• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1987년도 학술발표회 발표강연집
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• pp.51-80
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• 1987

In this studys a numerical analysis on the defomation of foundation layer was carried out by indroducing joint element. The method using the joust element between adj assent different materials has been originally developed for rock behavior(Goodman, et al. 1968) . The application of this method to the interface between the footing and soil layer proved satisfactory(Ghaboussi p et at. 1973). Authors tried to obtain the deformation of rrcompound foundation layerg", which vertically or horizontally or both consists of the natural(or intact) soft clay layer and the layer improved artificially in order to get high stiff-fness with replacement or chemical treatment to reduce the excessively detrimental settlemellt or lateral displacement in case of banking or building the civil structure on the soft layer. The joint conditions were classified into three categories : contacts sliding and separation. By coupling "JOINT" as a subroutine into multi-purpose code for the finite element method of the foundatlion daveloped by authors on the assumption that shearing and normal displacement can not be coupledl which terms pinon-dilatant" and by selecting modified Cam-clay modeIP the deformation analysis was performmed. The results using joint element were compared with those secured without introduction of joint element Nain results analized are as follows : 1. For the prediction of settlement and lateral desplacement, the result due to joint element was evaluated larger, which was regarded safe. 2. For the determination of ultimate bearing capacetyi the value using joint element appeared smaller by 20%, which was also safe.

• 한국전산구조공학회논문집
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• 제15권1호
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• pp.9-20
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• 2002

본 연구의 목적은 비선형 흙-구조물 상호 작용문제를 연구하기 위한 계산 절차를 개발하는 것이다. 흙-구조물 상호 작용 거동을 연구하기 위하여 연직과 수평하중을 동시에 받은 대상기초와 강널말뚝으로 보강된 기초지반에 대한 유한 요소 수치해석을 하였으며 흙과 기초구조물 사이의 상호작용 거동을 모델하기 위하여 접합요소를 사용하였다 주 해석 결과는 다음과 같다. 1. 침하와 측방변위의 예측에 대해서는, 접합요소를 사용한 결과가 더 큰 값을 얻었다. 2. 극한지지력 결정에 대해서는 접합요소를 사용한 경우가 약 12%정도 더 작게 나타났다 3. 대상기초의 수평과 연직변위는 접합요소의 영향을 받았다.

• Earthquakes and Structures
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• 제18권1호
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• pp.15-25
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• 2020

The seismic behaviour of reinforced concrete (RC) columns made from high-strength materials was investigated experimentally. Six high-strength concrete specimen columns (1:4 scale), which included three with high-strength stirrups (HSSs) and three with normal-strength stirrups (NSSs), were tested under a combination of high axial and reversed cyclic loads. The effects of stirrup strength and the ratio of transverse reinforcement on the cracking patterns, hysteretic response, strength, stiffness, ductility, energy dissipation and strain of transverse reinforcement were studied. The results indicate that good seismic behaviour of an RC column subjected to high axial compression can be obtained by using a well-shaped stirrup. Stirrup strength had little effect on the lateral bearing capacity. However, the ductility was significantly modified by improving the stirrup strength. When loaded with a large lateral displacement, the strength reduction of NSS specimens was more severe than that of those with HSSs, and increasing the stirrup strength had little effect on the stiffness reduction. The ductility and energy dissipation of specimens with HSSs were superior to those with NSSs. When the ultimate displacement was reached, the core concrete could be effectively restrained by HSSs.

