Dear members,
I am looking for the following papers:
A Numerical Study of Wind Loads on Large Highway Sign Structures
Authors:
George Constantinescu ; Asghar Bhatti ; and Talia Tokyay
Abstract:
Accurate estimation of wind forces on large highway sign structures is important due to possible structural failure of these sign structures under strong winds. The use of large panels for the traffic signs is increasingly more common as we attempt to better manage the highway traffic flow and automate the highway systems. In order to be able to predict behavior of these structures, accurate knowledge of the forces on these structures must be known. An important aspect of wind loads on highway structures that is generally not appreciated is the effect of interactions among the panel structures on these forces. The main objective of the proposed study is to use Computational Fluid Dynamics (CFD) tools to determine the wind loads and pressure distributions by accurate numerical simulations of the air flow characteristics around large highway sign structures under severe wind speeds conditions. The pressure distributions are needed in case a detailed structural dynamics analysis will be performed. In particular, the present study investigates the effect induced by the presence of back-to-back signs.
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Masood Hajali ; and Caesar Abishdid
Abstract:
The dynamic properties of the cantilever sign structures such as its mode shapes and frequency for different modes are being studied under wind load. The analysis considered the dead loads of the structure principally the self-weight of the truss, sign, and walkways, and the wind load. Finite element analysis are conducted to evaluate the modal stresses in the truss and compared to the total stresses. The first three mode shapes in the wind load direction and the gravity load direction are modeled. The modal participating mass ratios of the sign structure for different mode shapes are also calculated. Results show that in chord members with 24 inch length, 50 percent and in chord members with 48 inch length, almost all the stresses (bending + axial) are modal stresses. In interior diagonal members 40 percent, in horizontal diagonal members 75 percent and in column part almost 75 percent of stresses (bending + axial) are modal stresses. The purpose of the study is a modal and static analysis in critical members of a cantilever sign structure under wind loading using finite element method.
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Attilio Iannuzzi and Paolo Spinelli
Abstract:
With modern computational means, the use of deterministic methods to predict the aerodynamic behavior of structures is becoming an attractive alternative to frequency domain methods. Wind speed samples can be generated by various techniques and fed into the system's equations of motion. The use of deterministic approaches, however, requires the artificial wind to be realistic and the simulation technique efficient. A study is undertaken to investigate the merits and drawbacks of commonly used simulation techniques. The latter can be divided into two classes, i.e., wave superposition methods and methods based on linear filtering. Techniques for simulating single and multiple time series are reviewed. Artificial wind speed is generated, and the respective responses calculated. The effects on the response of the simulated samples' different statistical properties are investigated. Results show that dynamic response is affected by the intrinsic characteristics of simulated fluctuations and their degree of correlation. Linear filters are computationally more advantageous and, in general, lead to larger response parameters compared with wave superposition methods. The use of autoregressive‐type simulation methods is recommended.
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Y. C. Park; S. Roy; R. Sause; and J. W. Fisher
Abstract:
Over the past two decades fatigue failure of cantilevered highway sign and traffic signal structures are increasingly being reported around the United States, primarily due to wind induced oscillations. For aesthetic reasons many of these structures are built with multisided tubular sections with sharp corners. Fatigue performance of fillet-welded tube-to-end plate connections in multi-sided sign/signal structures were evaluated by laboratory testing and parametric finite element analyses (FEA). Seven full size galvanized sign/signal structure specimens having eight sided cross section were fatigue tested under constant amplitude loading simulating wind induced aero-elastic galloping oscillation. Fatigue cracking in multi-sided sections mostly initiate at the bend corners of tube-to-end plate welded connection, and may appear early in service. Flexibility of the end plate, the number of sides, and the corner bend radius are the important parameters that affect fatigue resistance of multi-sided tubular structures. The existing specification does not address the effects of the connection geometry on their fatigue design. The experimental and analytical studies established the fatigue design provisions of tube-to-end plate connections in multi-sided sign and signal structures.
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regards,
apocalipse
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