• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.401-406
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• 2013

This paper presents experimental evaluation of IRE (isolation roller bearing) seismic isolation device. From the combination of base isolation on the IRE system displacement response spectrum and acceleration response spectrum, the compressive strength and the coefficient of friction experiments. Also the IRE system is evaluated by environment test according to KS standards. Both the resonance and seismic experiments using a combination of the IRE and Natural Rubber Bearing (NRB) are performed in order to analyze the seismic isolation of the IRE system dynamic characteristics. For the given load and exciting frequency, the resonant frequency becomes lower, but the resonant magnification remains to be same. However, it is shown that when we consider the IRE only, the vibration on the table with the horizontal movement and the independent horizontal displacement due to the rolling motion of the plate and roller are significantly reduced. This result verifies that the proposed optimal design method of the IRE system is very effective.

• Earthquakes and Structures
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• 제19권4호
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• pp.261-272
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• 2020

Recent severe earthquakes in and around the vital public places worldwide indicate the severe vulnerability of ground excitation to be assailed. Reducing the effect of seismic lateral load in structural design is an important conception. Essentially, seismic isolation is required to shield the superstructure in such a way that the building superstructure would not move when the ground is shaking. This study explores the effectiveness, design, and practical feasibility of base isolation systems to reduce seismic demands on buildings of varying elevations. Thus, static and dynamic analyses were conducted based on site-specific bi-directional earthquakes for base-isolated as well as fixed-based buildings. Remarkably, it was discovered that isolators used in low-rise to high-rise structures tend to significantly decrease the structural responses of seismic prone buildings. The higher allowable horizontal displacement induces structural flexibility and ensure good structural health of the building stories. Reinforcement from vertical and horizontal members can be reduced in significant amounts for BI buildings. Thus, although incorporating base isolators increases the initial outlay, it considerably diminishes the total structural cost.

• 한국기계가공학회지
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• 제17권1호
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• pp.122-129
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• 2018

This study conducted a seismic qualification analysis of small savonius style vertical axis wind turbine(VAWT) using finite element method(FEM). The modal analysis was performed on the wind turbine structure to check the occurrence of resonance caused by the rotation of gearbox and windmill blades. Next, it conducted a seismic response spectrum analysis due to horizontal and vertical seismic load of required response spectrum of safe shutdown earthquake with 5 % damping(RRS/SSE 5%) of KS C IEC 61400 and conducted a static analysis due to deadweight and wind load. The total maximum stress of the VAWT structure was calculated by adding the maximum stresses due to each load case using the square root of the sum of the squares(SRSS) method. Finally, the structural safety of the VAWT structure was verified by comparing the total maximum stress and the allowable stress.

• Structural Engineering and Mechanics
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• 제78권3호
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• pp.269-280
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• 2021

Reinforced concrete (RC) structural walls with L-shaped sections are commonly used in RC buildings. The walls are often expected to sustain biaxial load and Unsymmetrical bending in an earthquake event. However, there currently exists limited experimental evidence regarding their seismic behaviour in these lateral loading directions. This paper makes experimental and numerical investigations to these walls behaviours. Experimental evidences are presented for four L-shaped wall specimens which were tested under simulated seismic load from different lateral directions. The results highlighted some distinct behaviour of L-shaped walls sustaining Unsymmetrical bending relating to their seismic performance. First, due to the Unsymmetrical bending, out-of-plane reaction forces occur for these walls, which contribute to accumulation of the out-of-plane deformations of the wall, especially when out-of-plane stiffness of the section is reduced by horizontal cracks in the cyclic load. Secondly, cracking was found to affect shear centre of the specimens loaded in the Unsymmetrical bending direction. The shear centre of these specimens distinctly differs in the flange in the positive and negative loading direction. Cracking of the flange also causes significant warping in the bottom part of the wall, which eventually lead to out-of-plane buckling failure.

• 한국전산구조공학회논문집
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• 제24권2호
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• pp.201-210
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• 2011

이 연구에서는 깊은보-내부기둥 접합부의 내진성능평가를 위한 비선형 유한요소해석 기법을 제시하였다. 사용된 프로그램은 철근콘크리트 구조물의 해석을 위한 RCAHEST이다. 깊은보-내부기둥 접합부의 강도, 연성도 등 거동특성을 파악하기 위한 반복횡하중 실험을 수행하였다. 실험의 변수로는 축력과 횡방향 철근량을 정하였다. 이 연구에서는 깊은보-내부기둥 접합부의 내진성능평가를 위해 제안한 해석기법을 신뢰성 있는 실험결과와 비교하여 그 타당성을 검증하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제3권3호
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• pp.139-147
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• 1999

