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CONTENTS
Volume 4, Number 4, August 2001
 

Abstract
The greatest suction on the cladding of flat roof low-rise buildings is known to occur beneathrnthe conical vortices that form along the roof edges for cornering winds. In a companion paper, a model ofrnthe vortex flow mechanism has been developed which can be used to connect the surface pressure beneathrnthe vortex to adjacent flow conditions. The flow model is experimentally validated in this paper usingrnsimultaneous velocity and surface pressure measurement on a 1 : 50 model of the Texas Tech Universityrnexperimental building in a wind tunnel simulated atmospheric boundary layer. Flow visualization givesrnfurther insight into the nature of peak suction events. The flow model is shown to account for the increasernin suction towards the roof corner as well as the presence of the highest suction at wind angles of 60

Key Words
wind; vortex; load; pressure; low-rise; building; flow separation.

Address
D. Banks and R. N. Meroney, Fluid Mechanics and Wind Engineering Program, Civil Engineering Department, Colorado State University, Fort Collins, CO 80523, U.S.A.

Abstract
A study of wind effects was carried out at the Boundary Layer Wind Tunnel Laboratoryrn(BLWTL) for the projected 558-m high free-standing telecommunication and observation tower for Jakarta,rnIndonesia. The objectives were to assist the designers with various aspects of wind action, including thernoverall structural loads and responses of the Tower shaft and the antenna superstructure, the local windrnpressures on components of the exterior envelope, and winds in pedestrian areas. The designers of the Towerrnare the East China Architectural Design Institute (ECADI) and PT Menara Jakarta, Indonesia. Unfortunately,rnthe project is halted due to the financial uncertainties in Indonesia. At the time of the stoppage, pilerndriving had been completed and slip forming of the concrete shaft of the Tower had begun. When completed,rnthe Tower will exceed the height of the CN-Tower in Toronto, Canada by some 5 m.

Key Words
Jakarta Tower; CN-Tower, aeroelastic model; pressure integration; Jakarta wind climate; aerodynamic response; vortex shedding; ECADI; wind tunnel; BLWTL; PT Menara Jakarta.

Address
N. Isyumov , P.C. Case and T.C.E. Ho, Boundary Layer Wind Tunnel Laboratory, The University of Western Ontario, London, Ontario, CanadarnR. Soegiarso, PT Menara Jakarta, Jakarta, Indonesia

Abstract
Presented herein is a numerical study for evaluating the aerodynamic behaviour of equippedrnbridge deck sections. In the first part, the method adopted is described, in particular concerning turbulencernmodels, meshing requirements and numerical approach. The validation of the procedure represents the aimrnof the second part of the paper: the results of the numerical simulation in case of two-dimensional, steady,rnincompressible, turbulent flow around a realistic bridge deck are compared to the data collected from wind-tunnelrntests. In order to demonstrate the influence of the section details and of the partial streamlining ofrnthe deck geometry on its aerodynamic behaviour, in the third part of the paper the effect of the fairingsrnand of each item of equipment of the section (such as central barriers, side railings and sidewalks) isrnevaluated. The study has been applied to the deck section of the Normandy cable-stayed bridge.

Key Words
computational fluid dynamic; bridge aerodynamics; section model details.

Address
L. Bruno, Department of Structural Engineering, Politecnico di Torino, Torino, ItalyrnS. Khris, OptiFlow, Consulting Company in Numerical Fluid Mechanics, Marseille, FrancernJ. Marcillat, Institut de Recherche sur les Phe nome nes Hors Equilibre, UMR 6594 UM-UP CNRS, Marseille, France

Abstract
A two dimensional discrete vortex method (DIVEX) has been developed to predict unsteadyrnand incompressible flow fields around closed bodies. The basis of the method is the discretisation of thernvorticity field, rather than the velocity field, into a series of vortex particles that are free to move in thernflow field that the particles collectively induce. This paper gives a brief description of the numericalrnimplementation of DIVEX and presents the results of calculations on a recent suspension bridge deck section.rnThe predictions for the static section demonstrate that the method captures the character of the flow fieldrnat different angles of incidence. In addition, flutter derivatives are obtained from simulations of the flowrnfield around the section undergoing vertical and torsional oscillatory motion. The subsequent predictionsrnof the critical flutter velocity compare well with those from both experiment and other computations. Arnbrief study of the effect of flow control vanes on the aeroelastic stability of the bridge is also presented and thernresults from DIVEX are shown to be in accordance with previous analytical and experimental studies. Inrnconclusion, the results indicate that DIVEX is a very useful design tool in the field of wind engineering.

Key Words
vortex method; numerical modelling; bridge aerodynamics; flutter derivatives; flow control.

Address
I.J. Taylor, Department of Mechanical Engineering, University of Strathclyde, Glasgow G1 1XJ, Scotland, U.K.rnM. Vezza, Department of Aerospace Engineering, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K.

Abstract
With respect to serviceability, antenna masts should be designed so that wind-induced motionrnwill not cause unacceptable lack of transmission for broadcasting users and wireless communication. Forrnsuch antenna masts with directional radio transmission the serviceability limit state is predominantlyrngoverned by the tolerable change of the broadcasting angle of the mounted antenna assembly andrntherefore by the tip distortion of the mast. In this paper it will be shown that refinements of the presentrnstate of design of antenna masts are possible by using the statistics of extremes applied to extreme windrnsituations and by consideration of the statistical and reliability requirements given by the operator such asrnfrequency and return period of passing the serviceability limit.

Key Words
towers; masts; antenna structures; ancillaries; directional radio transmission; serviceability limit; full-scale measurements; wind tunnel modeling; wind-induced deformation; gust response; statistics, of extremes; frequency of exceeding; design proposals.

Address
Christian Kammel, Institute of Steel Construction, Wind Engineering, RWTH Aachen, D - 52056 Aachen, Germany


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