Displacement Of Isolation Layer Research Articles

Dynamic model and earthquake response of a hybrid isolated system with tuned inerter dampers for nuclear power plants

Considering the benefits of tuned inerter damper (TID), a hybrid control system (TIDISO system) for third-generation NPPs consisting of an un-isolated outer containment structure, an isolated inner containment structure and a connecting TID system was proposed. First, governing equations of motion for the 3-degree-of-freedom (3DOF) model were derived and the seismic response variances of TIDISO system under white noise excitation were obtained. Next, an optimization study on inertance, frequency and damping parameters was conducted, and then simplified expressions were provided as a function of the various structural parameters for the optimal TID parameters. Through simulation comparisons, the accuracy of the expressions was further verified. Finally, a case study was conducted to demonstrate the proposed rapid-determining formula for optimal TID parameters and to estimate the effectiveness of the proposed TIDISO system under seismic waves. The results illustrate the proposed system is effective to suppress acceleration and story draft responses, especially for isolation displacement. Under artificial wave 1, the displacement of isolation layer has declined from 475 mm to 327 mm, nearly 32.7%.

Experimental Validation of Numerical Model for Bi‐Tilt‐Isolator

Bi‐Tilt Isolator (BTI) is composed of bi‐tilt beveled substrate and slider. The advantages of BTI are that the maximum upload seismic force of structure can be easily controlled and displacement of isolation layer will be reduced. Sliding force, friction force, and impulse force are caused in the slanting process of BTI, nonlinear behavior. A nonlinear mathematical model is derived based on the sliding upwards, sliding downwards, and transition stages. Then, BTI element of nonlinear analysis program, GENDYN, is developed by the fourth‐order Runge‐Kutta method, the discretized ordinary differential equation for three movement stages of BTI. Then, test set‐up of superstructure installed with BTI is tested and recorded the real displacement and acceleration responses under conditions of full lubrication, mild lubrication, and without lubrication between interface of bi‐tilt beveled substrate and slider with three various initial displacements. The comparison of simulation results and test results shows the following: (1) root mean square error is below 1.35% for WD40 sprayed, 0.47% for WD40 whipped, and 0.54% for without lubrication, respectively; (2) the maximum root mean square error for simulating with cubic polynomial function of friction is much less than those of constant friction except conditions of full lubrication, which are not affected by kinetic friction force; (3) application of cubic polynomial function for simulating friction of BTI with three different lubricated conditions can perform very fine simulation results, compared with the test results. This proposed mathematical model and BTI element of GENDYN program, using cubic polynomial function of friction, perform fine simulation capability to assess nonlinear isolation effect of structure installed with BTI.

Research on Numerical Simulation of Smart Base Isolation System with MR Damper (I)

Rubber bearing base-isolation is well-developed vibration reduction technique and is applied in practical engineering broadly. The nature period of the base-isolation structure applied with rubber bearing is extended. Meanwhile the response of the superstructure is also reduced. But it is noticed that the displacement of isolation layer is too large. So it is required to find a suitable damper to reduce the displacement of isolation layer. Magnetorheological damper has good smart performances- broad controlled band, fast response and demand a little energy. In this paper smart base isolation system, which is combined with rubber bearing and MR damper is applied to structural vibration control, and have numerical simulation e of structure employing RB isolation and smart isolation in different kind and magnitude of earthquake waves. The result indicates the control system is effective.

Research on the Base-Isolation Efficiency of Large-Scale Terminal

Terminal No. A of Kunming International Airport (TA) is a complex steel-concrete hybrid structure. The airport is located in Kunming, China; the seismic fortification intensity is 8 degree. After multi-analysis, base-isolation technique is applied to the structure, and the terminal will be the biggest base-isolated monomer building in the world after its accomplishment. By using ANSYS, the structural FEM model, which is mainly composed of linear beams elements, linear shells elements and nonlinear isolator elements, was established. Demonstration of isolation schemes and influence of isolator’s layout to the isolation efficiency were firstly introduced. And the selection processes of earthquake waves were introduced. Finally, the elastic time history analysis was carried out to study the seismic performance and isolation efficiency of the structure under the frequently and rarely occurred earthquakes. The results showed that not only the expected shock-absorption goal of ‘reduce 1 degree’under frequently occurred earthquakes is achieved, but also the maximal shear displacement of isolation layer under rarely occurred earthquakes can meet the Chinese code requirements. It is concluded that the design of isolation layer is appropriate; the isolation efficiency of the structure after applying base-isolation technique can meet the challenge.