• 전산구조공학
• /
• 제21권4호
• /
• pp.61-66
• /
• 2008

• Journal of Mechanical Science and Technology
• /
• 제18권1호
• /
• pp.20-29
• /
• 2004

This paper proposes a new type of bearing system. In this study, a method for design of on elastomeric bearing system and its mechanical property analysis are carried. Experimental and theoretical studies of the elastomeric bearings with fiber reinforcement were proved effective new lightweight bearing system. The fibers in the bearings for isolation are assumed to be flexible in extension, in contrast to the steel plates in the conventional bearing system. Several kinds of bearing systems in the form of long strips are designed, fabricated and tested. The results suggest that it is possible to produce the economical and effective fiber-reinforced elastomeric bearing that matches the behavior of a steel-reinforced bearing. Feasibility and advantages of the proposed bearings are illustrated by the application of the analytic procedure to the structure system. Results obtained here are reported to be an efficient approach with respect to bearing system and design of bearing against shock absorbing system when compared with other conventional one.

• Earthquakes and Structures
• /
• 제6권2호
• /
• pp.127-140
• /
• 2014

Laminated rubber bearing is very popular base isolation of earthquake engineering pertaining to the passive structural vibration control technologies. Rubber used in fabricating NRB and LRB can be easily attacked by various environmental factors such as oxygen, heat, light, dynamic strain, and organic liquids. Among these factors, this study carried out thermal aging test to investigate the effect of thermal aging on the mechanical properties of laminated rubber bearings in accelerated exposure condition of $70^{\circ}C$ temperature for 168 hours. The compressive-shear test was carried out to identify the variation of compressive and shear properties of the rubber bearings before and after thermal aging. In contrast to tensile strength and elongation tests, the hardness of rubber materials showed the increasing tendency dependent on exposure temperature and period. Based on the test results, the property changes of rubber bearing mainly aged by heat are quantitatively presented.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
• /
• pp.236-243
• /
• 1999

A comparative study on aseismatic performances of various base isolation systems for the multi-span continuous bridge is carried out. Several leading base isolation systems the LRB system the RF system the R-FBI system and the EDF system are considered, The displacement of the deck the deformation of the upper ends of the piers the shear force and the bending moment of the lower ends of the piers are obtained by using the accelerograms of the N00W component of El Centro earthquake(1940) and the N90W component of Mexico City earthquake(1985) Nonlinear time-history analysis is carried out. comparisons of the results with the conventional bearing show that the base isolation systems are very effective in reducing the forces transmitted to the superstructures. Furthermore the results also show that the friction-type base isolation systems are less sensitive to unexpected variations in frequency content of the ground acceleration. The R-FBI system shows a good aseismatic performance comparing with other base isolation systems.

• Structural Engineering and Mechanics
• /
• 제38권3호
• /
• pp.361-384
• /
• 2011

Earlier studies on hollow-circular rubber bearings, all of which are conducted for steel-reinforced bearings, indicate that the hole presence not only decreases the compression modulus of the bearing but also increases the maximum shear strain developing in the bearing due to compression, both of which are basic design parameters also for fiber-reinforced rubber bearings. This paper presents analytical solutions to the compression problem of hollow-circular fiber-reinforced rubber bearings. The problem is handled using the most-recent formulation of the "pressure method". The analytical solutions are, then, used to investigate the effects of reinforcement flexibility and hole presence on bearing's compression modulus and maximum shear strain in the bearing in view of four key parameters: (i) reinforcement extensibility, (ii) hole size, (iii) bearing's shape factor and (iv) rubber compressibility. It is shown that the compression stiffness of a hollow-circular fiber-reinforced bearing may decrease considerably as reinforcement flexibility and/or hole size increases particularly if the shape factor of the bearing is high and rubber compressibility is not negligible. Numerical studies also show that the existence of even a very small hole can increase the maximum shear strain in the bearing significantly, which has to be considered in the design of such annular bearings.

• Smart Structures and Systems
• /
• 제16권4호
• /
• pp.701-723
• /
• 2015

Friction isolators are one of the most important types of bearings used to mitigate damages of earthquakes. The adaptive behavior of these isolators allows them to achieve multiple levels of performances and predictable seismic behavior during different earthquake hazard levels. There are three main types of friction isolators. The first generation with one sliding surface is known as Friction Pendulum System (FPS) isolators. The double concave friction pendulum (DCFP) with two sliding surfaces is an advanced form of FPS, and the third one, with fully adaptive behavior, is named as triple concave friction pendulum (TCFP). The current study has been conducted to investigate and compare seismic responses of these three types of isolators. The structure is idealized as a two-dimensional single degree of freedom (SDOF) resting on isolators. The coupled differential equations of motion are derived and solved using state space formulation. Seismic responses of isolated structures using each one of these isolators are investigated under seven near fault earthquake motions. The peak values of bearing displacement and base shear are studied employing the variation of essential parameters such as superstructure period, effective isolation period and effective damping of isolator. The results demonstrate a more efficient seismic behavior of TCFP isolator comparing to the other types of isolators. This efficiency depends on the selected effective isolation period as well as effective isolation damping. The investigation shows that increasing the effective isolation period or decreasing the effective isolation damping improves the seismic behavior of TCFP compared to the other isolators. The maximum difference in seismic responses, the base shear and the bearing displacement, for the TCFP isolator are calculated 26.8 and 13.4 percent less than the DCFP and FPS in effective isolation damping equal to10%, respectively.

