• Structural Engineering and Mechanics
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• 제49권3호
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• pp.297-309
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• 2014

Under lateral loads Framed Tube (FT) system exhibits reduction of cantilever efficiency due to the effect of shear lag. Braced Tube (BT) represents a valuable solution to overcome shear lag problems by stiffening the exterior frame with diagonal braced members. This study investigates the effect of shear lag on BT and FT under wind load. Shear lag and top-level displacement results are compared with previous findings by researchers on FT and BT systems. The investigation of the effect of various configurations in BT on the reduction the shear lag is another objective of this study. The efficiency of each structure is evaluated using the linear response spectrum analysis to obtain shear lag. STADD Pro software is used to run the dynamic analysis of the models. Results show there is relatively less shear lag in all the BT configurations compared to the FT structural system. Moreover, the comparison of the obtained result with those derived by previous studies shows that shear lag is not proportional to lateral displacement. With respect to results, optimum BT configuration in term of lower shear lag caused by lateral loads is presented.

• Steel and Composite Structures
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• 제36권5호
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• pp.493-506
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• 2020

The load-slip relationship of the shear connection is an important parameter in design and analysis of composite structures. In this paper, a load-slip curve prediction method of the shear connection based on the artificial neural networks (ANNs) is proposed. The factors which are significantly related to the structural and deformation performance of the connection are selected, and the shear stiffness of shear connections and the transverse coordinate slip value of the load-slip curve are taken as the input parameters of the network. Load values corresponding to the slip values are used as the output parameter. A twolayer hidden layer network with 15 nodes and 10 nodes is designed. The test data of two different forms of shear connections, the stud shear connection and the perforated shear connection with flange heads, are collected from the previous literatures, and the data of six specimens are selected as the two prediction data sets, while the data of other specimens are used to train the neural networks. Two trained networks are used to predict the load-slip curves of their corresponding prediction data sets, and the ratio method is used to study the proximity between the prediction loads and the test loads. Results show that the load-slip curves predicted by the networks agree well with the test curves.

• Steel and Composite Structures
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• 제46권5호
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• pp.591-609
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• 2023

In some buildings, the lateral structural response of steel framed buildings depends on the shear walls and it is very important to study the behavior of these elements under near-field seismic loads. The link beam in the opening of the shear wall between two wall plates is investigated numerically in terms of behavior and effects on frames. Based on the length of the beam and its bending and shear behavior, three types of models are constructed and analyzed, and the behavior of the frames is also compared. The results show that by reducing the length of the link beam, the base shear forces reduce about 20%. The changes in the length of the link beam have different effects on the degree of coupling. Increasing the length of the link beam increases the base shear about 15%. Also, it has both, a positive and a negative effect on the degree of coupling. The increasing strength of the coupling steel shear wall is linearly related to the yield stress of the beam materials, length, and flexural stiffness of the beam. The use of a shorter link beam will increase the additional strength and consequently improving the behavior of the coupling steel shear wall by reducing the stresses in this element. The link beam with large moment of inertia will also increase about 25% the additional strength and as a result the coefficient of behavior of the shear wall.

• Structural Engineering and Mechanics
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• 제24권4호
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• pp.395-410
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• 2006

This paper reports the result of an investigation into wave propagation in orthotropic laminated piezoelectric cylindrical shells in hydrothermal environment. A dynamic model of laminated piezoelectric cylindrical shell is derived based on Cooper-Naghdi shell theory considering the effects of transverse shear and rotary inertia. The wave characteristics curves are obtained by solving an eigenvalue problem. The effects of layer numbers, thickness of piezoelectric layers, thermal loads and humid loads on the wave characteristics curves are discussed through numerical results. The solving method presented in the paper is validated by the solution of a classical elastic shell non-containing the effects of transverse shear and rotary inertia. The new features of the wave propagation in laminated piezoelectric cylindrical shells with various laminated material, layer numbers and thickness in hydrothermal environment and some meaningful and interesting results in this paper are helpful for the application and the design of the ultrasonic inspection techniques and structural health monitoring.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.565-568
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• 1999

The objective of this study is to investigate the hysteretic behaviors of exterior beam-column joints with high strength concrete (f'c≒1000kg/$\textrm{cm}^2$) subjected to cyclic loads. Four exterior subassemblages scaled down about 60% were tested, whose variables were with/without shear reinforcements and with/without slab and spandrel beams. Hoop bars and hooked steel fibers were used as the shear reinforcements. The test results showed that using hooked steel fiber reinforced concrete with volume ratio 1.5% at beam-column joints was very effective to resist shear stress due to cyclic loads.

