scholarly journals MULTIPLE REGRESSION MODELING OF NATURAL RUBBER SEISMIC-ISOLATION SYSTEMS WITH SUPPLEMENTAL VISCOUS DAMPING FOR NEAR-FIELD GROUND MOTION

2013 ◽  
Vol 19 (5) ◽  
pp. 665-682 ◽  
Author(s):  
Mohammad H. Alhamaydeh ◽  
Samer A. Barakat ◽  
Farid H. Abed
Keyword(s):  
Natural Rubber ◽  
Multiple Regression ◽  
Ground Motion ◽  
Seismic Isolation ◽  
Near Field ◽  
Earthquake Ground Motion ◽  
Maximum Displacement ◽  
Fixed Base ◽  
Rubber Bearings ◽  
Seismic Isolation Systems

This work presents the development and implementation of the Multiple Regression Analysis (MRA) model to Seismic-Isolation (SI) systems consisting of Natural Rubber Bearings and Viscous Fluid Dampers subject to Near-Field (NF) earthquake ground motion. A model representing a realistic five-story base-isolated building is used. Several damper properties are used in creating an array of feasible combinations for the SI system. Two ensembles of seven NF earthquake records are utilized representing two seismic hazard levels. The key response parameters investigated are the Total Maximum Displacement, the Peak Damper Force and the Top Story Acceleration Ratio of the isolated structure compared to the fixed-base structure. Mathematical models for the key response parameters are established via MRA. The MRA models produced acceptable results with significantly less computation. This is demonstrated via a practical example of how the MRA models would be incorporated in the design process, especially at the preliminary stages.

DESIGN FORCE TRANSMITTED BY ISOLATION SYSTEM COMPOSED OF LEAD-RUBBER BEARINGS AND VISCOUS DAMPERS

2010 ◽  
Vol 10 (02) ◽  
pp. 287-298 ◽  
Author(s):  
J. S. HWANG ◽  
C. F. HUNG ◽  
Y. N. HUANG ◽  
S. J. WANG
Keyword(s):  
Phase Angle ◽  
Seismic Isolation ◽  
Soft Soil ◽  
Near Field ◽  
Viscous Dampers ◽  
Maximum Displacement ◽  
Isolation System ◽  
Lead Rubber Bearings ◽  
Response History Analysis ◽  
Rubber Bearings

In seismic isolation design of structures located at soft soil sites or near field areas, viscous dampers (VD) are often included as part of the isolation system to minimize its maximum displacement. Due to the 90° phase angle existing between the force and displacement of the VD, the maximum force transmitted by the isolation system cannot be calculated by simply combining the forces of the isolation bearings, such as lead-rubber bearings (LRB) or high damping rubber bearings (HDRB), and VD in association with the design displacement. Conforming to the code-specified equivalent lateral response procedure for isolation design, this paper presents a formula for determining the seismic design force of the combined LRB and VD isolation system, taking into account the phase angle between the combined force of the LRB and VD and the displacement of the isolation system. The numerical results have shown that the maximum responses of the isolation system predicted by the proposed formula are conservative and comparable with those from the inelastic dynamic response history analysis.

scholarly journals Large-scale experimental investigation of a low-cost PVC ‘sand-wich’ (PVC-s) seismic isolation for developing countries

2020 ◽  
Vol 36 (4) ◽  
pp. 1886-1911 ◽  
Author(s):  
Anastasios Tsiavos ◽  
Anastasios Sextos ◽  
Andreas Stavridis ◽  
Matt Dietz ◽  
Luiza Dihoru ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Developing Countries ◽  
Ground Motion ◽  
Seismic Isolation ◽  
Large Scale ◽  
Low Cost ◽  
Seismic Energy ◽  
Earthquake Ground Motion ◽  
Isolation System ◽  
Seismically Isolated

This study presents a large-scale experimental investigation on the seismic performance of an innovative, low-cost seismic isolation system for developing countries. It is based on the beneficial effect of the encapsulation of sand grains between two PVC surfaces on the initiation of sliding and the dissipation of seismic energy between the surfaces. A three-times scaled-down, idealized, seismically isolated model of a prototype single-story structure located in Nepal is subjected to an ensemble of recorded earthquake ground motion excitations. The experimentally derived response of the seismically isolated structure is compared with the response of the corresponding fixed-base structure. This system is part of a wider hybrid design approach where the structure is designed to resist the seismic forces at the design acceleration level. The seismic isolation system sets an upper bound to the response of the structure for ground motion excitations exceeding the design level.

