"Is it True What They Say about Models?": Modelling African American Womanhood On the Eve of the Civil Rights Era

This paper explores the work of models, modelling agencies, and popular magazines in forging a new iconography of African American womanhood. These raced and gendered images and ideas engaged heterosexual appeal, feminine deportment, and middle-class consumerist status as a strategy for race advancement on the eve of the civil rights era.Cet article explore le travail des modèles qui ont du succès, des agences de modèles, et de revues populaires en forgeant une iconographie de la féminité afro-américaine. Ces images axées sur la difference entre les races et entre les hommes et les femmes, ces idées ont engagés l'intérêt hétérosexuel, la conduite féminine, et le statut consumériste de la classe moyenne comme stratégie pour l'avancement de la race à la veille du l'époque des droits civils

Local and distortional buckling behaviour of cold-formed steel Z section beams

The economic use of cold-formed steel members means that buckling and the possible loss of effectiveness it produces are important features of design. Cross-sectional instabilities in laterally-restrained cold-formed steel beams include local and distortional buckling. The prediction of the true buckling behaviour of cold-formed steel beams accounting for all governing features such as geometrical imperfections, spread of yielding, postbuckling etc. has been possible with the development of advanced numerical modelling. In this thesis, the finite element (FE) method (ABAQUS) has been used to develop numerical analyses to study the buckling behaviour of laterally-restrained cold-formed steel lipped Z-section beams. The FE models were verified against a series of four-point bending tests available from previous research, with special references to material and geometrical nonlinearities. Two sets of analyses have been conducted: FE analyses allowing for both local and distortional buckling and ones allowing for local buckling while distortional buckling is restrained using appropriate boundary conditions. For the former, the controlling buckling mode (local, distortional or combined) at different stages of loading (up to, at and beyond maximum load) has been realized. Comparing the results of two sets of analyses, the effect of distortional buckling on performance for different geometric proportions has been studied. The effect of the lip size, flange width, angle of inclination of the edge stiffener (lip), size and position of the intermediate stiffener and material strength as well as the interaction between them on both the ultimate strength and the buckling of cold-formed Z-section beams has been investigated. Limits for optimum design of the section were proposed. Depending on the geometric properties and material strength of the section, transitions between local, distortional and combined local/distortional buckling were observed. The lip/flange interaction including the interaction between the edge stiffener (lip) and the intermediate stiffener was the key governing feature of behaviour. The effect of the linear moment gradient and sharply varying bending moment on both the ultimate strength and the buckling of cold-formed Z sections was investigated. The latter occurred in two-span continuous beams subject to uniformly distributed loading. The results of moment gradient cases were compared with those of pure bending cases. The suitability of the design treatments available in Eurocode 3 (EC3) for local, combined local/distortional and distortional buckling of cold-formed Z-section beams was assessed. Overall, the EC3 predictions for cross-sectional bending resistances were unconservative. Shortcomings were identified and some suggestions for improvements were made. This included improvements in plate buckling factors for edge-stiffened compression flanges

The weird, faded glory of black girls: De-constructing black female sexuality in the Harlem Renaissance, 1920-1930.

Focusing on the period known as the Harlem Renaissance circa 1920-1930, this study explores various forms of sexual expression open to, and opened by, black women. By defining the dominant ideology which made black female sexuality both its subject and object, this thesis examines the various ways that black women either conformed to or conflicted with dominant ideological formulae, and in doing so, approached sexual self-actualization. This study examines two art forms, literature and the blues, to demonstrate the available and varied modes in which black women expressed and defined female sexuality. My thesis proves that both female novelists and blues women played important roles in defining black female sexuality. Source: Masters Abstracts International, Volume: 37-01, page: 0100. Adviser: Christina Simmons. Thesis (M.A.)--University of Windsor (Canada), 1997

Cross-sectional optimization of cold-formed steel channels to Eurocode 3

Cold-formed steel structural systems are widely used in modern construction. However, identifying optimal cross section geometries for cold-formed steel elements is a complex problem, since the strength of these members is controlled by combinations of local, distortional, and global buckling. This paper presents a procedure to obtain optimized steel channel cross-sections for use in compression or bending. A simple lipped C-shape is taken as a starting point, but the optimization process allows for the addition of double-fold (return) lips, inclined lips and triangular web stiffeners. The cross-sections are optimized with respect to their structural capacity, determined according to the relevant Eurocode (EN1993-1-3), using genetic algorithms. All plate slenderness limit values and all limits on the relative dimensions of the cross-sectional components, set by the Eurocode, are thereby taken into account as constraints on the optimization problem. The optimization for compression is carried out for different column lengths and includes the effects of the shift of the effective centroid induced by local buckling. Detailed finite element models are used to confirm the relative gains in capacity obtained through the optimization process

Development of optimum cold-formed steel sections for maximum energy dissipation in uniaxial bending

Cold-formed steel (CFS) elements are increasingly used as load-bearing members in construction, including in seismic regions. More conventional hot-rolled steel and concrete building structures are typically allowed by the design standards to exceed their elastic limits in severe earthquakes, rendering parameters indicating ductility and energy dissipation of primordial importance. However, insufficient research has yet been conducted on the energy dissipation of CFS structures. In the majority of previous optimization research on CFS sections the ultimate capacity, as typically controlled by local, distortional and/or global buckling modes, is considered to be the sole optimization criterion. This paper aims to improve the seismic performance of CFS elements by optimising their geometric and material highly non-linear post-buckling behaviour to achieve maximum energy dissipation. A novel shape optimisation framework is presented using the Particle Swarm Optimisation (PSO) algorithm, linked to GMNIA ABAQUS finite element analyses. The relative dimensions of the cross-section, the location and number of intermediate stiffeners and the inclination of the lip stiffeners are considered to be the main design variables. All plate slenderness limit values and limits on the relative dimensions of the cross-sectional components as defined by Eurocode 3, as well as a number of practical manufacturing and construction limitations, are taken into account as constraints in the optimisation problem. It is demonstrated that a substantial improvement in energy dissipation capacity and ductility can be achieved through the proposed optimization framework. Optimized cross-sectional shapes are presented which dissipate up to 60% more energy through plastic deformations than a comparable commercially available lipped channel

Optimum design of cold-formed steel beams using Particle Swarm Optimisation method

Applying optimisation techniques to the design of cold-formed steel (CFS) sections can lead to more economical and efficient design solutions. However, a crucial factor in such an optimisation is to arrive at a solution which is practical and fits within the constraints of the fabrication and construction industries. Targeting this objective, a comprehensive investigation was conducted on the practical optimisation of CFS beams using a Particle Swarm Optimisation (PSO) method. Six different CFS channel section prototypes were selected and then optimised with respect to their flexural strength, determined according to the effective width based provisions of Eurocode 3 (EC3) part 1–3. Comparing the capacities of the optimised sections to those of the original channel sections with the same amount of structural material, significant improvements were obtained. The accuracy of the optimisation procedure was assessed using experimentally validated nonlinear Finite Element (FE) analyses accounting for the effect of imperfections. The results indicated that, using the same amount of material, the optimum sections offered up to 25% and 75% more flexural strength for laterally braced and unbraced CFS beams, respectively, while they also satisfied predefined manufacturing and design constraints. Therefore, the proposed optimisation methodology has the potential to prove useful in practical design applications