• Structural Engineering and Mechanics
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• 제32권4호
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• pp.531-547
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• 2009

This paper presents the experimental results on the strength behavior and failure modes of box beam-to-circular column connections in steel piers. Previous research introduced parameters such as joint central angles, extension of horizontal stiffeners, and use of equivalent web depth, which ignored strength behavior and failure modes of box beam-to-circular column connections. The use of equivalent web depth $d_2$ is not reasonable when central angle ${\alpha}$ is closer to $90^{\circ}$; therefore, a monotonic loading test has been performed for eight connection specimens. From the test, it is identified that the connection with the circular column is stronger than the connection with the box-sectioned substitution column. Also, the strength of the beam-to-column connections with horizontal stiffeners is higher than the one of the no column stiffeners. The concrete-filled effect of box beam-to-circular column connection is also investigated, and the experimental yield strength of the connection is compared with the theoretical one. Also, more a reasonable equivalent web depth is suggested. The failure modes of connection are clearly defined.

• 한국강구조학회 논문집
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• 제14권3호
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• pp.433-441
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• 2002

본 연구에서는 원형기둥과 상자형보로 이루어진 접합부의 응력분포에 관하여 검토하였다. 접합각도를 변수로 하는 총 12개의 비충전 및 충전 원형기둥-상자형보 접합부에 대한 실험을 수행하였다. 접합부의 수직 및 전단응력 분포특성을 파악하기 위해 우선 기존 설계식에서 주로 사용하고 있는 환산깊이 dc'및 추가적의 환산깊이를 도입하여 검토하였고 이를 적용하여 계산한 응력값을 실험값과 비교.검토하였다. 그 결과 비충전 및 충전접합부의 수직 및 전단응력 실험값은 설계식에 의한 값과 많은 차이점을 나타냄을 알 수 있었고, 환산깊이 dc'은 접합각도가 커질수록 급격히 감소하여 설게식에 적용하기에는 한계가 있음을 확인하였다. 또한 충전 접합부가 비충전 접합부에 비해 작은 응력값을 나타냈으며 충전접합부의 실험값을 비충전 접합부의 응력산정 방법을 준용하는 현행 설계식의 값과 비교. 분석하였다.

• 대한조선학회지
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• 제17권2호
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• pp.11-16
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• 1980

For vibration analysis of stiffened plates the orthotropic plate analogy is commonly accepted. As to stiffened plates in contact with water, however, there is still much uncertainty in estimation of the added mass because of the lack of direct methods. The authors, considering that for added mass of plates there are many reliable data derived theoretically or experimentally available, suggest a method to estimate the added mass of a stiffened plate by combining the mass increase factor, $\beta$, of an equivalent orthotropic plate and the correction factor, $\kappa$, for the effects of stiffeners. The latter is to be derived from systematic experimental investigations. Then, the natural frequency in water, f', can be calculated from that in air, f, by the equation $f'=f/\sqrt{1+\kappa\beta}$. To investigate practical applicability of this method, a systematic experiment was carried out with five uniaxially stiffened plates. Each of them had a plate of same size, $600mm{\times}600mm{\times}3.2mm$, but stiffeners of different size in the web-depth, 41.6mm, 51.2mm or 66.8mm and of different spacing 75mm, 100mm, or 150mm. Natural frequencies were measured under simply supported-edge conditions in both air and water, and corresponding $\kappa$ values derived. In spite of wide variations of web-depth and spcae of stiffeners, the experimental results show that the diversity of $\kappa$ values is not remarkable; mean values of $\kappa$ are 1.31 with standard deviation of 0.025 for the first modes and 1.27 with that 0.077 for the second modes. Hence, the authors concluded that the above $\kappa$ values can be used generally for the cases of uniaxially stiffened plates both sides of which contact with water, and that $\kappa$ values of general use for the cases of cross-stiffened plates may also be obtainable from similar experiments.

• Structural Engineering and Mechanics
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• 제84권3호
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• pp.295-310
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• 2022

This paper proposes a modified bar simulation method for analyzing the shear lag effect of variable sectional box girder with multiple cells. This theoretical method formulates the equivalent area of stiffening bars and the allocation proportion of shear flows in webs, and re-derives the governing differential equations of bar simulation method. The feasibility of the proposed method is verified by the model test and finite element (FE) analysis of a simply supported multi-cell box girder with constant depth. Subsequently, parametric analysis is conducted to explore the mechanism of shear lag effect of varied sectional cantilever box girder with multiple cells. Results show that the shear lag behavior of variable box-section cantilever box girder is weaker than that of box girder with constant section. It is recommended to make the gradient of shear flow in the web with respect to span length vary as smoothly as possible for eliminating the shear lag effect of box girder. An effective countermeasure for diminishing shear lag effect is to increase the number of box chambers or change the variation manner of bridge depth. The shear lag effect of varied sectional cantilever box girder will get more server when the length of central flanges is shorter than 0.26 or longer than 0.36 times of total width of top flange, as well as the cantilever length exceeds 0.29 times of total length of box's flange. Therefore, the distance between central webs can adjust the shear lag effect of box girder. Especially, the width ratio of cantilever plate with respect to total length of top flange is proposed to be no more 1/3.

• 콘크리트학회논문집
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• 제27권6호
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• pp.615-623
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• 2015

철근콘크리트 전단벽의 전단강도를 예측하기 위한 기존 연구자들의 스트럿-타이 모델(STM)들은 횡하중 및 상부의 축력에 대한 전단벽의 내부 힘의 흐름과 웨브의 전단철근에 의해 전달되는 전단력의 비율을 명확히 제시하고 있지 않다. 이를 개선하기 위해서, 이 연구에서는 콘크리트 파괴역학의 균열 띠 이론을 기반한 단순한 STM을 개발하였다. 응력이완 스트립을 동반하는 콘크리트 스트럿의 등가유효너비는 중립축 깊이와 콘크리트 유효압축강도 계수로 결정되었다. 균열 띠 확장영역의 전단 전달 메커니즘은 강성법에 의한 트러스 작용으로부터 산정되었다. 웨브 콘크리트 스트럿과 전단철근에 의한 전단 전달력은 응력이완 스트립과 균열 띠 이론을 기반한 에너지평형조건으로부터 유도되었다. 제시된 모델은 Siao와 Hwang et al.의 STM에 비해 150여개의 기존 실험결과의 경향을 잘 예측하였다. 또한, 제시된 STM은 각 변수에 따른 무차원된 전단강도의 경향을 잘 반영하고 있다.