Reduction of structural response to near fault earthquakes by seismic isolation columns and variable friction dampers

2010 ◽  
Vol 9 (1) ◽  
pp. 113-122 ◽  
Author(s):  
Y. Ribakov
Keyword(s):  
Seismic Isolation ◽  
Structural Response ◽  
Friction Dampers ◽  
Near Fault ◽  
Variable Friction ◽  
Near Fault Earthquakes

Base Isolation Systems Employing Variable Friction Dampers Based on a STFT Controller

2011 ◽  
Vol 90-93 ◽  
pp. 1566-1575
Author(s):  
Zi Shu Dai
Keyword(s):  
Base Isolation ◽  
Isolation System ◽  
Friction Dampers ◽  
Near Fault ◽  
Active Isolation ◽  
Variable Friction ◽  
Isolation Systems ◽  
Near Fault Earthquakes ◽  
Rubber Bearings ◽  
Short Time

Conventional isolation systems may induce an excessive response in near-fault earthquakes. A new short time Fourier transformation (STFT) control algorithm for variable friction dampers (VFD) is developed to improve the performance of base isolation buildings in near-fault earthquakes. The STFT controller varies the clamping force in the VFD damper to achieve the response reduction. In addition, the STFT algorithm is implemented analytically on a multi degree of freedom system (MDOF) with laminated rubber bearings and variable friction dampers in Simulink environment. Three types of earthquakes representing a wide variety of ground motions are considered as the ground excitations in the simulation. The numerical show that, compared with conventional isolation systems, the semi-active isolation system controlled by the STFT algorithm can reduce the excessive response in near-fault earthquakes effectively.

scholarly journals Improving the Seismic Behavior of Symmetrical Steel Structures Under Near-Field Earthquake Using a Base Isolation Method Lead Rubber Bearing Isolator

2016 ◽  
Vol 10 (7) ◽  
pp. 10
Author(s):  
Musa Mazji Till Abadi ◽  
Behnam Adhami
Keyword(s):  
Seismic Isolation ◽  
Retaining Wall ◽  
Vertical Component ◽  
Steel Structures ◽  
Vertical Movements ◽  
Near Fault ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Fixed Base ◽  
Near Fault Earthquakes

<p>In this study, the function and application of seismic isolation system through lead rubber bearing isolator (LRB) in near-fault earthquakes are compared with fixed-base structures. As a result of their high frequency content, near-fault earthquakes impose huge energy on structures and cause severe damages. One of the appropriate solutions for this issue is the use of LRB which decreases the amount of imposed energy on structures. To improve the function of isolated structures under the near-fault earthquakes, isolators are designed in a way to tolerate the vertical component of earthquakes. To this purpose, we limit the displacements due to the horizontal movements of isolator through Gap spring which acts as a retaining wall and prevent shocks to other buildings. Moreover, this approach decreases the vertical movements of isolators and indirectly improves their behavior. In the current study, three buildings with four, eight, and 12 floors (with and without gap spring) were included. Isolators were manually designed in accordance with AASHTO-LRB regulations and the behaviors of both isolators and buildings are considered non-linear. Then we analyzed and compared the amount of energy, displacement, and acceleration of structure at the center of roof. The results indicated a significant decrease in the results of base shear, the acceleration of roof center, floors drift and energy imposed on the structure in the isolated system in comparison with the fixed-base structure.</p>

scholarly journals The Effect of Ground Motion Selection Methods for Seismic Design of Tall Buildings: A Case Study of Mandalay City

2020 ◽  
Vol 17 (12) ◽  
pp. 1348-1355
Author(s):  
Yan Naung KO ◽  
Teraphan ORNTHAMMARATH
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Active Faults ◽  
Structural Response ◽  
Tall Buildings ◽  
Lateral Force ◽  
Far Field ◽  
Ground Motion Selection ◽  
Near Fault ◽  
Near Fault Earthquakes

The near-fault earthquakes ground motion usually observed a few kilometers away from the active faults generally contains high energetic velocity pulses as a consequence of directivity effects. Mandalay city is located 8 km away from the Sagaing fault, and the comparative study is conducted to evaluate the structural response of 3 different types of Reinforced Concrete buildings - 4-story, 10-story, and 16-story buildings, respectively. These buildings are subjected to bi-directional ground motions selected from both far-field and pulse-like near-fault earthquakes. The far-field earthquakes produce less seismic demand on the buildings when compared to the near-fault earthquakes, where the ratio of the fundamental period of the building to the pulse period is significant. Comparing 2 ground motion selection and scaling methods of Tall Building Initiative guidelines - TBI (2010) and TBI (2017), the latter approach provides a more meaningful definition of intensity measure and allows reducing some conservatism. The structural response obtained from the design Equivalent Lateral Force (ELF) and Response Spectrum Analysis (RSA) is compared with the code-based linear Response History Analysis (RHA) results.

