Wind Dynamic Response Research Articles

Studies on the influence factors of wind dynamic responses on hyperbolic cooling tower shells

Wind induced dynamic responses on hyperbolic cooling tower (HCT) shells are complicated functions of structure and wind properties, such as the fundamental frequency fmin, damping ratio zeta wind velocity V, correlationship in meridian direction and so on, but comprehensions on the sensitivities of the dynamic responses to these four factors are still limited and disagree from each other. Following the dynamic calculation in time domain, features of dynamic effects were elaborated, focusing on the background and resonant components SigmaB and SigmaR, and their contributions to the total rms value SigmaT. The SigmaR is always less than SigmaB when only the maximum SigmaT along latitude is concerned and the contribution of SigmaR to SigmaT varies with responses and locations, but the SigmaR couldn\'t be neglected for structural design. Then, parameters of the above four factors were artificially adjusted respectively and their influences on the gust responses were illustrated. The relationships of SigmaR and the former three factors were expressed by fitted equations which shows certain differences from the existing equations. Moreover, a new strategy for wind tunnel tests aiming at surface pressures and the following dynamic calculations, which demands less experiment equipment, was proposed according to the influence from meridian correlationship.

Wind-induced vibrations of structures using design spectra

This paper discusses the estimation of wind dynamic response of two types of structures by following classical and novel approaches. A new method for structural analysis based on wind design spectra is introduced and tested against simulated and experimental data. Design spectra are derived from the dynamic response of a group of oscillators subject to wind, using similar techniques than those used to derive design spectra for seismic engineering applications. The method is used on three chimneys of different height as well as on a regular building which has been experimentally tested in the past. The chimneys and building are also submitted to simulated wind fields to provide additional sets of results. It is observed that the spectral approach is consistent with experimental and simulated results and therefore is concluded that design spectra can cover broad range of practical applications.

Wind loads on a high slender tower: Numerical and experimental comparison

This paper compares the wind loads measured experimentally in wind tunnel tests and those predicted by Eurocode on a high slender tower with a porous external surface forming an intricate three-dimensional spiral. In the experimental tests a rigid and an aeroelastic model of the tower were tested in low and high turbulent flow conditions. The aim of the wind tunnel tests was to evaluate the wind actions at the base of the structure and, comparing the results from the two models, to verify the presence of possible aerodynamic effects, such as force fields due to fluid–structure interaction. The along wind dynamic response of the tower calculated experimentally was then compared with the results obtained numerically using Eurocode, under the hypothesis of negligible aeroelastic effects. It was found that Eurocode may underestimate the effect of certain exposures. Aerodynamic damping was also evaluated.

Wind-Induced Responses Study and Wind-Resistant Design of Super-Long-Span Cable-Membrane Roof Structure of Shenzhen Baoan Stadium

In this paper, the system and the design philosophy of wheel-spoke cable-membrane structure of Baoan Stadium is introduced firstly. And then the study of wind tunnel test on 1:250 scale model is mainly presented, together with the numerical calculation of the wind dynamic response. Finally, the wind-resistant design of the roof structure based on the results of wind tunnel test and the foreign design codes is generally introduced.

Control of the earthquake and wind dynamic response of steel‐framed buildings by using additional braces and/or viscoelastic dampers

AbstractThe insertion of steel braces equipped with viscoelastic dampers (VEDs) (‘dissipative braces’) is a very effective technique to improve the seismic or wind behaviour of framed buildings. The main purpose of this work is to compare the earthquake and wind dynamic response of steel‐framed buildings with VEDs and achieve optimal properties of dampers and supporting braces. To this end, a numerical investigation is carried out with reference to the steel K‐braced framed structure of a 15‐storey office building, which is designed according to the provisions of Eurocodes 1 and 3, and to four structures derived from the first one by the insertion of additional diagonal braces and/or VEDs. With regard to the VEDs, the following cases are examined: absence of dampers; insertion of dampers supported by the existing K‐braces in each of the structures with or without additional diagonal braces; insertion of dampers supported by additional diagonal braces. Dynamic analyses are carried out in the time domain using a step‐by‐step initial stress‐like iterative procedure. For this purpose, the frame members and the VEDs are idealized, respectively, by a bilinear model, which allows the simulation of the nonlinear behaviour under seismic loads, and a six‐element generalized model, which can be considered as an in‐parallel‐combination of two Maxwell models and one Kelvin model. Artificially generated accelerograms, whose response spectra match those adopted by Eurocode 8 for a medium subsoil class and for different levels of peak ground acceleration, are considered to simulate seismic loads. Along‐wind loads are considered assuming, at each storey, time histories of the wind velocity for a return period Tr=5 years, according to an equivalent spectrum technique. Copyright © 2010 John Wiley & Sons, Ltd.

A More Precise Computation of Along Wind Dynamic Response Analysis for Tall Buildings Built in Urban Areas

Modern tall buildings are generally built in urban areas, where value of the terrain roughness length is much greater than that of the general terrain areas, therefore wind-induced vibrations become more pronounced. The present formulas of numerical analysis of wind-induced response become less accurate. A more accurate expression of along-wind load spectrum matrix is proposed. On the basis of the expression, structural analysis formula of along-wind displacement and acceleration response are developed and programmed. The rationality of these formulas are illustrated in examples.

Comparative study of the earthquake and wind dynamic responses of base-isolated buildings

Abstract The base isolation is a very effective technique for reducing the seismic forces through a decoupling of the structure motion from that of the soil. With regard to the earthquake, the insertion of a very flexible base-isolation system is generally favourable, particularly for reducing the ductility demand (i.e., for controlling the ultimate state). On the other hand, under wind a considerable increase of deformability of the isolated structure – in comparison with that of the fixed-base structure – can lead to displacements at the top of the isolators and accelerations at the floor levels so large that serviceability limit states (particularly, the discomfort threshold) have to be carefully checked. The main purpose of this paper is to study the dynamic response of base-isolated structures subjected to strong earthquakes or wind loads in order to pursue an optimal design of the base-isolation system. For this purpose, a numerical investigation is carried out with reference to three- and five-storey reinforced concrete (r.c.) framed structures, isolated by high-damping-laminated-rubber bearings (HDLRB). The results, obtained by a step-by-step procedure, show a different behaviour of the test structures subjected to earthquake or wind when assuming different levels of deformability of the isolators within a wide range of variation.