Structure Galloping Theory Analysis And Wind Vibration Control

Wind disaster is regarded as one of the most terrible natural disasters. At present, civil engineering structures have the development tendency towards large-scale, high and flexible direction, The impact of wind on the structure of high-rise building is becoming more and more notable. As a new wind resistance technique, structure vibration control, whose concept is simple and whose effect is observable, adapt to the different wind resistance request of civil engineering structures. This paper deals with some important problems such as galloping theory and wind vibration control, which mainly include:(1)The solution to differential equation of nonlinear movement initiated by cross wind galloping has been founded by using the three-series method firstly, and definite expression for harmonic behavior and critical wind speed is obtained. Some of the vital factors on possible occurrence of galloping were stated theoretically as follows: The slope of lifting line is of a larger negative result, I .e, which will likely occur only as non-streamlined cross-section form into the structure of airflow being separated and unlined. Sufficient conditions to form instability are known as structure heavy in mass, little in stiffness, little in damper, large in height (length) and large in ratio of length to narrowness. Equations derivated in this paper expatiated that nonlinear quadratic term for speed does not affect the value of critical wind speed, however, it makes galloping harmonic behavior enlarge, and causes frequency to be decrease. Therefore, the critical wind speed can be only be decided against one degree term, As for galloping behavior in a few of initial minutes, it almost depends on one degree term for speed. The numerical analysis of example indicates that this method is of much effectiveness and can be conveniently applied to engineering practice.(2)The coupled bending-torsional galloping oscillation caused by the beam wind in the tall building 3-dimentional structure was researched, its mathematical equation was derived by the infinitesimal element method and its decoupling and analysis were performed. The aerodynamic forces causing the structure oscillation were analyzed for the different angles induced between the airflow and the build structure. The stability conditions against the bending-torsional coupled galloping oscillation in the tall building...