• 한국지진공학회논문집
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• 제23권2호
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• pp.119-129
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• 2019

Many reinforced concrete (RC) buildings constructed prior to 1980's lack important features guaranteeing ductile response under earthquake excitation. Structural components in such buildings, especially columns, do not satisfy the reinforcement details demanded by current seismic design codes. Columns with deficient reinforcement details may suffer significant damage when subjected to cyclic lateral loads. They can also experience rapid lateral strength degradation induced by shear failure. The objective of this study is to accurately simulate the load-deformation response of RC columns experiencing shear failure. In order to do so, model parameters are calibrated to the load-deformation response of 40 RC column specimens failed in shear. Multivariate stepwise regression analyses are conducted to develop the relationship between the model parameters and physical parameters of RC column specimens. It is shown that the proposed predictive equations successfully estimated the model parameters of RC column specimens with great accuracy. The proposed equations also showed better accuracy than the existing ones.

• Current Optics and Photonics
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• 제7권4호
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• pp.337-344
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• 2023

Three-point bending is the main method for measuring the elastic modulus of a thin plate. Although various displacement transducers may be used to measure the bending, these are single-point measurements, and it is difficult to eliminate the error caused by eccentric load and shear force. Error-correction models for the elastic modulus of quartz glass using digital speckle interferometry are proposed for eccentric load and shear force. First, the positional misalignment between maximum deflection and load is analyzed, and the error caused by eccentric load is corrected. Then, the additional displacement caused by shear force at different positions of the quartz glass plate is explored. The effect of shear deformation is also corrected, by measuring two points. Since digital speckle interferometry has the advantage of full-field measurement, it can simultaneously obtain deflection data for multiple points to realize error correction. Experimental results are presented to demonstrate that the proposed model can effectively correct the measurement error of the elastic modulus.

• 대한토목학회논문집
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• 제28권2A호
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• pp.269-279
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• 2008

본 논문에서는 전편논문에서 제안한 부정정 스트럿-타이 모델 및 하중분배율 결정식을 ACI 318-05 스트럿-타이 모델 설계기준에 적용하여 파괴실험이 수행된 229개 단순지지 철근콘크리트 깊은 보의 극한강도를 평가하였다. 또한 229개 깊은 보의 극한강도를 실험식, 실험 전단강도모델에 기초한 설계기준, 이론 전단강도모델에 기초한 설계기준, 그리고 현 스트럿-타이 모델 설계기준 등으로 평가하고, 그 결과를 본 연구의 방법에 의한 결과와 비교분석하여 본 연구에서 제안한 방법의 적합성을 검증하였다.

• 콘크리트학회지
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• 제10권6호
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• pp.161-168
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• 1998

본 연구는 수직전단하중에 대한 프리캐스트 바닥판간 이음부거동을 규명하고 수직전단력 전달에 유리한 이음부 구조도출을 위해 female-female 형식의 이음부를 제안하고, 실험 및 유한요소해석을 수행한 것이다. 경사각, 이음부깊이/높이 및 구속응력을 변수로 총 18개의 실험체에 대한 실험 및 유한요소해석결과 ,이음부의균열저항성 개선을 위해서는 경사각이 60。, D/H가 1/4일 경우가 유리하며 측방향구속으로 이음부를 압축상태로 유지하는 것이 이음부 균열방지에 효과적임을 알았다.

• 한국해안해양공학회지
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• 제7권3호
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• pp.257-264
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• 1995

파와 해류가 동시에 작용할 때 소류사 이동에 미치는 제 요인을 파악하고, 합성류 소류사량 산정을 위하여 이들 제 요인 중 평균마찰력과 최대마찰력을 모두 고려하기 위하여 하천 소류사량 산정식들 중 적절한 형식 몇가지를 선택하였다. 합성류에 의한 최대마찰력과 평균마찰력의 산정을 위하여 BYO 모형을 적용하였으며, 일방향흐름 마찰계수 산정식은 수정 Keulegan식을 사용하였고 등가조고는 일방향흐름 관측결과와 일치하는 마찰력이 산정되는 수치를 택하였다. 각 소류사량 산정식에 도입된 비례상수는 Bijker(1966)의 수조관측자료에 적용하여 결정하였으며, 최종 결과로부터 각 산정식을 비교하여 논하였다.

• 한국전산구조공학회논문집
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• 제22권1호
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• pp.105-115
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• 2009

휨거동을 하는 전단벽을 대상으로 동일한 총 단면적을 갖는 1개의 전단벽과 마찰형 감쇠기로 연결된 전단벽의 내진성능을 수치해석을 통해 비교하였다. KBC 2005 설계스펙트럼을 근거로 축소 조절한 7개의 지진파를 입력하중으로 마찰형 감쇠기가 설치된 전단벽의 평균응답을 분석하였다. 마찰형 감쇠기의 중요한 설계변수인 기준 마찰력인 슬립하중은 각층의 마찰형 감쇠기 위치에 생기는 수직방향 전단력의 총합의 5, 10, 20, 30, 60, 90%값으로 하여 슬립이 특정한 층에 편중되지 않도록 하였다. SeismoSturct 프로그램을 이용해 비선형시간이력 해석을 수행하여 밑면 전단력, 에너지 소산량, 1층 벽체곡률, 최상층변위 측면에서 마찰 감쇠기의 제진성능을 분석하였다. 기준마찰력의 30%이하 수준의 총 마찰력을 갖는 마찰 감쇠기가 우수한 제진성능을 보였다.

