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 Influence of Elastomeric Bearings in Tension on the Seismic Performance of Base-Isolated r.c. Buildings

2020 ◽  
Vol 11 (1) ◽  
pp. 82
Author(s):  
Fabio Mazza ◽  
Mirko Mazza
Keyword(s):  
Base Isolation ◽  
Nonlinear Models ◽  
Vertical Component ◽  
Computer Code ◽  
Nonlinear Phenomena ◽  
Isolation System ◽  
Elastomeric Bearings ◽  
Near Fault ◽  
Base Isolation System ◽  
Near Fault Earthquakes

Elastomeric bearings are commonly used in base-isolation systems to protect the structures from earthquake damages. Their design is usually developed by using nonlinear models where only the effects of shear and compressive loads are considered, but uncertainties still remain about consequences of the tensile loads produced by severe earthquakes like the near-fault ones. The present work aims to highlight the relapses of tension on the response of bearings and superstructure. To this end, three-, seven- and ten-storey r.c. framed buildings are designed in line with the current Italian seismic code, with a base-isolation system constituted of High-Damping-Rubber Bearings (HDRBs) designed for three values of the ratio between the vertical and horizontal stiffnesses. Experimental and analytical results available in literature are used to propose a unified nonlinear model of the HDRBs, including cavitation and post-cavitation of the elastomer. Nonlinear incremental dynamic analyses of the test structures are carried out using a homemade computer code, where other models of HDRBs considering only some nonlinear phenomena are implemented. Near-fault earthquakes with comparable horizontal and vertical components, prevailing horizontal component and prevailing vertical component are considered as seismic input. Numerical results highlight that a precautionary estimation of response parameters of the HDRBs is attained referring to the proposed model, while its effects on the nonlinear response of the superstructure are less conservative.

scholarly journals A comparative study of base isolation devices in light rail transit structure featured with lead rubber bearing and friction pendulum system

2018 ◽  
Vol 195 ◽  
pp. 02013
Author(s):  
Santi Nuraini ◽  
Asdam Tambusay ◽  
Priyo Suprobo
Keyword(s):  
Seismic Isolation ◽  
Time History ◽  
Light Rail ◽  
Rail Transit ◽  
Light Rail Transit ◽  
Pendulum System ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Friction Pendulum ◽  
Friction Pendulum System

Advanced nonlinear analysis in light rail transit (LRT) structures has been undertaken to examine the influence of seismic isolation devices for reducing seismic demand. The study employed the use of two types of commercially available bearings, namely lead rubber bearing (LRB) and friction pendulum system (FPS). Six LRT structures, designed to be built in Surabaya, were modelled using computer-aided software SAP2000, where each of the three structures consisted of three types of LRB and FPS placed onto the pier cap to support the horizontal upper-structural member. Nonlinear static pushover and dynamic time history analysis with seven improved ground motion data was performed to gain improved insights on the behavioural response of LRT structures, allowing one to fully understand the supremacy of seismic isolations for protecting the structure against seismic actions. It is shown that both devices manage to isolate seismic forces, resulting in alleviation of excessive base shear occurring at the column. In addition, it is noticeable that the overall responses of LRB and FPS shows marginal discrepancies, suggesting both devices are interchangeable to be used for LRT-like structures.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 6 — Scaled Tests to Obtain Basic Characteristics of Lead Rubber Bearing

2014 ◽  
Author(s):  
Tsutomu Hirotani ◽  
Ryota Takahama ◽  
Masaki Yukawa ◽  
Hiroshi Hibino ◽  
Yuji Aikawa ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Loading Test ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Basic Characteristics ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Hysteresis Characteristics

This paper provides a series comprising the “Development of Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. Part 6 presents scaled tests for Lead Rubber Bearing (LRB) newly developed for this project. Following tests are performed to obtain the basic characteristics of LRB,. (1) Horizontal and Vertical Simultaneous Loading Test: LRBs with diameter of 250mm are tested dynamically under simultaneous axial and lateral loading. The hysteresis characteristics is not changed under compressive load although it is changed under tensile load. (2) Basic Break Test: LRBs with a diameter of 800mm are tested statically under various combinations of axial and lateral forces. The hysteresis characteristics model of LRB is determined by this test. It is confirmed that the breaking strain of LRB under compression load exceeds 450%. (3) Horizontal Hardening and Vertical Softening Test: For LRBs with a diameter of 1200 mm, 75% scale of actual LRB are tested statically for horizontal hardening and vertical softening regions. It is confirmed that the hysteresis model which is developed by smaller LRBs is applicable to these large scale models.

Study of Vertical Seismic Isolation of Self-Anchored Cable-Stayed Suspension Bridge Based on Lead Rubber Bearing

2014 ◽  
Vol 904 ◽  
pp. 520-523
Author(s):  
Feng Miao
Keyword(s):  
Seismic Isolation ◽  
Suspension Bridge ◽  
Stiffness Analysis ◽  
Seismic Input ◽  
Damping Characteristics ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Yield Force

Based on the background of Dalian Bay Cross-Sea Bridge project, some plans with settings of lead-rubber bearing among side pier, tower and stiffening girder have been analyzed under vertical seismic input using the favorable shearing property of laminated rubber, damping characteristics of lead and reasonable parameters (yield force and stiffness). Analysis results show that the displacement of controlling node and force of controlling section have been reduced.

A study on seismic isolation of building used LRB

2020 ◽  
Vol 6 (2) ◽  
pp. 52
Author(s):  
Muhammet Yurdakul ◽  
Mehmet Burak Yıldız
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Dynamic Loads ◽  
Isolation System ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Earthquake Design ◽  
Base Isolation System ◽  
Internal Forces ◽  
Storey Building

Base isolation system with lead rubber bearing (LRB) is commonly used to prevent structure against to damage of earthquake. Design of LRB system is detailed in this study. The isolated building with LRB design according to Uniform Building Code (UBC-97) and fixed building were examined. The six-storey building with LRB and fixed building were modelled in SAP2000 with the same dynamic loads. The relative floor displacement and internal forces of the seismic isolated and fixed building are compared. In addition, transverse and longitudinal reinforcement of any axis of seismic isolated and fixed building are compared. Analyse results showed that effectiveness of using seismic isolation system on building. The weight of longitudinal and transverse reinforcement of isolated building is smaller than fixed building about 36%, 40% respectively.

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