scholarly journals Performance Evaluation of bi-directional Roller Bearings for Seismic Isolation of Buildings Under Near-fault Earthquakes

2021 ◽  
Author(s):  
Nelson Ortiz-Cano ◽  
Ricardo González-Olaya ◽  
Carlos Gaviria-Mendoza ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Friction Force ◽  
Seismic Isolation ◽  
Sliding Friction ◽  
Roller Bearing ◽  
Experimental Tests ◽  
Element Model ◽  
Building Model ◽  
Near Fault ◽  
Frame Element ◽  
Near Fault Earthquakes

Abstract An advantage bidirectional sloped rolling type isolation device composed of multiple rollers in both orthogonal-in-plane directions is studied in this research. The analytical model of a single direction of roller bearing (RB) system is extended to a two-direction RB system. Also, a 3D linear-elastic frame element to build the finite element model is used to incorporate the response of the building model. Several experimental tests of a physical building model with and without an RB system are used to validate the numerical model. The model is used to assess the nonlinear response history analysis of a four-story multi-column building system with two different physical properties that represent buildings with low and high lateral stiffness when subjected to pairs of scaled near-fault earthquake records. The effect of the angle of inclination of bearing plates in the range of 1.0o to 4.0o and sliding friction force is also investigated in a parametric analysis to evaluate the performance of RB with supplementary damping mechanisms ranging from 0.0 to 0.5N/kg, i.e., friction force normalized with the structure mass. Results show that the proposed bi-directional RB system is suitable for reducing the seismic response of rigid and flexible multi-column structures. In particular, the RB system reduces structure acceleration responses by 5–85% in the flexible structure and 86–96% in the rigid structure. Furthermore, an angle of inclination of bearing plates greater than or equal to 3.0o is an advantage to ensure the self-centering capacity.

scholarly journals New Equivalent Linear Impact Model for Simulation of Seismic Isolated Structure Pounding against Moat Wall

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Yang Liu ◽  
Wen-Guang Liu ◽  
Xin Wang ◽  
Wen-Fu He ◽  
Qiao-Rong Yang
Keyword(s):  
Numerical Analysis ◽  
Structural Response ◽  
Impact Response ◽  
Impact Behavior ◽  
Impact Model ◽  
Near Fault ◽  
Equivalent Linear ◽  
Proposed Model ◽  
Voigt Model ◽  
Near Fault Earthquakes

Base-isolated buildings subjected to extreme earthquakes or near-fault pulse-like earthquakes can exceed their design gap distance and impact against the surrounding moat wall. Based on equating energy dissipation and maximum collision compression deformation of isolated structure with the Hertz-damp model and Kevin-Voigt model in the process of collision, an equivalent linear impact model (ELIM) is proposed to better predict impact response of seismic isolated structure. The formula of the equivalent linear stiffness of ELIM is theoretically derived. The effectiveness of ELIM is verified by comparing the results of numerical analyses with the results of pounding experiments. Four near-fault earthquakes are selected to validate rationality and accuracy of the proposed model using numerical analysis. The results indicate that the proposed linear model can nearly capture impact behavior of isolated structure in simulating the pounding-involved structural response.

scholarly journals Horizontal-Vertical-Rocking Coupled Response Analysis of Vertical Seismic Isolated Structure under Near-Fault Earthquakes

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Dewen Liu ◽  
Yafei Zhang ◽  
Sitong Fang ◽  
Yang Liu
Keyword(s):  
Seismic Isolation ◽  
Damping Ratio ◽  
Vertical Displacement ◽  
Response Analysis ◽  
Isolation System ◽  
Vertical Stiffness ◽  
Near Fault ◽  
Isolated Structures ◽  
Nonlinear Dynamic Analyses ◽  
Near Fault Earthquakes

For vertical isolated structures with excessive vertical eccentricity for mass and vertical stiffness, horizontal-vertical-rocking response needs to be better understood for vertical isolated structures located in near-fault areas, where long-period velocity pulse can be produced. In this study, a seismic isolation system including quasizero stiffness (QZS) and vertical damper (VD) is used to control near-fault (NF) vertical earthquakes. The responses of horizontal-vertical-rocking coupling base-isolated structure including quasizero stiffness (QZS) and vertical damper (VD) subjected to NF horizontal and vertical ground motions are investigated. Nonlinear dynamic analyses are conducted to study the effects of essential parameters such as isolation system eccentricity, static equilibrium position, vertical isolation period, and vertical damping ratio on seismic responses of vertical isolated structure. It is found that increasing vertical period and damping ratio causes the vertical isolated structures to behave well in reducing rocking responses of structure. The effect of horizontal-vertical-rocking coupling on vertical seismic isolation efficiency is insignificant. The vertical seismic isolation remains effective as compared to the system supported on rubber bearings. The vertical damping can significantly control the vertical displacement and rocking moment.

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