1,721,000 research outputs found
A NUMERICAL MODEL FOR SIMULATING UNILATERAL RESPONSE IN CROSS-TIES DURING FREE VIBRATION OF “CABLE-CROSS-TIE SYSTEMS
No full textGENERALIZED STIFFNESS MODEL FOR THE SIMULATION OF NONLINEAR FREE-VIBRATION IN “CABLE-CROSS-TIE SYSTEMS
No full textOSSERVAZIONI SUL COMPORTAMENTO DINAMICO NON-LINEARE NEI SISTEMI STRALLI-CONNETTORI PER IL CONTROLLO DELLE VIBRAZIONI INDOTTE DAL VENTO
No full textA gyroscopic stabilizer to improve flutter performance of long-span cable-supported bridges
No full textLong-span cable-supported bridges are gaining considerable importance in the world. It is generally recognized that long-span cable-supported bridges can be very sensitive to wind effects due to their aerodynamic properties and deck flexibility. Flutter is usually a major concern because it can lead to structural deck failure. This communication introduces a prototype of gyroscopic device as an active stabilizer for improving flutter performance. A mathematical model of the gyroscopic device, installed at the bridge deck level, was studied and implemented to assess its effectiveness in increasing the critical wind speed. A preliminary study was conducted to evaluate the stabilizer's performance on a benchmark long-span cable-supported bridge as a function of its gyricity. The results demonstrate that the gyroscopic stabilizer is very successful and bridge flutter threshold increases with the gyricity of the gyroscopic device, within a practical operational range
Parametrical DesignTrends for a Hyperbolic Paraboloid shaped over a square plan: Vertical Displacements and Natural Periods
No full textTensile structures are one of the most convenient solutions for covering large spans. For both temporary and permanent uses, they are optimal as sport arenas, meeting rooms or concert halls. However, codes and literature neglect these structures thus making it difficult to carry out preliminary designs for this structural typology in order to estimate the cost-benefit ratio compared to others. On the contrary, parametric equations used to preliminarily estimate the static and dynamic behavior of these structures are useful to designers. In order to give parametric information about some examples of these structures, this paper investigates the initial natural frequency and vertical displacements under dead and permeant loads of cable nets, with a hyperbolic paraboloid shape and square plan, depending on geometry. In total, two curvatures of a hyperbolic paraboloid surface and five different plan sizes are calculated with eight different cable tractions in order to give design trends. The trends are illustrated with an error bar resulting from the variation between different tractions considered for each geometry. The results are useful to preliminarily estimate the cost and the range of interference between wind and structure
Digital simulation of wind field velocity for evaluating proper stiffness indicators of window mullions
No full textMullions are important structural windows elements that provide their resistance to wind forces. These elements are of fundamental importance for the energy balance of the building since their structural behavior deeply affects its energy losses. A proper structural design of the windows mullions is therefore important for evaluating a suitable stiffness indicator of the mullions to avoid energy losses. In the present paper, a parametric study aiming to investigate the wind-induced displacements of the window mullions and their compatibility with their thermal barrier has been conducted. The proposed study aims to evaluate a proper moment of inertia of the aluminum profiles forming the mullions as a function of the windows exposition for different wind forces depending on the elevation of the building in which the window has been installed
Improving Long-Span Bridge Flutter Reliability Through Gyroscopic Stabilizer, Considering Random Aeroelastic Loads
No full textLong span suspension bridges are challenging structures, generally sensitive to wind effects and to wind-induced instabilities. Torsional rotation of the bridge deck plays an important role for the dynamic stability of the structure. This study uses a gyroscopic device as a stabilizer of the long span bridge. The proposed apparatus has been modeled as a lumped 3DOF system installed inside a specific section of the bridge deck. To assess effectiveness in increasing the critical flutter wind speed and performance, a numerical study is conducted on a benchmark long-span cable-supported bridge as a function of apparatus’ gyricity. Deck aeroelastic loads are randomly perturbed to simulate modeling simplifications and measurement errors. Monte Carlo simulations are used to predict flutter probability and efficiency of the stabilizer, within a practical operational range, in the presence of random aeroelastic loads
Parametrical design trends for a hyperbolic paraboloid shaped over a square plan: Vertical displacements and natural periods
No full textTensile structures are one of the most convenient solutions for covering large spans. For both temporary and permanent uses, they are optimal as sport arenas, meeting rooms or concert halls. However, codes and literature neglect these structures thus making it difficult to carry out preliminary designs for this structural typology in order to estimate the cost-benefit ratio compared to others. On the contrary, parametric equations used to preliminarily estimate the static and dynamic behavior of these structures are useful to designers. In order to give parametric information about some examples of these structures, this paper investigates the initial natural frequency and vertical displacements under dead and permeant loads of cable nets, with a hyperbolic paraboloid shape and square plan, depending on geometry. In total, two curvatures of a hyperbolic paraboloid surface and five different plan sizes are calculated with eight different cable tractions in order to give design trends. The trends are illustrated with an error bar resulting from the variation between different tractions considered for each geometry. The results are useful to preliminarily estimate the cost and the range of interference between wind and structure
DYNAMIC ANALYSIS FOR STRUCTURAL UPGRADE OF FOOTBRIDGE LOCATED IN CANNA’S RIVER IN CARBONIA (ITALY)
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