• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.472-472
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• 2009

The safety of cultural properties, medical treatment and electrical communication equipments in a building was hardly considered against the earthquake induced vibration, while the integrity of the building structure has been taken into account through the resistant earthquake design. This paper presents design of a seismic isolation table for both indoor and outdoor electrical communication equipment. First of all, artificial earthquake waves compatible with floor and ground response spectra for electrical communication equipments are generated using previously recorded seismic waves. Two kinds of one-degree-of-freedom seismic isolation table systems: spring-linear damper and spring-friction damper systems are considered and their responses to artificial earthquake waves are simulated. Design parameter study for two seismic isolation tables are performed through simulations and a seismic isolation table for both indoor and outdoor electrical communication equipment is designed considering the simulation results.

• 한국소음진동공학회논문집
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• 제16권3호
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• pp.307-312
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• 2006

In this study a vibration isolation system with the cradle-type support was designed so as to reduce the transient vibration due to positioning motion of the moving mass on worktable as well as to achieve the desired isolation efficiency on the floor vibration. The design procedure was performed in the two steps. The first step to select appropriate isolators to meet the isolation efficiency, and the second step is to reduce the transient vibration of the worktable by adopting the cradle-type support. After the application of the selected isolators with the cradle-type support to the system it was shown that the required vibration criterion(VC-D) was easily satisfied and that the undesirable transient vibration was reduced remarkably.

• Structural Engineering and Mechanics
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• 제51권2호
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• pp.277-297
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• 2014

Since the isolation bearings undergo large displacements in base-isolated structures, impact with adjacent structures is inevitable. Therefore, in this investigation, the effect of impact on seismic response of isolated structures mounted on double concave friction pendulum (DCFP) bearings subjected to near field ground motions is considered. A non-linear viscoelastic model of collision is used to simulate structural pounding more accurately. 2-, 4- and 8-story base-isolated buildings adjacent to fixed-base structures are modeled and the coupled differential equations of motion related to these isolated systems are solved in the MATLAB environment using the SIMULINK toolbox. The variation of seismic responses such as base shear, displacement in the isolation system and superstructure (top floor) is computed to study the impact condition. Also, the effects of variation of system parameters: isolation period, superstructure period, size of seismic gap between two structures, radius of curvature of the sliding surface and friction coefficient of isolator are contemplated in this study. It is concluded that the normalized base shear, bearing and top floor displacement increase due to impact with adjacent structure. When the distance between two structures decreases, the base shear and displacement increase comparing to no impact condition. Besides, the increase in friction coefficient difference also causes the normalized base shear and displacement in isolation system and superstructure increase in comparison with bi-linear hysteretic behavior of base isolation system. Totally, the comparison of results indicates that the changes in values of friction coefficient have more significant effects on 2-story building than 4- and 8-story buildings.

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

• 한국구조물진단유지관리공학회 논문집
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• 제26권1호
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• pp.39-48
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• 2022

지진 발생 시 방송통신서비스는 현장 구조 및 효과적인 복구 작업에 직결된다. 최근에 다양한 면진장치들이 방송통신설비의 심각한 피해를 방지하기 위하여 건물 층과 방송통신설비의 바닥부 사이에 설치하는 방법이 널리 사용되고 있다. 하지만 긴 고유주기를 가진 건물은 공진현상에 따른 예상치 못한 응답증폭으로 인하여 더 큰 피해가 발생할 수도 있다. 따라서 본 연구에서는 두 개의 면진장치를 선정 후 중층, 고층건물의 해석적, 실험적 연구를 통하여 면진장치가 바닥부에 설치된 방송통신설비의 내진 안전성을 평가를 목표로 한다. 해석적 연구를 수행하여 가진 시 중층, 고층건물 최고층의 저주파수 영역대의 동적응답을 확인하였다. 또한 해석적 연구에서 확보한 층응답을 바닥부에 면진장치가 설치된 방송통신 설비를구비하여 실증 실험을 통해 내진안정성을 평가하였다.