• Earthquakes and Structures
• /
• 제9권3호
• /
• pp.603-623
• /
• 2015

The scale and nature of the recent earthquakes in the world and the related earthquake disaster index coerce the concerned community to become anxious about it. Therefore, it is crucial that seismic lateral load effect will be appropriately considered in structural design. Application of seismic isolation system stands as a consistent alternative against this hazard. The objective of the study is to evaluate the structural and economic feasibility of reinforced concrete (RC) buildings with base isolation located in medium risk seismic region. Linear and nonlinear dynamic analyses as well as linear static analysis under site-specific bi-directional seismic excitation have been carried out for both fixed based (FB) and base isolated (BI) buildings in the present study. The superstructure and base of buildings are modeled in a 3D finite element model by consistent mass approach having six degrees of freedom at each node. The floor slabs are simulated as rigid diaphragms. Lead rubber bearing (LRB) and High damping rubber bearing (HDRB) are used as isolation device. Change of structural behaviors and savings in construction costing are evaluated. The study shows that for low to medium rise buildings, isolators can reduce muscular amount of base shears, base moments and floor accelerations for building at soft to medium stiff soil. Allowable higher horizontal displacement induces structural flexibility. Though incorporating isolator increases the outlay, overall structural cost may be reduced. The application of base isolation system confirms a potential to be used as a viable solution in economic building design.

• Earthquakes and Structures
• /
• 제4권6호
• /
• pp.587-606
• /
• 2013

The given paper presents a new approach in design of seismic isolation systems of base isolated buildings. The idea is to install not one big size rubber bearing under the columns and/or shear walls, or one by one with certain spacing under the load-bearing walls, but to install a group/cluster of small size bearings, in order to increase the overall effectiveness of the isolation system. The advantages of this approach are listed and illustrated by the examples. Also the results of analyses of some buildings where the approach on installation of clusters of rubber bearings was used in their isolation systems are given for two cases: i) when the analyses are carried out based on the provisions of the Armenian Seismic Code, and ii) when the time history analyses are carried out. Obtained results are compared and discussed. Paper also presents, as an example, detailed analysis and design of the 18-story unique building in one of the residential complexes in Yerevan. Earthquake response analyses of this building were carried out in two versions, i.e. when the building is base isolated and when it is fixed base. Several time histories were used in the analyses. Comparison of the obtained results indicates the high effectiveness of the proposed structural concepts of isolation systems and the need for further improvement of the Seismic Code provisions regarding the values of the reduction factors. A separate section in the paper dedicated to the design of high damping laminated rubber-steel bearings and to results of their tests.

• 한국공간구조학회논문집
• /
• 제19권2호
• /
• pp.109-116
• /
• 2019

In this study, the seismic response is investigated by using a relatively low-rise building under torsion-prone conditions and three seismic loads with change of the location of the seismic isolation system. LRB (Lead Rubber Bearing) was used for the seismic isolator applied to the analytical model. Fixed model without seismic isolation system was set as a basic model and LB models using seismic isolation system were compared. The maximum story drift ratio and the maximum torsional angle were evaluated by using the position of the seismic layer as a variable. It was confirmed that the isolation device is effective for torsional control of planar irregular structures. Also, it was shown that the applicability of the mid-story seismic isolation system. Numerical analyses results presented that an isolator installed in the lower layer provided good control performance for the maximum story drift ratio and the maximum torsional angle simultaneously.

• 한국구조물진단유지관리공학회 논문집
• /
• 제4권3호
• /
• pp.137-144
• /
• 2000

Judging from the occasional occurrences of minor and major earthquakes in Korean peninsula, it is generally considered that Korean peninsula is not located in safe zone from earthquake any more. The worldwide damages from earthquake in public buildings such as bridges are also urging the necessity for an appropriate earthquake proof action. The elastomeric bearings have been used in seismic isolation design of bridges. and elastomeric bearings are quite ideal ones which allow movement and rotation in all directions without restraining superstruture. Within the limits of this study on dynamic behavior of the LBR for seismic isolation design, the reaearch results revealed that the Laminated Rubber Bearing(LRB) is useful in bridges for seismic isolation design. In addition, the relationship between the shape factor and compressive strength is linear. It was also found that the compressive strength gets higher as the shape factor increases.