Wind Loading Handbook for Australia and New Zealand: background to AS/NZS1170.2 wind actions

Recent wind events in Australia and overseas have caused catastrophic results in those affected areas, with deaths being reported as well as widespread destruction. Research and information gathered from these events have been incorporated into the latest edition of AS/NZS 1170.2-2011 to now represent a more realistic determination of wind actions. The Standard applies to structures ranging from 'the less sensitive to wind action to those for which dynamic response must be taken into consideration'. This handbook was prepared by the AWES to provide background information into wind and its actions, but also into the derivation of the Standard and its contents. It covers items such as: • Nature of wind loading • Wind speeds and multipliers • Shape factors for structures • Dynamic response In particular, it equips users with a better understanding of wind and the Standard to provide them with improved interpretation and judgment in determining wind actions on structures. Equally important, it enables the user to extend the Standard limitations while still complying with regulations, albeit other information may be necessary

Aerodynamic performance of twin-box decks: a parametric study on gap width effects based on validated 2D URANS simulations

[Abstract:] 2D URANS simulations are conducted aiming to study the aerodynamic performance under smooth flow of twin-box decks depending on the gap distance between girders. The Stonecutters Bridge is taken as the reference geometry. In this parametric study, 14 gap to depth ratios in the range 0 ≤ G/D ≤ 9.70 are investigated, and for each geometry, 11 angles of attack in the range −10 ◦ ≤ α ≤ 10 ◦ are considered. Specific goals of this research have been: identification of the fundamental flow features, study of mean and fluctuating pressure coefficients distributions, identification of the vortex shedding mechanisms and general aerodynamic characterisation based on force coefficients. The numerical results provided herein are validated with wind tunnel data previously reported in the literature, finding a good agreement. A critical gap to depth ratio at G/D = 2.35, in terms of aerodynamic response, was identified, which is consistent with the value reported in the literature for a different bridge based on wind tunnel tests. The obtained set of data provide a general picture of the expected aerodynamic performance of a twin-box deck depending on the gap distance and could be of great value at the early design stage of long-span cable-supported bridges.Ministerio de Economía y Competitividad; BIA2016-76656-RMinisterio de Economía y Competitividad; BES-2014-068418Ministerio de Economía y Competitividad; BIA2013-41965-PXunta de Galicia; ED431C 2017/7

Square Cylinder Under Different Turbulent Intensity Conditions by Means of Small-Scale Turbulence

[Abstract] The phenomenon of turbulence is present in almost every type of flow in practical applications. Depending on its level of intensity and length scale, it can modify both the aerodynamic and aeroelastic performance of a body under flow action. In wind tunnel tests, the desired turbulence level is achieved by placing obstacles, spires, grids and extra roughness generators upwind the tested model. On the other hand, when trying to reproduce turbulence effects by means of a computational fluid dynamics (CFD) approach, two options have usually been considered: synthetic turbulence generation and the reproduction of velocity and pressure fluctuations recorded from previous simulations or wind tunnel tests. Another option, whose feasibility in CFD applications is addressed in this work by means of a 2D URANS (unsteady Reynolds averaged Navier–Stokes) consists of placing a rod upstream of the studied body, near the stagnation line. This approach is based on the generation of small scale turbulence upstream of the studied body, so that the turbulent wake generated by an upwind rod impinges on the body located downwind. In the present study, by means of 2D URANS simulations, the smooth flow over a circular cylinder (the upwind rod) is studied focusing on its wake turbulence characteristics. Furthermore, the aerodynamic performance of a square cylinder, first under smooth flow, and later immersed in the turbulent wake of the upstream rod, are analysed. A substantial effort has been devoted in the verification studies of the numerical models. It has been found that the adopted numerical approach is able to reproduce the turbulent characteristics of the rod wake and assess the impact of the turbulent flow on a square cylinder, providing a promising agreement with experimental data.Xunta de Galicia; ED431C2017/7

Wind tunnel study of pedestrian level wind environment around tall buildings: Effects of building dimensions, separation and podium

It is well known that high-rise buildings affect the surrounding pedestrian level wind environment. In recent years, awareness and concern has increased about the creation of low wind speed areas around tall buildings which may lead to poor out-door air ventilation. In addition, new building developments are often not restricted to a single building, but comprise a row of buildings, which may have complex plan-forms, and some integrating an extensive podium. This paper aims at providing a fundamental understanding of wind-structure interactions that govern the effects of building dimensions and separations, a row of buildings and podium on the pedestrian level wind environment, for both weak and strong wind conditions, by a series of parametric wind tunnel studies. The study area covered an extensive area which covered up to 400 m downstream of the test buildings. The results show that a single wider building created adverse effects on the natural air ventilation at pedestrian level around the building while a taller building improved the near-field air ventilation conditions. In the studies of building separation effects, the results show an adverse effect on natural air ventilation at pedestrian level when the building separations are less than half the building width. Inclusion of a podium was also found to adversely affect the air movement around buildings. © 2011 Elsevier Ltd

Wind Loading Handbook for Australia and New Zealand: background to AS/NZS1170.2 wind actions

Recent wind events in Australia and overseas have caused catastrophic results in those affected areas, with deaths being reported as well as widespread destruction.\ud \ud Research and information gathered from these events have been incorporated into the latest edition of AS/NZS 1170.2-2011 to now represent a more realistic determination of wind actions.\ud \ud The Standard applies to structures ranging from 'the less sensitive to wind action to those for which dynamic response must be taken into consideration'.\ud \ud This handbook was prepared by the AWES to provide background information into wind and its actions, but also into the derivation of the Standard and its contents.\ud \ud It covers items such as:\ud \ud • Nature of wind loading\ud \ud • Wind speeds and multipliers\ud \ud • Shape factors for structures\ud \ud • Dynamic response\ud \ud In particular, it equips users with a better understanding of wind and the Standard to provide them with improved interpretation and judgment in determining wind actions on structures.\ud \ud Equally important, it enables the user to extend the Standard limitations while still complying with regulations, albeit other information may be necessary