Layer Interval Seismic Frame Structure Seismic Response Of Power Analysis

The mid-story isolation structure is a new type of seismic isolation structure, developed from the engineering practices of base-isolation technology.It solves limitations of the isolation layer position on base isolation technology, and expands the application scope of seismic isolation technology. But for the different positions of isolation layer, the damping effect of the structures also differ very obviously. This paper aims to figure out the damping effect and seismic response of the mid-story isolation structures, the main researchs are as follows:1. On base of the comparison and analysis of mechanical properties of kinds of isolation devices, this article has selected the appropriate restoring force model, and established the dynamic equation of mid-story isolation structures.2. With the finite element software SAP2000, the article simulated a reinforced concrete frame structure building, established six seismic isolation structure models with isolation layer in different floors.Based on the modal analysis, the results show that when the isolation layer in lower position,the isolated structure achieves the damping effect by extending the basic period. And when the isolation layer is located in a lower floor, the period becomes longer and the damping effect is better.And, when the isolation layer has a medium position, the higher mode's effect will increase.3. Using dynamic time-history analysis of all isolated structures, get the seismic responses of structures under mild and severe earthquake, including the floor shear force, displacement and acceleration. Comparing the seismic responses with the non-isolated structure, which shows that seismic isolation structures have good damping effect under both mild and severe earthquake, and the seismic responses develop as the same rule generally:with the upward of isolation layer's position, the damping ratios of each floor (except the isolation layer) always decrease, which indicates that the lower the location of isolation layer is, the better the damping effect is. But seismic response of the adjacent floors of isolation layer will mutate.4. Changing the horizontal stiffness and damping of the isolation layer, analysis on the influence of damping effect over isolated structures is addressed.Analysis shows that, for the upper floors of isolation layer, the smaller the horizontal stiffness is, structures get the better damping effect; but for the lower floors of isolation layer, there is a certain stiffness on which the seismic responses could be minimum, which qualifiess the whole structure to achieve a satisfactory damping effect. Analysis shows that damping is a positive factor for seismic-isolation structures, and the.greater the isolation layer damping is, the better the damping effect of the structures will achieve.