• Structural Engineering and Mechanics
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• 제50권6호
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• pp.741-754
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• 2014

The conventional PHC pile-footing connection is the weak part because the surface area and stiffness are sharply changed. The Composite PHC pile reinforced with the transverse shear reinforcing bars and infilled-concrete, hereafter ICP pile, has been developed for improving the flexural and shear performance. This paper investigates the cyclic behavior and performance of the ICP pile-footing connection. To investigate the behavior of the connection, one PHC and two ICP specimens were manufactured and then a series of cyclic loading tests were performed. From the test results, it was found that the ICP pile-footing connection exhibited higher cyclic behavior and connection performance compared to the conventional PHC pile-footing connection in terms of ductility ratio, stiffness degradation and energy dissipation capacity.

• 대한토목학회논문집
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• 제4권4호
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• pp.49-58
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• 1984

연약점토(軟弱粘土)(방콕)의 주기적(週期的) 반복하중(反復荷重)에 의(依)한 거동(擧動)을 구명(糾明)하기 위하여 부교란시료(不攪亂試料)에 대(對)한 일련(一連)의 반복하중(反復荷重)을 이용(利用)한 삼축압축시험(三軸壓縮試驗)을 시도(試圖)했다. 본(本)시험(試驗)은 포속압력(抱束壓力) 및 초기전단응력(初期剪斷應力)을 변화(變化)시켜 가면서 점토(粘土)의 전단변형(剪斷變形), 강도변화(强度變化) 등(等)을 조사(調査) 비교(比較)한다. 그 결과(結果) 초기전단응력(初期剪斷應力)이 증가(增加)함으로써 응력(應力)-변형곡선(變形曲線)은 적은 변화(變化)를 보였고, 반복하중(反復荷重)에 의(依)한 강도변화(强度變化)는 응력비(應力比)로 표현(表現)될 때 포속압력(抱束壓力)이 $1.0kgf/cm^2$이었을 때 더 컸으며, 축차응력(逐差應力)으로 표현(表現)될 경우(境遇)는 포속압력(抱束壓力)이 $1.5kgf/cm^2$이었을 때 크게 나타났다.

• Structural Engineering and Mechanics
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• 제78권4호
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• pp.413-423
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• 2021

Piers are the main lateral force-resisting members of high-speed railway (HSR) bridges used in China and are characterized by low axial load ratios, low longitudinal reinforcement ratios, low stirrup ratios, and high shear span ratios. It is well known that flexural, flexural-shear, and shear failures of piers may occur during an earthquake. In this study, a new shear strength model was developed to simulate the seismic failure of HSR solid piers accurately. First, low cyclic-loading test data of solid piers obtained in recent years were collected to set up a database for model verification. Second, based on the test database, the applicability of existing shear strength models was evaluated. Finally, a new shear strength model for HSR solid piers with round-ended cross-sections was derived based on the truss model and ultimate equilibrium theory. In comparison with existing models, it was demonstrated that the proposed model could be used to predict the shear strength of HSR piers more accurately.

• 한국지반공학회논문집
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• 제24권1호
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• pp.51-59
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• 2008

본 연구에서는 모래에서 점토에 이르는 넓은 범위의 혼합시료를 재성형하기 위하여 세립분으로 활성을 가지고 있는 자연점토와 조립분으로 규사를 혼합하여 실험에 이용하였다. 공시체는 세립분함유율이 낮은 범위 즉, 모래입자가 골격구조를 형성하고 있는 범위에 대해서는 다양한 간극비를 조성하기 위해 습윤 다짐방법을 이용하였으며, 활성을 나타내는 범위에 대해서는 정규압밀점토의 일정한 간극비를 조성하기 위해 예압밀방법을 이용하여 다양한 세립분함유율을 갖는 공시체를 제작하여 비배수 반복 전단실험을 수행하였다. 실험결과, 세립분함유율 20%미만의 시료에서 동일한 세립분함유율의 공시체에 대해 모래 골격간극비가 증가함에 따라 반복 전단강도는 감소하였으며 더욱이, 실험시료의 골격간극비가 규사의 최대간극비 이상의 범위에서는 흙의 구조가 다짐에너지의 영향을 거의 받지 않고 강도발현의 주체가 점토 매트릭스에 지배되는것을 알 수 있다. 모래점토 혼합토를 대상으로한 비배수 반복 전단실험에서 세립분 함유율이 20%미만의 낮은 영역에서 조립자의 구조는 반복 전단강도 특성에 큰 영향을 미치며 더욱이, 세립분함유율보다 모래구조의 밀도에 유의하는것이 더욱 적합한 것을 알 수 있다.

