• Title/Summary/Keyword: half beam

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Behaviour of RC beam-column joint with varying location of construction joints in the column

  • Vanlalruata, Jonathan;Marthong, Comingstarful
    • Earthquakes and Structures
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    • v.20 no.1
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    • pp.29-38
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    • 2021
  • According to ACI 224.3R-95 (ACI, 2013), construction joints (cold joint) in the column are to be provided at the top of floor slab for column continuing to the next floor and underside of floor slab and beam. A recent study reveals that providing cold joint of the mentioned location significantly reduced the seismic performance of the frame structures. Since, the construction joints in multi-story frame structures normally provided at the top of the floor slabs and at soffit of the beam in the column. This study investigated the effect of construction joint at various location in the column of beam-column joint such as at the top of floor slab, soffit level of the beam, half the depth of beam below the soffit of the beam and at a full depth of the beam below the soffit of the beam. The study revealed that there is an improvement in seismic capacity of the specimens as the location of cold joint is placed away from the soffit of the beam for lower story column.

Analysis of Axially Displaced Ellipse Gregorian Dual Reflector Antennas (축이동 그레고리안 이중 반사경 안테나의 해석)

  • 임성빈;최경국;최학근
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.11
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    • pp.1161-1169
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    • 2003
  • In this paper, ADE(Axially Displaced Ellipse) Gregorian dual reflector antennas, which are the special form of Gregorian dual reflector antennas, were analyzed. In the procedure of antenna analysis, the aperture field distribution was obtained by using the geometrical optics and their far-field radiation characteristics were analyzed by using the aperture field method. The analysis results such as antenna efficiency, HPBW(Half Power Beam Width), FNBW(First Null Beam Width), and FSL(First Sidelobe Level) were presented as functions of edge taper and size of main reflector and subreflector. From the results in this paper, we could confirm that ADE reflector antennas have the different radiation characteristics from the classical dual reflector antennas.

Quadratic B-spline finite element method for a rotating non-uniform Rayleigh beam

  • Panchore, Vijay;Ganguli, Ranjan
    • Structural Engineering and Mechanics
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    • v.61 no.6
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    • pp.765-773
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    • 2017
  • The quadratic B-spline finite element method yields mass and stiffness matrices which are half the size of matrices obtained by the conventional finite element method. We solve the free vibration problem of a rotating Rayleigh beam using the quadratic B-spline finite element method. Rayleigh beam theory includes the rotary inertia effects in addition to the Euler-Bernoulli theory assumptions and presents a good mathematical model for rotating beams. Galerkin's approach is used to obtain the weak form which yields a system of symmetric matrices. Results obtained for the natural frequencies at different rotating speeds show an accurate match with the published results. A comparison with Euler-Bernoulli beam is done to decipher the variations in higher modes of the Rayleigh beam due to the slenderness ratio. The results are obtained for different values of non-uniform parameter ($\bar{n}$).

Beam focusing by a single subwavelength metal slit surrounded by chirped dielectric surface gratings (금속 슬릿 주변에 유전체 chirped grating을 배열함으로써 구현한 beam focusing)

  • Kim, Se-Yun;Park, Jeong-Hyeon;Im, Yong-Jun;Kim, Hwi;Lee, Byeong-Ho
    • Proceedings of the Optical Society of Korea Conference
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    • 2007.07a
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    • pp.255-256
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    • 2007
  • We propose a novel method for the beam focusing by a single subwavelength metal slit surrounded by chirped dielectric surface gratings. In the proposed method, the period of each grating is chirped to make a focused beam at the desired position. Design of the grating structures for optimal beam focusing and the analysis of the field distribution are conducted based on the rigorous coupled wave analysis (RCWA). It is shown that the focused beam is formed at 1.5${\mu}m$ from the metal substrate and its full width at half maximum (FWHM) is 411nm.

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Shear Behavior of Wide Beam-Column Joints with Slab (슬래브가 있는 넓은 보-기둥 접합부의 전단거동)

  • 안종문;최종인;신성우;이범식;박성식;양지수
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.05a
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    • pp.157-162
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    • 2003
  • An experimental investigation was conducted to study the behavior of high-strength RC wide beam-column joints with slab subjected to reversed cyclic loads under constant axial load. Six half scale interior wide beam-column assemblies representing a portion of a frame subjected to simulated seismic loading were tested, including three specimens without slab and three specimens with slab. The primary variables were compressive strength of concrete($f_ck$=285, 460kgf/$cm^2$), the ratio of the column-to-beam flexural capacity($M_r$=$\Sigma M_c / \Sigma M_b$ ; 0.77 -2.26), extended length of the column concrete($l_d$ ; 0, 12.5, 30cm), ratio of the column-to-beam width(b/H ; 1.54, 1.67). Test results are shown that (1) the behavior of specimen using high-strength concrete satisfied for required minimum ductile capacity according to increase the compressive strength, (2) the current design code and practice for interior joints(type 2) are apply to the wide beam-high strength concrete column.

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Experimental Cyclic Behavior of Precast Hybrid Beam-Column Connections with Welded Components

  • Girgin, Sadik Can;Misir, Ibrahim Serkan;Kahraman, Serap
    • International Journal of Concrete Structures and Materials
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    • v.11 no.2
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    • pp.229-245
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    • 2017
  • Post-earthquake observations revealed that seismic performance of beam-column connections in precast concrete structures affect the overall response extensively. Seismic design of precast reinforced concrete structures requires improved beam-column connections to transfer reversed load effects between structural elements. In Turkey, hybrid beam-column connections with welded components have been applied extensively in precast concrete industry for decades. Beam bottom longitudinal rebars are welded to beam end plates while top longitudinal rebars are placed to designated gaps in joint panels before casting of topping concrete in this type of connections. The paper presents the major findings of an experimental test programme including one monolithic and five precast hybrid half scale specimens representing interior beam-column connections of a moment frame of high ductility level. The required welding area between beam bottom longitudinal rebars and beam-end plates were calculated based on welding coefficients considered as a test parameter. It is observed that the maximum strain developed in the beam bottom flexural reinforcement plays an important role in the overall behavior of the connections. Two additional specimens which include unbonded lengths on the longitudinal rebars to reduce that strain demands were also tested. Strength, stiffness and energy dissipation characteristics of test specimens were investigated with respect to test variables. Seismic performances of test specimens were evaluated by obtaining damage indices.

A Reliability Analysis considering the Second Composite Effect in the To-Box Reinforcement of Deteriorated PSC Beam Bridge (PSC Beam의 박스형 보강 시 이차합성을 고려한 신뢰성해석)

  • Han Sung-Ho;Cho Chang-Joo;Bang Myung-Seok;Shin Jae-Chul
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2005.04a
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    • pp.400-407
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    • 2005
  • The reinforcing effect of modified structure of PSC beams is analyzed in this study. The PSC beams are closed by precast half panels embeding PS tendons at the bottom flange of I-bear The stiffness of box structure is larger and the PS force at half panels makes a time-dependent upward camber of superstructures. The superstructure becomes a second composite structure among 3 elements-PSC ben RC slab, PSC Panel. The time-dependent creep and shrinkage effect at PSC Panels and structural behavior is verified considering construction sequences. The optimal range of to-box reinforcing method is surveyed through reliability analysis.

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