• Structural Engineering and Mechanics
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• 제66권3호
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• pp.399-409
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• 2018

This paper demonstrates the potential application of machine learning algorithms for approximate prediction of the load and deflection capacities of the novel type of Laced Steel Concrete-Composite (LSCC) beams proposed by Anandavalli et al. (Engineering Structures 2012). Initially, global and local responses measured on LSCC beam specimen in an experiment are used to validate nonlinear FE model of the LSCC beams. The data for the machine learning algorithms is then generated using validated FE model for a range of values of the identified sensitive parameters. The performance of four well-known machine learning algorithms, viz., Support Vector Regression (SVR), Minimax Probability Machine Regression (MPMR), Relevance Vector Machine (RVM) and Multigene Genetic Programing (MGGP) for the approximate estimation of the load and deflection capacities are compared in terms of well-defined error indices. Through relative comparison of the estimated values, it is demonstrated that the algorithms explored in the present study provide a good alternative to expensive experimental testing and sophisticated numerical simulation of the response of LSCC beams. The load carrying and displacement capacity of the LSCC was predicted well by MGGP and MPMR, respectively.

• Structural Engineering and Mechanics
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• 제61권1호
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• pp.1-13
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• 2017

The effectiveness of the repair scheme for the damaged captive-columns with CFRPs (Carbon Fiber Reinforced Polymer) was investigated in terms of response quantities such as strength, ductility, dissipated energy and stiffness degradation. Two 1/3 scale, one-story one-bay RC (Reinforced Concrete) frames were designed to represent the substandard RC buildings in Turkish building stock. The first one, which is the reference specimen, is the bare frame without infill wall. Partial infill wall with opening was constructed between the columns of the second frame and this caused captive column defect. Severe damage was observed with the concentration of shear cracks in the second specimen columns. Then, the damaged members were repaired by CFRP wrapping and retested. For the three test series, similar reversed cyclic lateral displacement under combined effect of axial load was applied to the top of the columns. Overall response of the bare frame was dominated by flexural cracks. Brittle type of shear failure in the column top ends was observed in the specimen with partial infill wall. It was observed that former capacity of damaged members of the second frame was recovered by the applied repair scheme. Moreover, ultimate displacement capacity of the damaged frame was improved considerably by CFRP wrapping.

• Steel and Composite Structures
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• 제24권4호
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• pp.409-423
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• 2017

This paper presents an experimental study on damage evolution laws of solid-web steel reinforced concrete (SRC) T-shaped columns along the direction of the web under various loadings. Ten specimens with a scale ratio of 1/2 and a shear span ratio of 2.5 were designed and fabricated. The influences of various parameters, including the axial compression ratio, steel ratio, and loading mode, were examined. The mechanical performances including load-displacement curve and energy dissipation capacity under the monotonic and low cyclic loadings were analyzed. Compared with the monotonic loading, bearing capacity, ultimate deformation capacity, and energy dissipation capacity of the specimens decrease to some extent with the increase of the displacement amplitude and the number of loading cycle. The results show that the damage process of the SRC T-shaped column can be divided into five stages, namely non-damage, slight-damage, steadily-developing-damage, severe-damage and complete-damage. Finally, based on the Park-Ang model, a modified nonlinear damage model which combines the maximum deformation with hysteretic energy dissipation is proposed by taking into account the dynamic influence of the aforementioned parameters. The results show that the modified model in this paper is more accurate than Park-Ang model and can better describe the damage evolution of SRC T-shaped columns.

• Structural Engineering and Mechanics
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• 제74권1호
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• pp.69-82
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• 2020

A significant defect of space structures is the progressive collapse issue which may restrict their applicability. Force limiting devices (FLDs) have been designed to overcome this deficiency, though they don't operate efficiently in controlling the force displacement characteristics. To overcome this flaw, a new type of FLD is introduced in the present study. The "all steel accordion force limiting device" (AFLD) which consists of three main parts including cylindrical accordion solid core, tubular encasing and joint system is constructed and its behavior has been studied experimentally. To improve AFLD's behavior, Finite element analysis has been carried out by developing models in ABAQUS software. A comprehensive parametric study is done by considering the effective design parameters such as core material, accordion wave length and accordion inner diameter. From the results, it is found that AFLD can obtain a perfect control on the force-displacement characteristics as well as attaining the elastic-perfect plastic behavior. Obtaining higher levels of ultimate load carrying capacity, dissipated energy and ductility ratio can be encountered as the main privileges of this device. Ease of construction and erection are found to be further advantages of AFLD. Based on the obtained results, a procedure for predicting AFLD's behavior is offered.