• 한국지진공학회논문집
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• 제20권4호
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• pp.211-222
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• 2016

Reinforced concrete shear walls with deficient reinforcement details are tested under cyclic loading. The deficiency of reinforcement details includes insufficient splice length in U-stirrups at the ends of horizontal reinforcement and boundary column dowel bars found in existing low- to mid-rise Korean buildings designed non-seismically. Three test specimens have rectangular, babel and flanged sections, respectively. Flexure- and shear-controlled models for reinforced concrete shear walls specified in ASCE/SEI 41-13 are compared with the flexural and shear components of force-displacement relation extracted separately from the top displacement of the specimen based on the displacement data measured at diverse locations. Modification of the shear wall models in ASCE/SEI 41-13 is proposed in order to account for the effect of bar slip, cracking loads in flexure and shear. The proposed modification shows better approximation of the test results compared to the original models.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.1422-1430
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• 2008

Cyclic simple shear test apparatus was used to investigate the dynamic response of liquefiable soils as reclamation material. The specimen were reclamation using simple air-pluviation method. The confining stress was applied the range of 100 kpa to 200 kpa. The resulted strain was in the range of $10^{-3}$ ~ 5 %. Based on these test results modulus reduction curve, damping curve and cyclic strength curve were developed. The developed curves were compared to those already available in literature. The obtained curves can be applied to FEM or equivalent linear analysis such as SHAKE for ground response analysis.

• Earthquakes and Structures
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• 제9권3호
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• pp.541-562
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• 2015

This paper aims at developing the knowledge on the seismic behavior of dowel beam-to-column connections, typically employed in precast buildings in Europe. Despite the large diffusion of the industrial buildings, a high seismic vulnerability was exhibited by these structures, mostly due to the connection systems deficiencies, during some recent earthquakes (Emilia 2012, Turkey 2011). An experimental campaign was conducted on a typical dowel connection between an external column and a roof beam. In this paper, the performed cyclic shear test is described. According to the experimental results, the seismic response of the system is evaluated in terms of strength, stiffness and failure mechanism. Moreover, the complete damage pattern of the test is described by means of the instrumentations records. The connection failure occurred due to the concrete cover failure in the column (splitting failure). Such a mechanism corresponds to a negligible energy dissipation capacity of the connection, compared to the overall seismic response of the structure. The experimental results are also compared with the results of a similar monotonic shear test, as well as with some literature relationships for predicting the strength of dowel connections under horizontal (seismic) loads.

• 대한기계학회논문집A
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• 제31권2호
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• pp.166-173
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• 2007

Fatigue fracture behavior of a hybrid bolted joint was evaluated in comparison to the case of static fracture. Two kinds of specimens were fabricated for the mechanical tests; a hybrid bolted joint specimen for the shear test and a hybrid joint part specimen applied in the real tilting car body for the bending test. Characteristic fracture behaviors of those specimens under cyclic toads were obviously different from the case under static loads. For the hybrid bolted joint specimen, static shear loading caused the fracture of the bolt body itself in a pure shear mode, whereas cyclic shear loading brought about the fracture at the site of local tensile stress concentration. For the hybrid joint part specimen, static bend loading caused the shear deformation and fracture in the honeycomb core region, while cyclic bend loading did the delamination along the interface between composite skin and honeycomb core layers as well as the fracture of welded joint part. Experimental results obtained by static and fatigue tests were reflected in modifications of design parameters of the hybrid joint structure in the real tilting car body.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 가을 학술발표회 논문집
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• pp.243-249
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• 1993

The porpose of this study is to suggest an experimental for shear wall of reinforced concrete wall structure. A series of experimental be performed for earned to strength and deformation property of reinforced concrete shear wall. These specimens are three R/C walls among five models which had boundary. As a result, it was found that cyclic experiment is very proper and cyclic time must be increased 3 or 5 times. Monotonic test results was indicated over 15% than other experiment for yielding strength and ultimate strength.

• 한국지반공학회논문집
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• 제36권9호
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• pp.21-32
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• 2020

본 연구에서는 포항 액상화 현상 발생 현장에서 채취한 모래를 사용하여 진동삼축시험 및 전단파 속도 측정을 수행하였으며, 시험결과를 기반으로 액상화 저항곡선을 도출하여 액상화 저항강도(CRR)를 산정하였다. 전단파 속도는 지진 발생 전 현장상태를 모사하고자 압밀 단계 종료 시점에서 측정한 값을 활용하였다. 시험을 통해 액상화 저항강도에 대한 두 가지 인자(입도분포, 상대밀도)의 영향을 확인하였으며 기존 문헌에서 제시된 타 사질토의 액상화 저항강도와의 비교를 통해 포항 모래의 액상화 저항강도를 정량적으로 평가하였다. 또한, 측정한 전단파 속도를 활용하여 실제 현장에서 사용되는 액상화 평가 곡선과의 비교를 통해 시험 결과의 신뢰성을 확인하였다.