• Structural Engineering and Mechanics
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• 제40권3호
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• pp.315-334
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• 2011

Seismic isolated building structures are examined in this study. The triple concave friction pendulum (TCFP) is used as a seismic isolation system which is easy to be manufactured and enduring more than traditional seismic isolation systems. In the TCFP, take advantage of weight which pendulum carrying and it's geometry in order to obtain desirable result of seismic isolation systems. These systems offer advantage to buildings which subject to severe earthquake. This is result of damping force of earthquake by means of their internal constructions, which consists of multiple surfaces. As the combinations of surfaces upon which sliding is occurring change, the stiffness and effective friction change accordingly. Additionally, the mentioned the TCFP is modeled as of a series arrangement of the three single concave friction pendulum (SCFP) bearings. A two dimensional- and eight- story of a building with and without isolation system are used in the time history analysis in order to investigate of the effectiveness of the seismic isolation systems on the buildings. Results are compared with each other to emphasize efficiency of the TCFP as a seismic isolation device against the other friction type isolation system like single and double concave surfaces. The values of the acceleration, floor displacement and isolator displacement obtained from the results by using different types of the isolation bearings are compared each other. As a result, the findings show that the TCFP bearings are more effective devices for isolation of the buildings against severe earthquakes.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1776-1781
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• 2008

To reduce interior noise of running vehicles, a floating floor construction has been widely used in recent railway industry. Among the key factors of the floating floor design, dynamic stiffness is of most important in acoustical point of view. Sometimes hard rubber type supports have often been selected due to the other design constraints such as heavy load condition, durability of rubber element and its cost etc., even though it seems like the softer support, the better isolation of noise and vibration. In this paper two representative floor supports have been considered to evaluate their effectiveness in interior noise contribution: one is a soft rubber and another is a relatively hard one. From the measured dynamic stiffness of the specimens, equivalent stiffness of actual floating floor has been derived to use in the analytical models. Calculated air-borne and structure-borne noise insulation properties of the floating floors have been compared with experiments in prototype car. In full car model interior noise levels of running vehicles have been predicted to quantify the effectiveness of the two different floating support materials and verified through the measured inside noise levels of actual train as well. By comparison with difference of running noise levels two materials for floor support can be investigated quantitatively so that it could be applied in floating floor design.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.383-386
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• 2005

Low frequency heavy-weight impact noise is the most irritating noise in Korean high-rise reinforced concrete apartment buildings. This low frequency noise is generated by foot traffic due to the fact that Koreans do not wear shoes at home. The transmission of the noise is facilitated by a load bearing wall structural system without beams and columns which is used in these buildings. In order to control low frequency heavy-weight impact noise, floating floors using isolation materials such as glass-wool mat and poly-urethane mat are used. However, it was difficult to control low frequency heavy-weight impact sound using isolation material. In this study, reinforcement of concrete slab using beams and plate was conducted. Using the FEM analysis, the effect of concrete slab reinforcement using FRP(fiber-glass reinforced plastic) on the bang machine impact vibration acceleration level and sound were conducted at the standard floor impact sound test building. The $3{\sim}4dB$ floor impact vibration acceleration level and impact sound pressure level were reduced and the natural frequency of slabs were changed.

• 대한조선학회 특별논문집
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• 대한조선학회 2009년도 특별논문집
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• pp.93-96
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• 2009

Foundation structure for the main engine heavy spare parts in the engine room is susceptible to resonance problem due to outfitting weight. In addition the deck floor has a large opening for the main engine installation and maintenance, which further weakens the foundation structure. To reinforce the weak structure, two types of approaches have been used; 1) insert an H-pillar below or above the floor and 2) increase the stiffener size. In this paper, the H-pillar approach is used to solve the vibration problem of the foundation structure in the engine room opening area. A commercial program is used to analyze the vibration problem ad to find the location and the size of the H-pillar. Modal test at the quay and on-board vibration measurement during the sea trial have confirmed the validity of inserting an H-pillar below the floor.

• 한국공간구조학회논문집
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• 제19권4호
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• pp.27-34
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• 2019

Spatial structure does not have columns and walls installed inside, so they have a large space. There are upper structure and substructure supporting them. The response of seismic loads to the upper structure may be increased or decreased due to the effects of the substructure. Therefore, in this study, the seismic response of the upper structure and the floor response spectrum of the substructure were compared and analyzed according to the height of the substructure in the spatial structure where the LRB was installed. As a result, the possibility of amplification of response was confirmed as seismic waves passed though the substructure, which is likely to increase the response of the upper structures.