models of turbulent viscosity are obtained. The developed approach of finding a self-similar transformation for turbulent boundary-layer problems makes it possible to obtain numerical and simplified analytical solutions for a number of important flow situations.

     In this study, an elastic-plastic stress analysis is carried out on symmetric steel fiber reinforced high density polyethylene thermoplastic matrix laminated beams under a bending moment. The Bernoulli-Euler theory is used. The orientation angles are chosen as (90^o/0^o)₂, (30^o/-30^o)₂, (45^o/-45^o)₂ and (60^o/-60^o)₂. The composite material is assumed to be linearly hardening. The stress component 'sigma'_x is to be maximum at the upper and lower surfaces in the elastic-plastic solution. The residual stress component 'sigma'_x is found to be highest at the upper and lower surfaces. However, when the plastic region is further expanded the residual stress component 'sigma'_x is found to be the highest at the elastic and plastic boundaries. The plastic flow is to be maximum at the upper and lower surfaces for the (30^o/-30^o)₂ orientation. The transverse displacement is obtained to be highest at the free end for the (90^o/0^o)₂ orientation.

     The viscoelastic core of a line vortex embedded in a radially inward axisymmetric stagnation point flow for a Maxwell fluid and an Oldroyd B fluid is considered. Velocity, vorticity and stress distributions are calculated and compared with those of the Newtonian fluid. It is found that there are pronounced effects of viscoelastic properties on these distributions with respect to those of the Newtonian fluid.

     Water wave scattering by two thin symmetric plates submerged in water of uniform finite depth is investigated here assuming the linear theory. The problem is formulated in terms of two hypersingular integral equations involving the discontinuities in the symmetric and antisymmetric potential functions describing the motion in the fluid, across one of the plates. These are solved approximately by an expansion-cum-collocation method in which the unknown discontinuities across a plate are approximated by a finite series involving Chebyshev polynomials of the second kind. The reflection and transmission coefficients are then obtained numerically. The numerical results for the reflection coefficient are depicted graphically against the wave number for different configurations of the plates. It is observed that if the depth of submergence of the mid points of the plates below the free surface is of the order of one-tenth of the depth of the water bottom, then the deep water results effectively hold good. Also known results for two thin vertical plates, a single vertical plate are recovered as special cases.

     In this paper, we present a boundary integral method in order to determine the oscillatory Stokes flow due to translational or rotational oscillations of a solid particle in an unbounded viscous incompressible fluid. As an application of this method, we study both cases of small-and high-frequency oscillations. Finally, we give some numerical results in the case of transverse oscillations of a prolate spheroid.

     The steady state response of a micropolar elastic solid with an overlying semi-infinite thermal conducting fluid subjected at the plane interface to a moving point load is determined. The analytic expressions of displacement components, force stress, couple stress and temperature distribution are obtained in the physical domain for Lord-Shulman (L-S), Green-Lindsay (G-L), coupled theory (C-T) and Green-Naghdi (G-N) theories of thermoelasticity by the use of Fourier transform technique and are shown graphically for magnesium crystal like material. The integral transform has been inverted by using a numerical technique.

     The disturbance due to a time harmonic mechanical, horizontal or vertical and thermal source in a homogeneous, thermally conducting cubic crystal, elastic half-plane is investigated by applying the Fourier transform. The displacements, stresses and temperature distribution so obtained in the physical domain are computed numerically and illustrated graphically. The numerical results of these quantities for magnesium crystal-like material are illustrated to compare the results for different theories of generalized thermoelasticity for insulated boundary and temperature gradient boundary.

     In this paper, a generalized FE formulation for buckling analysis of nonprismatic columns with various cross-sections is established by using the Chebyshev polynomial approach to the governing differential equation. The proposed formulation includes the effects of shear deformation and is therefore applicable to solid or built-up columns. The change of the sectional properties along the length direction, such as the area and inertia moment, need not be fitted with approximate expressions and can be defined exactly and freely with user-defined functions in programming. Buckling of the three structures, respectively for a tapered mast column with a circular hollow section, a web-tapered I-sectional column and a tapered lattice column, is studied numerically and compared with the results of previous studies. The effects of shear deformation on the buckling loads of those tapered columns are specified.

     In recent years there has been a considerable theoretical and experimental interest in a laser driven ablative surface in inertial fusion energy (IFE). The existing studies of nonuniformities will not prevent the surface instabilities which originate at the ablation surface due to acceleration of high density plasma by low density plasma, known as the Rayleigh-Taylor instability (RTI). The present work is aimed at controlling the growth rate of RTI in a laser irradiated porous target (that is a hollow target filled with a porous material) at moderate intensities. This RTI has been studied using the moment method. The dispersion relation is obtained in terms of Bond number B connected with the surface tension and the modified Reynolds number R. This dispersion relation is computed for different values of B, R and several particular cases for long and short wave length perturbation and the results are depicted graphically. It is shown that the permeability of the porous region scaled with the Reynolds number decreases considerably the growth rate of RTI compared to that of a hollow shell.

     Linear and non-linear analyses of convection in a second-order Boussinesquian fluid-saturated porous medium are made. The Rivlin-Ericksen constitutive equation is considered to effect a viscoelastic correction to the Brinkman momentum equation together with a single-phase heat transport equation. The linear and non-linear analyses are respectively based on the normal mode technique and the truncated representation of Fourier series. The linear theory reveals that the critical eigenvalue is independent of viscoelastic effects and the principle of exchange of stabilities holds. The non-linear study of cellular convection leads to an autonomous system of differential equations which is solved numerically. The finite amplitude disturbances are found to be independent of transient conditions and viscoelasticity is shown to stabilize the system. The Nusselt number is calculated for different values of the parameters arising in the problem. The possibility of chaotic motion and its similarity to the problem of magnetoconvection are discussed.

     The stability of two superposed couple-stress fluids of uniform densities, permeated with suspended particles, in a porous medium is considered. A stability analysis is carried out and for mathematical simplicity we consider two highly viscous fluids of equal kinematic viscosities and equal couple-stress kinematic viscosities. The system is found to be stable for a potentially stable configuration under certain condition whereas a potentially unstable configuration remains unstable for the couple-stress fluid permeated with suspended particles in a porous medium. The growth rates of perturbation are found to be both increasing (for some wave numbers) and decreasing (for other wave numbers) with the increase in medium permeability.

     The paper presents a model for investigating structural vibrations in rolling element bearings. The mathematical formulation accounted for tangential motions of rolling elements as well as inner and outer races with the sources of nonlinearity such as the Hertzian contact force, surface waviness and internal radial clearance transition resulting from no contact to contact state between rolling elements and the races. The contacts between the rollers and races are treated as nonlinear springs and the springs act only in compression to simulate the contact deformation and resulting force. The nonlinear stiffness is obtained by using the equations for the Hertzian elastic contact deformation theory. As the nonlinear bearing forces act on the system, a new reduction method and corresponding integration technique is proposed to increase the numerical stability and decrease computer time for system analysis. The effects of various defects of a rotor bearing system in which the rolling element bearings show the periodic, quasi-periodic and chaotic behavior are analyzed. Poincare maps and Fourier spectra are used to elucidate and to illustrate the diversity of the system behavior. It is shown that due to defects such as surface waviness and internal radial clearance the system exhibits an undesirable jump phenomenon with quasi-periodic, subharmonic and chaotic motions.