• 지구물리와물리탐사
• /
• 제7권4호
• /
• pp.245-250
• /
• 2004

단일 채널 해양 탄성파탐사 자료의 2차원 탄성파 단면도에 수평거리 보정을 적용하여 탄성파 단면도의 수평축을 거리 단위로 표현하였다. 수평축을 거리 단위로 표시함으로써 탐사선의 운항 속력이 변할 경우 나타나는 수평 거리 왜곡 현상을 상당히 해소할 수 있었다. 수평거리 보정을 위하여 탄성파 자료의 각 트레이스에 저장된 GPS 위치 정보와 자료 취합 윈도우를 이용하였다. 자료 취합 윈도우의 최소 길이는 탐사선의 속력과 발파 간격에 의해 결정하였으며, 최대 길이는 1차 프레넬대 반경을 이용하여 결정하였다. 자료 취합 윈도우의 길이를 결정함에 있어 수평 해상도와 중합의 효과를 동시에 고려하였다. 수평거리 보정 과정을 적용하여 실제 지층구조와 유사하다고 생각되는 2차원 탄성파 단면도를 작성할 수 있었다.

• Earthquakes and Structures
• /
• 제14권4호
• /
• pp.337-347
• /
• 2018

This paper presents some shaking table tests conducted on a 1/4-scaled model with 5-story steel reinforced concrete (SRC) spatial frame with irregular section columns under a series of base excitations with gradually increasing acceleration peaks. The test frame was subjected to a sequence of seismic simulation tests including 10 white noise vibrations and 51 seismic simulations. Each seismic simulation was associated with a different level of seismic disaster. Dynamic characteristic, strain response, acceleration response, displacement response, base shear and hysteretic behavior were analyzed. The test results demonstrate that at the end of the loading process, the failure mechanism of SRC frame with irregular section columns is the beam-hinged failure mechanism, which satisfies the seismic code of "strong column-weak beam". With the increase of acceleration peaks, accumulated damage of the frame increases gradually, which induces that the intrinsic frequency decreases whereas the damping ratio increases, and the peaks of acceleration and displacement occur later. During the loading process, torsion deformation appears and the base shear grows fast firstly and then slowly. The hysteretic curves are symmetric and plump, which shows a good capacity of energy dissipation. In summary, SRC frame with irregular section columns can satisfy the seismic requirements of "no collapse under seldom earthquake", which indicates that this structural system is suitable for the construction in the high seismic intensity zone.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
• /
• pp.479-484
• /
• 2000

In this study, optimal design of reinforced concrete piers under seismic load is numerically investigated. Object function is the area of the concreate-section. Design variables are the total area of reinforcement and concrete-section dimension(Circular section diameter). Constraints of the design strength of the column, longitudinal reinforcement ratio and lower and upper bounds on the design variables are imposed. The reinforcement concrete column is analysed and designed by the Ultimated Strength Design method and load combination involving dead, live, wind and seismic load is used. For numerical optimization, ADS(Garret N, Vanderplaats_ routine is used. From the result of numerical examples, the concrete-section dimension was reduced, but longitudinal reinforcement was not changed. The results show that confinement reinforcement was reduced and confinement reinforcement spacing is increased. The higher strength of reinforcement used, the more concrete-section area was reduced.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
• /
• pp.327-334
• /
• 2000

The seismic performance evaluation of the existing non-seismic detailed RC piers has risen as urgent task for rational and cost-effective seismic retrofitting works as well as development of new seismic design concept. The scale model test has been conducted to investigate nonlinear behavior characteristics and the seismic performance of existing piers with lap-spliced longitudinal reinforcements in the plastic hinge zone which are of the solid circular and the hollow rectangular section. The lap splice in this zone is found to cause premature bond failure. The experimental results show very poor seismic performance of circular section pier but relatively large ductility of the rectangular one.

• Steel and Composite Structures
• /
• 제23권1호
• /
• pp.17-29
• /
• 2017

The seismic performance of steel beam to concrete-encased composite column with unsymmetrical steel section joints is investigated and reported within this paper. Experimental and analytical evaluation were conducted on a total of 8 specimens with T-shaped and L-shaped steel section under lateral cyclic loading and axial compression. The test parameters included concrete strength, stirrup ratio and axial compression ratio. The response of the specimens was presented in terms of their hysterisis loop behavior, stress distribution, joint shear strength, and performance degradation. The experiment indicated good structural behavior and good seismic performance. In addition, a three-dimensional nonlinear finite-element analysis simulating was conducted to simulate their seismic behaviors. The finite-element analysis incorporated both bond-slip relationship and crack interface interaction between steel and concrete. The results were also compared with the test data, and the analytical prediction of joint shear strength was satisfactory for both joints with T-shaped and L-shaped steel section columns. The steel beam to concrete-encased composite column with unsymmetrical steel section joints can develop stable hysteretic response and large energy absorption capacity by providing enough stirrups and decreased spacing of transverse ties in column.

