• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.16 no.4
• /
• pp.353-367
• /
• 2003

This paper describes the extension of the numerical model, which was developed to simulate the nonlinear behavior of reinforced concrete (RC) structures subjected to monotonic in plane shear and introduced in the companion paper, to simulate effectively the behavior of RE structures under cyclic loadings. While maintaining all the basic assumptions adopted in defining the constitutive relations of concrete under monotonic loadings, a hysteretic stress strain relation of concrete, which across the tension compression region, is defined. In addition, unlike previous simplified stress strain relations, curved unloading and reloading branches inferred from the stress strain relation of steel considering the Bauschinger effect we used. The modifications of the stress strain relation of steel are also introduced to reflect pinching effect depending on the shear span ratio and an average stress distribution in a cracked RC element. Finally, correlation studies between analytical results and experimental studies are conducted to establish the validity of the proposed model.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.3 no.4
• /
• pp.23-32
• /
• 1999

Behavior of H-beam connections under cyclic loadings is investigated experimentally in this study. The purpose of this study is to study the effect of steel properties and coping shape on the hysteretic behavior of H-beam connections. Five beam-to-column connection specimens were fabricated and tested under cyclic loadings. The load-rotation curves of the beam connections were mainly obtained. Deformation capacity and energy dissipation capacity of the connections are compared each other. The connections fabricated from SS400 showed good deformability and energy dissipation capacity, but those from SM490 showed brittle fracture at the connection. The coping shape at the connections showed a little difference in cyclic behavior.

• Journal of the Korea Concrete Institute
• /
• v.24 no.6
• /
• pp.737-744
• /
• 2012

Hysteretic steel damper has been applied mainly to steel buildings. However, the usage in RC buildings is rapidly increasing recently. In order to apply the steel hysteretic damper in RC buildings, supporting elements of the damper should have sufficient strength and stiffness suitable for transferring damper forces to beams and walls. But due to the inevitable damage in reinforced concrete elements due to cracking, identification of the load transfer mechanism from damper to supporting element and hysteretic characteristics of the supporting element are extremely important in evaluating the damper behavior. Experiments were carried out on connection details between RC walls and supporting elements of the steel plate typed damper such as EaSy damper. The test results showed that fracture patterns of all specimens were almost identical except in the crack number and pattern associated with shear loading condition. Among the specimens, HD-3 shoed a well distributed cracks patterns along with good performance with respect to energy dissipation capacity, stiffness deterioration, and strength degradation.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.32 no.6
• /
• pp.425-434
• /
• 2019

It is important to ensure the seismic safety of pile-bent bridges constructed in areas with thick soft ground consisting of various soil layers against seismic motion in these layers. In this study, several synthetic seismic waves that are compatible with the seismic design spectrum for rock sites were generated, and the ground acceleration history of each soil layer was obtained based on ground analyses. Using these acceleration histories, each soil layer was modeled using equivalent linear springs, and multi-support excitation analyses were performed using the input motion obtained at each soil layer. Due to the nonlinear behavior of the soft soil layers, the intensity of the input ground motion was not amplified, which resulted in the elastic behavior of the bridge. In addition, inputting the acceleration history obtained from a particular layer simultaneously into all the ground springs reduced the response. Therefore, the seismic performance of this type of bridge might be overestimated if multi-excitation analysis is not performed.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.360-360
• /
• 2022

