Large-Scale Testing to Study the Effects of Critical Parameters on the Aerodynamic Behavior of Long Span Bridges

Long-span bridges are flexible and therefore are sensitive to wind induced effects. One way to improve the stability of long span bridges against flutter is to use cross-sections that involve twin side-by-side decks. However, this can amplify responses due to vortex induced oscillations. Wind tunnel testing is a well-established practice to evaluate the stability of bridges against wind loads. In order to study the response of the prototype in laboratory, dynamic similarity requirements should be satisfied. One of the parameters that is normally violated in wind tunnel testing is Reynolds number. In this dissertation, the effects of Reynolds number on the aerodynamics of a double deck bridge were evaluated by measuring fluctuating forces on a motionless sectional model of a bridge at different wind speeds representing different Reynolds regimes. Also, the efficacy of vortex mitigation devices was evaluated at different Reynolds number regimes. One other parameter that is frequently ignored in wind tunnel studies is the correct simulation of turbulence characteristics. Due to the difficulties in simulating flow with large turbulence length scale on a sectional model, wind tunnel tests are often performed in smooth flow as a conservative approach. The validity of simplifying assumptions in calculation of buffeting loads, as the direct impact of turbulence, needs to be verified for twin deck bridges. The effects of turbulence characteristics were investigated by testing sectional models of a twin deck bridge under two different turbulent flow conditions. Not only the flow properties play an important role on the aerodynamic response of the bridge, but also the geometry of the cross section shape is expected to have significant effects. In this dissertation, the effects of deck details, such as width of the gap between the twin decks, and traffic barriers on the aerodynamic characteristics of a twin deck bridge were investigated, particularly on the vortex shedding forces with the aim of clarifying how these shape details can alter the wind induced responses. Finally, a summary of the issues that are involved in designing a dynamic test rig for high Reynolds number tests is given, using the studied cross section as an example.

Love comes in at the eye

LOVE COMES IN AT THE EYE relates the story of Marshall Craig, a Midwesterner transplanted to South Florida who turns 35 in the course of the book. Marshall is an assistant curator for a Miami art museum, a man who has been obsessed with--as he calls it--a greed for seeing from a young age. His fascination with the surface of appearance of things is exacerbated by his precocious studies in art and its histories. Marshall views himself as marked by his red hair and freckled skin, as someone whose chances of attracting a partner into a meaningful relationship have been diminished by his looks. He is colored by his image of himself as unattractive and most importantly, convinced that his romantic life would be more successful, more vibrant, if he'd been graced with the face and figure of, say, a Velazquez. When Marshall meets a Cuban-born man from Atlanta, he is transfixed by the conviction that this is the man the universe has selected for him. The thrust of the story goes beyond boy-meets/loses/gets-boy to an exploration of said boy coming to terms with his definition of self. In a pivotal span of six months, the book explores Marshall's obsessions with seeing and how they define his vision of reality, the emphasis placed on beauty in gay culture, the tentative beginnings of a relationship as it takes root and grows, and finally, the inexplicable, magical forces that direct our romantic destinies.