• Steel and Composite Structures
• /
• 제19권6호
• /
• pp.1561-1580
• /
• 2015

No significant improvement has been observed on the seismic performance of the ordinary steel reinforced concrete (SRC) columns compared with the reinforced concrete (RC) columns mainly because I, H or core cross-shaped steel cannot provide sufficient confinement for core concrete. Two improved SRC columns by constructing with new-type section steel were put forward on this background: a cross-shaped steel whose flanges are in contact with concrete cover by extending the geometry of webs, and a rotated cross-shaped steel whose webs coincide with diagonal line of the column's section. The advantages of new-type SRC columns have been proved theoretically and experimentally, while construction measures and seismic behavior remain unclear when the new-type columns are joined onto SRC beams. Seismic behavior of SRC joints with new-type section steel were experimentally investigated by testing 5 specimens subjected to low reversed cyclic loading, mainly including the failure patterns, hysteretic loops, skeleton curves, energy dissipation capacity, strength and stiffness degradation and ductility. Effects of steel shape, load angel and construction measures on seismic behavior of joints were also analyzed. The test results indicate that the new-type joints display shear failure pattern under seismic loading, and steel and concrete of core region could bear larger load and tend to be stable although the specimens are close to failure. The hysteretic curves of new-type joints are plumper whose equivalent viscous damping coefficients and ductility factors are over 0.38 and 3.2 respectively, and this illustrates the energy dissipation capacity and deformation ability of new-type SRC joints are better than that of ordinary ones with shear failure. Bearing capacity and ductility of new-type joints are superior when the diagonal cross-shaped steel is contained and beams are orthogonal to columns, and the two construction measures proposed have little effect on the seismic behavior of joints.

• 한국재난정보학회 논문집
• /
• 제15권4호
• /
• pp.626-633
• /
• 2019

연구목적 : 동일한 단면 2차 모멘트를 갖는 곡선 거더의 형상 변화에 따른 곡선 교량의 확률론적 안전성 평가인 지진 취약도 평가를 수행하고자 한다. 연구방법 : I, T, Box Shape 단면을 갖는 곡선 교량을 유한 요소 모델로 구축하였으며 경주 및 포항지진을 포함하여 24개의 입력지진을 적용하여 지진 취약도 평가를 수행하였다. 연구결과 : 거더의 응력에 대한 지진 취약도의 경우 T-Shpae 거더에서 가장 큰 파괴확률이 나타났으며 수평변위에 대한 지진 취약도의 경우 3개의 곡선 교량에서 비슷하게 발생하는 것으로 나타났다. 결론 : 3개의 곡선 교량에 대한 지진 취약도 분석을 수행하였으며 비틀림 저항이 가장 큰 Box-Shape 거더의 파괴확률이 가장 낮은 것으로 나타났다. 추후 연구에서는 추가적인 매개변수를 고려하여 지진 취약도 평가를 수행하고자한다.

• Earthquakes and Structures
• /
• 제8권3호
• /
• pp.779-799
• /
• 2015

The slosh height and the possibility of water spill from rectangular Spent Fuel Storage Bays (SFSB) and Tray Loading Bays (TLB) of Nuclear power plant (NPP) are studied during 0.2 g, Safe Shutdown Earthquake (SSE) level of earthquake. The slosh height obtained through Computational Fluid dynamics (CFD) is compared the values given by TID-7024 (Housner 1963) and American concrete institute (ACI) seismic codes. An equivalent amplitude method is used to compute the slosh height through CFD. Numerically computed slosh height for first mode of vibration is found to be in agreement the codal values. The combined effect in longitudinal and lateral directions are studied separately, and found that the slosh height is increased by 24.3% and 38.9% along length and width directions respectively. There is no liquid spillage under SSE level of earthquake data in SFSB and TLB at convective level and at free surface acceleration data. Since seismic design codes do not have guidelines for combined excitations and effect of higher modes for irregular geometries, this CFD procedure can be opted for any geometries to study effect of higher modes and combined three directional excitations.

• 한국강구조학회 논문집
• /
• 제20권6호
• /
• pp.829-838
• /
• 2008

국내 현실에 적합한 내진 접합부 상세 개발과 평가를 위하여 국내 중저층 철골건물에 적용되는 단면을 갖는 보와 기둥으로 구성 된 접합부 실험체를 선정하여 반복재하 실험을 수행하였다. 실험변수는 접합부 형식과 강종이며 새로 개발된 내진용 형강(SHN490)과 기존 형강 (SM490)의 성능 차이를 비교하였다. 소재인장시험결과에 의하면 SHN490 형강의 항복강도와 인장강도의 분포는 SM490형강의 분포보다 균일한 것으로 평가되었다. 접합부 실험체의 용접부에서의 취성파괴는 관찰되지 않았고 소정의 소성변형 능력을 발휘한 후 보 플랜지의 열영향부나 용 접접근공의 응력집중부위에서 파단이 발생하였다. 동일한 강종으로 구성된 실험체의 경우, 보의 웨브가 볼트에 의하여 기둥에 연결된 접합부 (WUF-B)보다는 용접에 의하여 연결된 접합부(WUF-W)의 회전과 에너지 소산능력이 더 컸다. 또한 동일한 접합부 형식의 실험체에서는 SM490 형강으로 구성된 실험체보다는 SHN490 실험체의 회전과 에너지 소산능력이 더 컸다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
• /
• pp.879-884
• /
• 2002

The objective of this study is to investigate the seismic capacity of the non-seismically detailed RC bridge piers before and after applying a seismic retrofitting method using stainless steel wire mesh. Total nine circular section RC piers were constructed. Different lap splice longitudinal reinforcement details were adapted for four specimens and various types of stainless steel wire mesh were applied for the remaining five specimens. Harmonic cyclic lateral load was applied on each specimen under a constant axial load. The test results indicated that the existing circular piers have low seismic capacity while the stainless steel wire mesh retrofitting method improves the seismic capacity considerably. In addition, test results revealed that the circular section piers could have a considerable amount of ductility if longitudinal bars are not lap-spliced in potential plastic hinge zone. Based on this experimental study it could be concluded that the seismic performance, that is ductility and energy absorption capacity, of the non-seismically detailed RC bridge piers would be increased by applying the stainless steel wire mesh seismic retrofitting method.