• 한국구조물진단유지관리공학회 논문집
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• 제8권4호
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• pp.247-256
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• 2004

하층충격에 의한 2층 전단건물의 손상곡선을 엄계변위를 발생시키는 하중최대치 비와 임펄스 비를 이용하여 작성하였다. 손상곡선 작성에 필요한 구조물의 거동파악은 하중과 임펄스 응답행렬의 합성곱을 이용하여 구하였으며, 합성곱에 필요한 임펄스응답행렬은 모드중첩법을 이용하여 구하였다. 작성된 손상곡선으로부터 하층충격에 의한 각층의 안전성은 상층은 하중의 최대치에 그리고 하층은 임펄스의 크기에 민감한 것으로 파악되었다.

• 한국유체기계학회 논문집
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• 제19권6호
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• pp.14-18
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• 2016

Multi-MW wind turbines have very large blades over 40~50 m in length. Some factors like wind shear and tower shadow make an effect on asymmetric loads on the blades. Larger asymmetric loads are produced as the length of blade is getting longer. In this paper, a 2 MW on-shore wind turbine is considered and variations of thrust on 3 blades and rotor hub under wind shear are calculated by using a commercial Bladed S/W and dynamic properties of the thrust variations are investigated. It is shown that the amplitude of the asymmetric thrust on each blade under wind shear is getting larger as the wind speed increases, the frequency of the thrust variation on each blade is same as the one of rotor speed, and the frequency of the thrust variation at rotor hub is 3 times as high as the one of rotor speed.

• Computers and Concrete
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• 제20권5호
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• pp.521-527
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• 2017

This paper proposes using the multi-type sensor vibration measurements, such as from a relative displacement sensors and a traditional accelerometer for the damage detection of shear connectors in composite bridge under moving loads. Hilbert-Huang Transform (HHT) spectra of these responses will be fused with a data fusion approach i.e., Dempster-Shafer method, to detect the damage of shear connectors. Experimental studies on a composite bridge model in the laboratory are conducted to demonstrate the effectiveness and performance of using the proposed approach in detecting the damage of shear connectors in composite bridges. Both undamaged and damaged scenarios are considered. The detection results with the data fusion of multi-type sensor measurements show a more reliable and robust performance and accuracy, avoiding the false identifications.

• Steel and Composite Structures
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• 제21권6호
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• pp.1347-1368
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• 2016

In this article, an exact analytical solution for mechanical buckling analysis of symmetrically cross-ply laminated plates including curvature effects is presented. The equilibrium equations are derived according to the refined nth-order shear deformation theory. The present refined nth-order shear deformation theory is based on assumption that the in-plane and transverse displacements consist of bending and shear components, in which the bending components do not contribute toward shear forces and, likewise, the shear components do not contribute toward bending moments The most interesting feature of this theory is that it accounts for a parabolic variation of the transverse shear strains across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. Buckling of orthotropic laminates subjected to biaxial inplane is investigated. Using the Navier solution method, the differential equations have been solved analytically and the critical buckling loads presented in closed-form solutions. The sensitivity of critical buckling loads to the effects of curvature terms and other factors has been examined. The analysis is validated by comparing results with those in the literature.

• 한국지진공학회논문집
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• 제12권2호
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• pp.53-67
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• 2008

본 연구에서는 전단벽-모멘트골조 시스템으로서 전단벽이 주로 횡력을 부담하는 철근콘크리트 건물을 대상으로 다양한 설치형식과 마찰력의 총량 및 분포를 갖는 마찰형 감쇠기의 제진보강 효과를 수치해석을 통해 비교 분석하였다. 감쇠기의 설치형식으로서 전단벽에 인접한 대각가새형, 벽체가 없는 골조를 보강하는 대각가새형 및 벽체 단부를 보강하는 수직경계요소형을 고려하였다. 하중기준 강화로 설계용보다 크게 증가한 지진하중에 대해 건물의 재료비선형성을 고려한 비선형시간이력해석을 수행하여 에너지소산, 횡하중 및 부재손상도 측면에서 마찰형 감쇠기의 제진성능을 비교 분석하였다. 기준마찰력의 30% 수준의 총마찰력을 갖는 벽체보강 대각가새형 설치형식이 전반적으로 가장 우수한 제진성능을 보이며,이 경우에 마찰력 배분방식은 중요하지 않았다. 또한 일부층에 집중설치함으로써 전층설치에 약간 못미치는 제진성능을 얻을 수 있었다.