Six reinforced concrete shear wall, constructured with fully rigid, slit, and infilled types, were tested under both vertical and cyclic loadings. Experimental programs were carried out to evaluate the seismic performance of such test specimens, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility, under load reversals. All the specimens were modeled in one-third scale size. Based on the test results, the following conclusions can be made. For the diagonal reinforced slit and infilled shear wall specimens, it was found that the failure mode shows very effective crack control and crushing due to slippage prevention of boundary region and reduction of diagonal tension rathar than the brittle shear and diagonal tension failure. The ductility of specimens designed by the diagonal reinforcement for the slit and infilled shear wall was increased 1.72~1.81 times in comparison with the fully rigid shear wall frame. Maximum horizontal load-carrying capacity of specimens designed by the diagonal reinforcement ratio the slit and infilled shear wall was increased respectively by l.14 times and l.49 times in comparison with the standard fully rigid shear wall frame.

• Coupled systems mechanics
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• 제11권5호
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• pp.373-387
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• 2022

In this paper,soil-structure interaction effects on the seismic response of multistory frame structure on raft foundation are numerically analyzed. The foundation soil profile is assumed to consists of a clay layer of variable thicknessresting on bedrock. Amodified plane-strain numerical model isformed in the software Plaxis, and both free vibration analysis, and earthquake analysis for a selected ground motion accelerogram are performed. The behavior of the structure is assumed to be linear elastic with Rayleigh viscous damping included. The behavior of the clay layer is modeled with a Hardening soil model with small strain stiffness. The computed results in terms of fundamental period and structural horizontal displacementsfor the case of fixed base and for different thicknesses of clay layer are presented, compared, and discussed.

• Steel and Composite Structures
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• 제13권5호
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• pp.473-487
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• 2012

An experimental study was performed to investigate the seismic performance of steel reinforced concrete (SRC) special-shaped columns. For this purpose, 17 steel reinforced concrete special-shaped column specimens under low-cyclic reversed load were tested, load process and failure patterns of the specimens with different steel reinforcement were observed. The test results showed that the failure patterns of these columns include shear-diagonal compression failure, shear-bond failure, shear-flexure failure and flexural failure. The failure mechanisms and characteristics of SRC special-shaped columns were also analyzed. For different SRC special-shaped columns, based on the failure characteristics and mechanism observed from the test, formulas for calculating ultimate shear capacity in shear-diagonal compression failure and shear-bond failure under horizontal axis and oblique load were derived. The calculated results were compared with the test results. Both the theoretical analysis and the experimental results showed that, the shear capacity of T, L shaped columns under oblique load are larger than that under horizontal axis load, whereas the shear capacity of +-shaped columns under oblique load are less than that under horizontal axis load.

• 한국기계가공학회지
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• 제15권3호
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• pp.21-27
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• 2016

The static and dynamic structural integrity qualification was performed through the seismic analysis of a small-size Savonius-type vertical wind turbine at dead weight plus wind load and seismic loads. The ANSYS finite element program was used to develop the FEM model of the wind turbine and to accomplish static, modal, and dynamic frequency response analyses. The stress of the wind turbine structure for each wind load and dead weight was calculated and combined by taking the square root of the sum of the squares (SRSS) to obtain static stresses. Seismic response spectrum analysis was also carried out in the horizontal (X and Y) and vertical (Z) directions to determine the response stress distribution for the required response spectrum (RRS) at safe-shutdown earthquake with a 5% damping (SSE-5%) condition. The stress resulting from the seismic analysis in each of the three directions was combined with the SRSS to yield dynamic stresses. These static and dynamic stresses were summed by using the same SRSS. Finally, this total stress was compared with the allowable stress design, which was calculated based on the requirements of the KBC 2009, KS C IEC 61400-1, and KS C IEC 61400-2 codes.

• Earthquakes and Structures
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• 제24권6호
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• pp.415-428
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• 2023

Low-cost techniques with seismic isolation performance and excellent resilience need to be explored in the case of rural low-rise buildings because of the limited buying power of rural residents. As an inexpensive and eco-friendly isolation bearing, scrap tire pads (STPs) have the issue of poor resilience. Thus, a seismic isolation system under a column (SISC) integrated with STP needs to be designed for the seismic protection of low-rise rural buildings. The SISC, which is based on a simple exterior design, maintains excellent seismic performance, while the mechanical behavior of the internal STP provides elastic resilience. The horizontal behaviors of the SISC are studied through load tests, and its mechanical properties and the intrinsic mechanism of the reset ability are discussed. Results indicate that the average residual displacement ratio was 24.59%, and the reset capability was enhanced. Comparative experimental and finite element analysis results also show that the load-displacement relationship of the SISC was essentially consistent. The dynamic characteristics of isolated and fixed-base buildings were compared by numerical assessment of the response control effects, and the SISC was found to have great seismic isolation performance. SISC can be used as a low-cost base isolation device for rural buildings in developing countries.