토양수분과 유출 간 관계를 정량화하는 것은 수문 기작 및 유출 발생 과정의 이해를 위한 중요한 정보를 제공한다. 특히, 유출과정의 특성화는 수문 사상에 따른 불포화대 내 토양수 및 토사 손실 제어와 산사태 및 비점오염원 발생 예측을 위해 필수적이다. 유출과정과 관련된 비선형성과 복잡성을 확인하기 위해 토양수분과 유출 사이의 이력 거동이 조사되었다. 특히, 수문 과정 내 이력 현상 구체화를 위해 정성적인 시각적 분류 및 정량적 평가를 위한 이력 지수들이 개발되었다. 정성적인 시각적 분류는 시간에 따라 시계 및 반시계방향으로 다중 루프 형상을 나누는 방식으로 진행되었고, 정량적 평가의 경우 이력 고리(Hysteretic loop) 내 상승 고리(Rising limb)와 하강 고리(Falling limb)의 차이를 기준으로 한 지수로 이력 현상을 특성화하였다. 이전에 제안된 방법론들은 연구자의 판단이 들어가기 때문에 보편적이지 않고 이력 현상을 개발된 지수에 맞춤에 따라 자료 손실이 나타나는 한계가 존재한다. 자료의 손실 없이 불포화대 내 발생 가능한 대표 이력 현상을 자동으로 추출하기 위해 적합한 비지도 학습기반 기계학습 방법론의 제안이 필요하다. 우리 연구에서는 국내 산지 사면에서 강우 사상 동안 다중 깊이(10, 30, 60cm)로 56개의 토양수분 측정지점에서 확보된 토양수분 시계열 자료와 산지 사면 내 위어를 통해 확보된 유출 시계열 자료를 사용하였다. 먼저, 기존에 분류 방법을 기반으로 계절 및 공간특성에 따라 지배적으로 발생하는 토양수분-유출 간 이력 현상을 특성화하였다. 다음으로, 토양수분-유출 간 이력 패턴을 자료 손실 없이 형상화하여 자동으로 데이터베이스화하는 알고리즘을 개발하였다. 마지막으로, 비지도 학습방법을 이용하여 데이터베이스화된 실제 발현 이력 현상 내 확률분포를 최대한 가깝게 추정하는 은닉층을 반복적인 재구성 학습을 통해 구현함으로써 대표 이력 현상 패턴을 추출하였다.

• Proceedings of the Korean Fiber Society Conference
• /
• 1994.10a
• /
• pp.12-13
• /
• 1994

• 건축구조
• /
• v.13 no.3
• /
• pp.31-40
• /
• 2006

구조물의비탄성거동을알아내기위한여러가지의지진해석방법중에서비탄성시간이력해석이가장정확한응답을준다고알려져있지만실제내진설계에서이보다더쉽게비탄성거동을근사적으로파악할수있는방법이능력스펙트럼법(Capacity Spectrum Method: CSM)인데여기서는이방법의기본적인원리를소개하기로한다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.9
• /
• pp.4294-4301
• /
• 2012

The inelastic response characteristics of the standard school buildings depending on selection of hysteresis models and variable earthquakes are studied. Three earthquake records of El-centro, Santa-Monica, Taft in accordance with KBC2009 standard and four inelastic hysteresis models such as Degrading tri-linear model, Clough model, Takeda model, and Modified Takeda model are used. The inelastic response characteristics such as story shear force, story drift ratio, story displacement are reviewed. As results, El-centro earthquake shows large response in transverse direction and Santa Monica earthquake shows larger response in longitudinal direction on the contrary. Taft earthquake shows less variation of story drift ratio and story displacement for all hysteresis models and stable response.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.20 no.1
• /
• pp.72-84
• /
• 2016

The conventional brace system is generally accepted as the lateral load resisting system for steel structures due to efficient story drift control and economic feasibility. But lateral stiffness of the structure decreases when buckling happens to the brace in compression, so that it results in unstable structure with unstable hysteresis behavior through strength deterioration. Buckling restrained brace(BRB) system, in which steel core is confined by mortar/concrete-filled tube, represents stable behavior in the post-yield range because the core's buckling is restrained. So, seismic performance of BRB is much better than that of conventional brace system in point of energy absorption capacity, and it is applied the most in high seismicity regions as damper element. BRBs with various shaped-sections have been developed across the globe, but the shapes experimented in Korea are now quite limited. In this study, we considered built-up type of restraining member made up of precast reinforcement concrete and the steel core. we experimented the BRB according to AISC(2005) and evaluated seismic performances and hysteresis characteristics.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.7 no.2
• /
• pp.29-37
• /
• 2003

In this study, a story-wise distribution of hysteretic energy in steel moment resisting framse(MRF), buckling restrained braced frames(BRBF), and hinge-connected framed structures with buckling restrained braces(HBRBF) subjected to various earthquake ground excitations was investigated. Sixty earthquake ground motions recorded in different soil conditions were used to compute the energy demand in model structure. According to analysis results, the hysteretic energy in MRF and BRBF turned out to be the maximum at the base and monotonically diminishes with increasing height. However the story-wise distribution of hysteretic energy in HBRBF was relatively uniform over the height of the structure. In this case damage is not concentrated in a single story, and therefore it is considered to be more desirable than other systems. The story-wise energy distribution pattern under three different soil types turned out to be approximately the same.