Application and superiority analysis of standard parts in anti-vibration system
These existing isolation technologies still have some defects, or the system is complicated, the implementation cost is high; or the structural components are vulnerable and the service life is limited. The essence of the isolation is to isolate the structure from the source. The effectiveness of the isolation system is mainly reflected in the extent to which the system is isolated from the source. The more complete the isolation, the more effective the isolation system. Accordingly, we have conceived a vertical spring-steel ball isolation system consisting of steel balls, bolts and vertical springs. The steel ball bears the vertical pressure of the structure above the pier. When the earthquake occurs, it only gives the structural foundation horizontal rolling friction resistance, and its size is 1/20o of the total weight of the superstructure. The bolt keeps the structure stable under normal horizontal load. When the seismic force exceeds the normal load, it is cut. The vertical spring provides a horizontal restoring force. The superstructure can be automatically reset instantaneously and eliminate residual displacement after the earthquake. The seismic acceleration response ratio of the traditional anti-vibration structure is 2 to 4, which is 3 to 6 degrees compared with the reduction of the seismic intensity. During the design, the isolation system is considered to be 2 to 3 degrees relative to the reduced seismic intensity, which not only allows the upper structure to have a large safety reserve, but also reduces the section and reinforcement of the component, and reduces the cost. Technical and economic benefits.
Like the steel ball isolation system, the friction coefficient is also the main controlling factor for the seismic relative displacement response of the vertical spring-steel ball isolation system, that is, the friction coefficient increases and the relative displacement response of the structure becomes smaller. In short, as long as the stiffness of the vertical spring is properly selected, the vertical spring-steel ball isolation system will exhibit the advantages of both the elastic (viscous) type isolation system and the pure friction isolation system, and eliminate some of the two. Insufficient aspects. Since the horizontal stiffness of the vertical spring is small, the horizontal spring force is small. The maximum friction of the steel ball is the product of the weight of the superstructure and the coefficient of friction. The friction coefficient is small and the friction is inevitably small. This is the fundamental principle of various isolation of the isolator. The fundamental function of various isolation devices is to isolate the impact force transmitted by the seismic action to the superstructure, not to absorb seismic energy. It is a well-known fact that moving objects have kinetic energy. When a moving object hits a stationary object, the impact force generated by its kinetic energy is related to the characteristics of the object being struck. If the object being hit is very soft, causing a large deformation, the impact force is small, and the object is not hit, and the kinetic energy of the moving object is converted into the work of the impact force on the deformation of the object and is absorbed. The effect of ground motion on the structure has no kinetic energy conversion because the seismic waves continue to propagate forward. When the structure is consolidated on the ground, the structure is subjected to the same acceleration as the seismic wave. If the earthquake acceleration is large, the structure will generate a large inertia force and be destroyed. If it is a minor earthquake, the structure will not be damaged, and it will not be damaged. After the foundation is installed, the structural foundation will be horizontally displaced relative to the foundation during the earthquake. The horizontal shear deformation of the isolator can be known. At this time, the effect of the ground motion on the superstructure is the elastic or frictional force of the isolator. The acceleration of the superstructure generated by this force is not equal to the seismic wave acceleration. When the design of the isolator is appropriate, the acceleration is much smaller than the seismic acceleration, thus achieving the isolation. the goal of.
The analysis of the isolation effect of the vertical spring-steel ball isolation system compares the influence of friction coefficient and damping ratio on the isolation effect. It can be found that the elastic (viscosity)-friction isolation system, such as the vertical spring-steel ball isolation system And the PTFE plate isolation system (R-FBI system), the main mechanism for the isolation is friction, that is, the friction between the isolation layer and the superstructure foundation is the key factor to determine the isolation effect. Although the isolation system consumes energy by friction during seismic action, the effect transmitted to the superstructure is clearly the friction of the steel ball and the horizontal spring force of the vertical spring, rather than the energy transmitted by the seismic wave to the superstructure. According to Newton's second law: the object is subjected to an external force, generating a new acceleration a, the larger the a, the greater the inertial force of the object, and vice versa. If the friction and spring force are large, the upper structure l) vertical spring-steel ball isolation system has obvious isolation effect. The system mainly isolates seismic forces instead of absorbing energy. 2) The damping ratio of the isolation layer increases, and the seismic displacement of the system decreases, but the damping ratio of the isolation layer has less influence on the seismic response of the structure. 3) When the rolling friction coefficient of the steel ball is >0 Han X)5, the seismic response of the structure is intensified with the increase of the friction coefficient. 4) The horizontal stiffness of the spring can effectively eliminate the residual displacement after the earthquake and play a major role in adjusting the natural vibration period of the isolation system.
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