• International Journal of Concrete Structures and Materials
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• 제6권2호
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• pp.65-78
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• 2012

An experimental study was carried out to evaluate fresh properties of a moderately high-strength (high-flowing) self-compacting concrete (SCC) and to investigate shear behavior and performance of deep beams made with SCC. Fresh and hardened properties of normal concrete (NC) and SCC were evaluated. The workability and compacting ability were observed based on casting time and number of surface cavities, respectively. Four-point loading tests on four deep beams (two made with SCC and two with NC) were then conducted to investigate their shear behavior and performance. Shear behavior and performance of beams having two different web reinforcements in shear were systematically investigated in terms of crack pattern, failure mode, and load-deflection response. It was found from the tests that the SCC specimen having a normal shear reinforcement condition exhibited a slightly higher load carrying capacity than the corresponding NC specimen, while the SCC specimen having congested shear reinforcement condition showed a similar load carrying capacity to the corresponding NC specimen. In addition, a comparative study between the present experimental results and theoretical results in accordance with ACI 318 (Building Code Requirements for Reinforced Concrete (ACI 318-89) and Commentary-ACI 318R-89, 1999), Hsu-Mau's explicit method (Hsu, Cem Concr Compos 20:419-435, 1998; Mau and Hsu, Struct J Am Concr Inst 86:516-523, 1989) and strut-and-tie model suggested by Uribe and Alcocer (2002) based on ACI 318 Appendix A (2008) was carried out to assess the applicability of the aforementioned methods to predict the shear strength of SCC specimens.

• 한국항공우주학회지
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• 제35권12호
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• pp.1129-1134
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• 2007

페이로드 페어링은 외부환경으로부터 위성 및 전자 탑재물들을 보호한다. 그리고 위성 분리 전에 페이로드 페어링은 투하 된다. 페어링 분리를 위하여 전단볼트로 체결된 체결프레임이 페이로드 페어링에 조립되어 있다. 전단볼트의 역할은 전체 구조하중을 견디며, 화약폭발력에 의해 절단이 된다. 그리고 전단볼트가 절단된 후 전단볼트로 연결되었던 체결 프레임은 분리된다. 본 논문에서는 전단볼트 설계에 대한 구조시험과 해석을 수행하였다. 구조시험은 체결 프레임을 포함한 하드웨어에 압축, 굽힘, 전단하중을 부가하였다. 시험결과 전단볼트는 비행하중 지지를 위한 구조강도와 화약폭발에 의해 절단되는데 요구되는 낮은 강도 조건을 만족하였다.

• Computational Structural Engineering : An International Journal
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• 제1권2호
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• pp.117-130
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• 2001

Investigations of low-rice unbounded reinforced concrete shear walls with or without openings are performed with comparison of analytical and experimental results. Theoretical analysis is based on nonlinear finite element algorithm, which incorporates concrete failure criterion and nonlinear constitutive relationships. Studios focus on the effects of height-to-length ratio of shear walls, opening ratio, horizontal and vertical reinforcement radios, and diagonal reinforcement. Analytical solutions conform well with experimental results. Equations for cracking, yielding and ultimate loads with corresponding lateral displacements are derived by regression using analytical results and experimental data. Also, failure modes of low-rise unbounded shear walls are theoretically investigated. An explanation of change in failure mode is ascertained by comparing analytical results and ACI code equations. Shear-flexural failure can be obtained with additional flexural reinforcement to increase a wall's capacity. This concept leads to a design method of reducing flexural reinforcement in low-rise bounded solid shear wall's. Avoidance of shear failure as well as less reinforcement congestion leer these walls is expected.

• Steel and Composite Structures
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• 제24권1호
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• pp.1-13
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• 2017

In order to improve the deformation capacity of the high-strength concrete shear wall, five high-strength concrete shear wall specimens confined with high-strength rectangular spiral reinforcement (HRSR) possessing different parameters, were designed in this paper. One specimen was only adopted high-strength rectangular spiral hoops in embedded columns, the rest of the four specimens were used high-strength rectangular spiral hoops in embedded columns, and high-strength spiral horizontal distribution reinforcement were used in the wall body. Pseudo-static test were carried out on high-strength concrete shear wall specimens confined with HRSR, to study the influence of the factors of longitudinal reinforcement ratio, hoop reinforcement form and the spiral stirrups outer the wall on the failure modes, failure mechanism, ductility, hysteresis characteristics, stiffness degradation and energy dissipation capacity of the shear wall. Results showed that using HRSR as hoops and transverse reinforcements could restrain concrete, slow load carrying capacity degeneration, improve the load carrying capacity and ductility of shear walls; under the vertical force, seismic performance of the RC shear wall with high axial compression ratio can be significantly improved through plastic hinge area or the whole body of the shear wall equipped with outer HRSR.