• Journal of the Korean Wood Science and Technology
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• 제30권3호
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• pp.97-103
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• 2002

This study was carried out to obtain basic information on racking resistance of shear walls and the factors affecting racking resistance of shear walls. Shear walls constructed by larch lumber nominal 50 mm × 100 mm framing and various sheathing materials were tested by applying monotonic and cyclic load functions. Shear walls with various stud spacing such as 305 mm, 406 mm, and 610 mm were tested under both of monotonic and cyclic loads and shear walls with various aspect (height-width) ratios were tested under cyclic load functions. The effect of hold-down connectors in shear walls was also tested under cyclic load functions. Racking resistance of shear walls has very close linear relation with stud spacing and width of shear walls. The ultimate racking strength of shear walls was reached at around or before the displacement of 20 mm. It was proposed in this study that the minimum racking strength and minimum width for shear wall be 500 kgf and 900 mm, respectively. Load-displacement curves obtained by racking tests under monotonic load functions can be represented by three straight line segments. Under cyclic load functions, envelope curves can be divided into three sections that can be represented by straight lines and the third section showed almost constant or decreasing slope.

• 콘크리트학회논문집
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• 제26권6호
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• pp.687-694
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• 2014

이 연구에서는 철근콘크리트 전단벽의 경계요소의 연성설계를 위한 변위연성비모델을 제시하였다. 부재의 길이에 따른 곡률과 자유단에서의 변위를 산정하기 위한 전단벽의 단면의 변형률 및 내부힘들의 분포는 베르누이(Bernoulli)의 정리, 변형률 적합조건 및 힘의 평형조건을 이용하여 이상화하였다. 경계요소내의 횡보강근에 의한 구속효과는 Razvi and Saatcioglu에 의해 제시된 콘크리트의 응력-변형률 관계를 이용하여 고려하였다. 항복시 및 최대내력 이후 최대모멘트 80%에서의 곡률은 등가소성 힌지길이 개념을 도입하여 변위값으로 환산하였다. 일반화된 변위연성비의 모델은 다양한 범위에서 수행된 변수연구로부터 얻어진 데이터들의 회귀분석을 통하여 단순식으로 정립되었다. 제시된 단순모델은 실험결과 대비 평균, 표준편차 및 변동계수가 각각 1.05, 0.19 및 0.18로 대부분의 실험결과의 경향을 잘 예측하였다. 따라서 제시된 모델은 경계요소에서 소요연성비에 따른 횡보강근의 상세를 결정하는데 쉽게 이용될 수 있을 것으로 기대된다.

• 지질공학
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• 제3권2호
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• pp.177-190
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• 1993

연약지반에서 성토나 교대등에 의한 편재하중이 작용하게 되면 지반중에는 침하, 측방변위, 융기 및 전단파괴 등의 큰 소성적인 전단변형이 발생하여 지반 및 구조물에 큰 피해를 주는 것을 많이 볼 수 있다. 본 연구는 이러한 연약지반에서 편재하중에 의한 지반의 제반변형에 대한 거동을 연구하기 위하여 기존의 이론적인 배경을 조사하고 모형실험을 통한 실측치를 이용하여 서로 비교분석하여 보았다. 모형실험은 먼저 모형재하장치를 제작하고 토조안에 연약한 흙시료를 채워 비배수상태에서 일정한 시간간격으로 하중단계를 증가시켜 가면서 변형의 상태를 관측하였다. 실험결과를 토대로 지반특성과 변위량의 관계, 한계하중 및 극한지지력, 지반의 소성유동의 상태 및 측방 유동압의 검토 등을 상세하게 분석하여 기존의 이론과 비교해 봄으로써 실제 연약지반상에서의 측방변형에 대한 원인을 규명함으로써 그로 인한 피해를 사전에 방지하고자 한다.