Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Bibliography: leaves 221-226.

Thesis (doctoral)--University of London, 1989.

This thesis describes attempts to measure the shearing strength of freshly mixed concrete and relate it to standard "Workability" tests. The study is a continuation of investigations made by Mr. Li Yang in 1963-65 at the University of British Columbia. Yang measured the shearing strength of eight mixes at one velocity and obtained a type of "viscosity" at that speed. This thesis broadens the investigation to shear strength of eight different mixes at seven different speeds. The shear box developed at the University of British Columbia and used by Mr. Yang was used in these further investigations and the shapes of the shear vs. rate of shearing strain or "viscosity" curves for eight different mixes was partially developed. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

No description available.

No description available.

No description available.

This study deals with the vibration and stability analyses of laminated plates and shells, using classical, first-order and third-order equivalent single-layer theories and the layer-wise theory of Reddy. Analytical solutions of these theories for natural frequencies and critical buckling loads of plates and shells under various boundary conditions are developed using an improved analytical procedure. A solution for the transient response of viscously damped cross-ply laminated plates, subjected to a sonic-boom type loading, is developed using the third-order shear deformation plate theory of Reddy and the first-order shear deformation plate theory. The nonlinear dynamic equations of the first-order shear deformation plate theory and the third-order shear deformation plate theory of Reddy are reformulated in terms of a pair of equations describing the interior and the edge-zone problems of rectangular plates laminated of transversely isotropic layers. The pure—shear frequencies of the plate in linear and nonlinear problems are identified from the edge—zone equation. For certain boundary conditions the original system of equations are reduced to three in number, as in the classical plate theory. The frequency and buckling equations of symmetric plates laminated of transversely isotropic layers are obtained using the Levinson’s third—order shear deformation plate theory. Using the interior and the edge—zone equations, the frequency and buckling equations are also obtained according to the first—order shear deformation plate theory. The solution contribution of the edge—zone equation is analyzed. By introducing a mixed approach, the bending problem of laminated plates with various boundary conditions is studied according to the first—order and Reddy’s third-order shear deformation plate theories. / Ph. D.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (MScEng)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The lack of a simple rational mechanical model for the shear resistance behaviour of structural concrete members results in the use of simplified empirical methods in codified shear design methods with a limited range of applicability. This may lead on the one hand to insufficient reliability for members on the boundary of the range of applicability and on the other hand to over-conservative designs. Comparison of the provision for shear resistance design of the South African code of practice for the design of concrete structures SANS 10100: 2003 with other related codes shows differences in the design variables taken into account and procedures specified to calculate shear resistance. The thesis describes a systematic evaluation of the reliability performance of the shear performance of reinforced concrete sections subjected to shear only, and in combination with flexural moments, designed with SANS 10100: 2003. Both sections with and without provision for shear reinforcement are considered. A representative range of parametric conditions are considered in the evaluation. Punching shear is not considered in the present review. Shear design as specified by SANS 10100 is compared to the provisions of the closely related British code for the structural use of concrete BS 8110, Eurocode 2 for the design of concrete structures EN 1992 and the American bridge design code AASHTO LRFD. The reliability performance of the shear design method for beams of SANS is considered in terms of a probabilistic shear resistance model, uncertainties in the basic variables such as material properties, geometry and modelling uncertainty. Modelling uncertainty is determined by comparing predicted values with published experimental results. Keywords: structural concrete; shear resistance; shear design; reliability; design codes; code companson / AFRIKAANSE OPSOMMING: Die tekortkoming van eenvoudige rasionele modelle vir skuif gedrag van strukturele gewapende beton lei tot die gebruik van vereenvoudigde empiriese metodes in gekodifiseerde skuif ontwerp met 'n beperkte omvang van gebruik. Dit mag lei tot onvoeldoende betroubaarheid vir ontwerp situasies, maar ook tot oorkonserwatiewe ontwerpe. Vergelyking van voorsienings vir skuifweerstand ontwerp in die SANS beton kode, SANS 10100: 2003 en ander verwante kodes toon verskille in ontwerp veranderings en metodes aan vir die berekening van skuifweerstand. Hierdie tesis beskryf die stelselmatige bepaling van betroubaarheids prestasie van die skuifgedrag van gewapende beton snitte ontwerp volgens SANS. Beide snitte met en sonder skuifbewapening word behandel. 'n Verteenwoordigende bestek van skuif ontwerp parameters word in ag geneem in die beoordeling van die betroubaarheid. Pons skuifword nie hier in ag geneem nie. Skuif ontwerp soos voorgeskryf deur SANS 10100 word verlyk met die ontwerp methodes van die Britse beten kode, BS 8110, die Europese beton kode, Euronorm Eurocode 2 en die Amerikaanse brug kode AASHTO LRFD. Die betroubaarheids prestasie van die skuif ontwerp metode vir SANS word bepaal deur middel van 'n probablistiese skuif ontwerp model. Modelonsekerheid is vir die doeleindes bepaal deur vergelyking met gepubliseerde eksperimentele resultate. Sleutelwoorde: strukturele beton; skuifweerstand; skuif ontwerp; betroubaarheid; ontwerp kodes; kode vergelyking.

A numerical model has been developed which simulates the three-dimensional stability and transition of a periodically forced free shear layer in an incompressible fluid. Unlike previous simulations of temporally evolving shear layers, the current simulations examine spatial stability. The spatial model accommodates features of free shear flow, observed in experiments, which in the temporal model are precluded by the assumption of streamwise periodicity; e.g., divergence of the mean flow and wave dispersion. The Navier-Stokes equations in vorticity-velocity form are integrated using a combination of numerical methods tailored to the physical problem. A spectral method is adopted in the spanwise dimension in which the flow variables, assumed to be periodic, are approximated by finite Fourier series. In complex Fourier space, the governing equations are spatially two-dimensional. Standard central finite differences are exploited in the remaining two spatial dimensions. For computational efficiency, time evolution is accomplished by a combination of implicit and explicit methods. Linear diffusion terms are advanced by an Alternating Direction Implicit/Crank-Nicolson scheme whereas the Adams-Bashforth method is applied to convection terms. Nonlinear terms are evaluated at each new time level by the pseudospectral (collocation) method. Solutions to the velocity equations, which are elliptic, are obtained iteratively by approximate factorization. The spatial model requires that inflow-outflow boundary conditions be prescribed. Inflow conditions are derived from a similarity solution for the mean inflow profile onto which periodic forcing is superimposed. Forcing functions are derived from inviscid linear stability theory. A numerical test case is selected which closely parallels a well-known physical experiment. Many of the aspects of forced shear layer behavior observed in the physical experiment are captured by the spatial simulation. These include initial linear growth of the fundamental, vorticity roll-up, fundamental saturation, eventual domination of the subharmonic, vortex pairing, emergence of streamwise vorticity, and temporary stabilization of the secondary instability. Moreover, the spatial simulation predicts the experimentally observed superlinear growth of harmonics at rates 1.5 times that of the fundamental. Superlinear growth rates suggest nonlinear resonances between fundamental and harmonic modes which are not captured by temporal simulations.