Sergey Kuznetsov

Influence of Stationary Vehicles on Bridge Aerodynamic and Aeroelastic Coefficients

AbstractThis study focuses on modifications in bridge aerodynamic and aeroelastic behaviors due to stationary (nonmoving) vehicles for various arrangements of vehicles on a bridge deck. Dimensionless aerodynamic force and moment coefficients, as well as flutter derivatives, are analyzed experimentally in a wind tunnel in the model of a bridge with a semibluff cross section. A comparison is provided for stationary vehicles placed in leeward, windward, and all traffic lanes, as well as for an empty bridge-deck section. Drag, lift static forces, and moment coefficients are determined for various wind incidence angles. Flutter derivatives are obtained using the free-vibration technique for both one- and two-degrees-of-freedom systems. Stationary vehicles on the bridge deck are generally observed to change aerodynamic coefficients of the bridge. This is particularly exhibited for the pitch moment. Galloping sensitivity of the bridge does not change considerably in the presence of vehicles, as all studied confi...

Influence of placement and height of high-rise buildings on wind pressure distribution and natural ventilation of low- and medium-rise buildings

ABSTRACT High-rise buildings influence wind characteristics in complex urban areas and can significantly change the natural ventilation in adjacent low- and medium-rise buildings. The results of previous studies show that the windward zones of high-rise buildings can create adverse effects on natural air ventilation because they reverse the flow regime, simultaneously almost double the wind suction of downwind air zones, and increase the heat loss of smaller structures due to the resulting pressure distribution on the facade. In this study, the pressure distribution of low- and medium-rise buildings is measured in wind tunnels and discussed. It focuses on the fundamental understanding of the effects of high-rise building height and distance from adjacent structures on wind flow characteristics and natural ventilation. The study uses a pair of building models tested in a set of parametric experiments, comprising pressure measurements and particle image velocimetry (PIV).

Climatic wind tunnel for wind engineering tasks

this paper introduces a new climatic wind tunnel laboratory, which is one of the laboratories of the institute of theoretical and applied mechanics (itam) of the academy of Science of the Czech republic. the tunnel is used for fundamental research in civil engineering, architecture, and heritage care and in other fields where wind effects appear along with other factors. the paper includes essential information about the interior layout of the tunnel, descriptions of the principal parts of the tunnel which were designed taking into account both the optimal flow characteristics together with the description of some facilities serving for the simulation of a strong wind, rain, freeze and heat radiation, and the modelling of the atmospheric boundary layer. a design for a rectangular contraction nozzle, based on a parabolic profile and extending the capacity of the wind tunnel is presented.

Wake Characteristics of Ice-Accreted Cylindrical Bars in a Cross-Flow at Subcritical Reynolds Numbers

AbstractIce accretion can considerably alter aerodynamic characteristics of bridge cables. The present study focuses on flow characteristics in the cable wake for three arrangements of ice accretio...

Wind-Tunnel Experiments on Vortex-Induced Vibration of Rough Bridge Cables

Surface roughness, ice accretion, and atmospheric turbulence are important issues because they can considerably alter the aerodynamic characteristics of bridge cables. The present study describes wind-tunnel experiments on vortex-induced vibrations of rough bridge cables characterized with various surface roughness and performed at various levels of atmospheric turbulence. Three different cable models were used: a smooth cylinder to represent dry cables, a helical strand cable, and a cable with modeled ice accretion. The studied parameters include the critical velocity and amplitude of vortex-induced vibration and parameter sensitivity to changes in flow turbulence and cable surface roughness. The results obtained indicate that cable roughness and turbulence of the flow have significant influences on the dynamic response of bridge cables. The experimental results indicate that the vortex-induced vibration was largest for the ice-accreted bridge cable.

Investigations of Strouhal numbers of iced cable models of cable-supported bridges with respect to angle of wind attack

Investigations of Strouhal numbers of iced cable models of cable-supported bridges with respect to angle of wind attack