Response Analysis of a Seismic Isolated Structure Considering the Nonlinearity of the Rubber Bearings

2013 ◽  
Author(s):  
Alexandre Borsoi ◽  
Satoshi Fujita ◽  
Keisuke Minagawa
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Industrial Structure ◽  
Response Analysis ◽  
Vertical Load ◽  
Restoring Force ◽  
Seismic Safety ◽  
Rubber Bearings ◽  
Seismic Isolation Systems

In Japan, the application of seismic isolation systems using rubber bearings to industrial structure and new generation Nuclear Power Plants have been considered in order to enhance seismic safety. However, the isolation performance will decline in case of huge earthquakes, because of the nonlinearity of both horizontal and vertical restoring characteristics of the rubber bearings. The horizontal restoring force has a hardening characteristic and the vertical restoring force has a softening characteristic. In addition, the horizontal nonlinearity depends on vertical load, so the interaction between the horizontal and vertical response is important. Consequently, in this paper, the analysis of the nonlinearity of the rubber bearings and the coupling between those two directions will be carried out. Then, after comparing these two approaches, the utility of considering this dependency will be estimated. To do so, a simulation program, based on the Runge-Kutta-Gill’s method has been developed in order to evaluate the seismic response of the isolated structure composed of rubber bearings and oil dampers. The nonlinearity of the rubber bearings is considered, and the coupling of the vertical load and the horizontal hardening has been implemented.

scholarly journals Seismic Performance of Midstory Isolated Structures under Near-Field Pulse-Like Ground Motion and Limiting Deformation of Isolation Layers

2015 ◽  
Vol 2015 ◽  
pp. 1-17 ◽  
Author(s):  
Guiyun Yan ◽  
Fuquan Chen
Keyword(s):  
Ground Motion ◽  
Nonlinear Response ◽  
Near Field ◽  
Field Pulse ◽  
Isolation Layer ◽  
Protective System ◽  
Lead Rubber Bearings ◽  
Isolated Structures ◽  
Rubber Bearings ◽  
The Impact

Excessive deformation of the isolation layer in midstory isolated structures may occur under strong near-field pulse-like ground motion, which would result in the overturning collapse of the superstructure. The objective of the present research is to limit excessive deformation of the isolation layer and to reduce nonlinear response of midstory isolated structures. To this end, a protective system is presented to limit deformation of the isolation layer by soft pounding. Based on the Kelvin pounding model, a mechanical model is put forward for this protective system. In addition, a new method has been proposed that synthesizes artificial near-field pulse-like ground motion by combining the real near-field nonpulse ground motion with simple equivalent pulses. Also, the impact of artificial near-field pulse-like ground motion on the nonlinear response of midstory isolated structures and the deformation of the isolation layer has been investigated. The effectiveness of the midstory isolation with the protective system has been validated. The results show that the maximum deformation of the isolation layer significantly exceeds the allowable deformation of lead-rubber bearings when subjected to near-field pulse-like ground motion, and it causes the lead-rubber bearings destruction. The proposed protective system is effective in restricting the excessive deformation of the isolation layer and reducing nonlinear responses of the isolated structure, preventing collapse of the superstructure.

scholarly journals Evaluation of Steel Frame Structures with the Response of Seismic Isolators

2020 ◽  
Vol 30 (3) ◽  
pp. 24-47
Author(s):  
Mohammad Beykzade ◽  
Alireza Baghchesaraei ◽  
Omid Reza Baghchesaraei
Keyword(s):  
Structural Damage ◽  
Seismic Isolation ◽  
Frame Structures ◽  
Natural Period ◽  
Input Force ◽  
Fixed Base ◽  
Steel Frame Structures ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Over Time

Abstract As science keeps evolving over time, new solutions are being put forward for reducing structural damage. One such solution is the use of seismic isolation systems. Seismic isolation systems reduce the response of structures to the force of earthquakes by reducing the input (force) acceleration when the natural period of the structure increases. Therefore, the use of seismic isolation systems is recommended in the analysis of diverse structures. This study was carried out on seismically isolated buildings with 8, 10, and 12 regular steel floors, modeled by a non-linear isolator in two-, or three-second periods. The differences in data and the responses of the buildings were compared with fixed-base buildings with 8, 10, and 12 floors.

scholarly journals Retrofit of seismically isolated structures for near-field ground motion using additional viscous damping

2005 ◽  
Vol 38 (2) ◽  
pp. 106-118 ◽  
Author(s):  
Lyle P. Carden ◽  
Barry J. Davidson ◽  
Tam J. Larkin ◽  
Ian G. Buckle
Keyword(s):  
Ground Motion ◽  
Near Field ◽  
Flexible Structures ◽  
Earthquake Ground Motion ◽  
Viscous Damping ◽  
Original Design ◽  
Large Magnitude ◽  
Isolated Structures ◽  
Seismically Isolated ◽  
The Impact

Recent earthquakes have shown that a large magnitude, long period pulse is often prevalent in ground motion records at sites within a few kilometres of the active fault during an earthquake. Near-field earthquake ground motion containing forward directivity effects can result in a larger response in flexible structures, such as seismically isolated structures, compared to that predicted for conventional ground shaking. Hence, a study was performed on a number of generic seismically isolated structures designed to the 1997 Uniform Building Code, as well as a case study on the William Clayton building in Wellington, to determine the impact of near-field ground motion. In optimising the performance of the buildings for both near-field and original "design level" earthquakes, it is concluded that linear viscous dampers added to the existing isolation systems are effective in controlling the response during large magnitude near-field earthquakes with minimal impact on the design response. Additional viscous damping is more effective than hysteretic damping in limiting isolator displacements while also preventing an increase in base shear and floor accelerations for far-field "design level" earthquakes.

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