Seismic isolator base displacement at base level

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Context 1

... structure with a seismic isolation system can exhibit almost rigid superstructure behaviour in an earthquake motion as well as the flexibility needed to reduce floor accelerations with the isolation zone of large displacements. In this context, it has the rigidity required to reduce the relative floor displacements. During the first dynamic mode of the structures in which the base insulation systems are applied, the displacement is only at the isolation level. The top modes producing displacement are orthogonal to the first mode and hence the ground motion. Participation of these upper modes to the motion is very low ( Figure 2) [2]. The effective resonance period of a structure is usually between 0.1 and 1.0 second. This period also includes the dominant period of many violent earthquakes [3]. Since the elastic first vibration periods of the seismic base insulated structures are considerably larger than the fixed base construction, the elastic first vibration periods are enlarged (Figure 3), it is provided to move away from the resonance zone, at which earthquake is very dangerous for structures. Thus, the magnitude of ground acceleration is prevented by the structure [4]. A typical design ...

Context 2

... current system model has been solved with time history method without any changes in material characteristics and cross sections. Acceleration records of 1999 Marmara earthquake recorded at Duzce meteorology station are utilized (Figures 10 and 11). The time period is 0.005 s, the maximum acceleration value is 3.73 m/s 2 for East-West and 3.14 m/s 2 for North-South. According to the analysis results, in all three floors, shear-walls are found to be inadequate (Table IV). In vertical load bearings, 15 of the 42 existing columns are found to be inadequate (Table V). Columns 1st floor 2nd floor 3rd floor SZ02 S102 S202 SZ05 - - SZ07 S107 S207 SZ10 S110 S210 SZ11 - - SZ12 - - SZ14 S114 - SZ15 - - The analysis is renewed by placing the base isolation in the base-column junction of the present school building, which consists of shear wall-frame. DIS B type lead core rubber isolator manufactured by Dynamic Isolation Systems Company is used for the base isolation material. The characteristic of this isolator is shown in Table VI. The linear and nonlinear damping of the isolator and the yield strength assignments are performed and the results are shown in Figure 12 [11]. The natural vibration frequency of the isolated structure has now been determined. According to this, the 1st mode of the building is 1.7407 s in the Z direction (torsional direction) ( Figure 13) in the Y direction ( Figure 14). The third mode is 1.6458 s in the X direction. (Figure 15). The existing system with base isolation has also been solved in nonlinear time history method. As a result of the analysis made on the basis of the acceleration records in Figures 10 and 11, it is seen that all the sections are sufficient in contrast to the current situation and no capacity problem is encountered. The 1st period of the classical analysis is 0.2165 s in the Y direction . While the 1st period of the base isolated system is in the direction of Z (torsion direction) and equal to1.7407 s. ...