• Title, Summary, Keyword: Approach slab

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Ultimate Strength of Composite Beams with Unreinforced Web Opening (유공 합성보의 강도식에 관한 연구)

  • 김창호;박종원;김희구
    • Journal of the Korea Concrete Institute
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    • v.12 no.5
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    • pp.101-110
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    • 2000
  • A practical approach of calculating the ultimate strength of composite beams with unreinforced web opning is proposed through shear behavioral tests. In this method, the slab shear contribution at the opening is calculated as the smaller value of the pullout capacity of shear connector at the high moment end and the one way shear capacity of slab. A simple interaction equation is used to predict the ultimate strength under simultaneous bending moment and shear force. Strength prediction by the proposed method is compared with previous test results and the predictions by other analytical methods. The comparison shows that the proposed method predicts the ultimate capacity with resonable accuracy.

Probabilistic Analysis of Reinforced Concrete Beam and Slab Deflections Using Monte Carlo Simulation

  • Choi, Bong-Seob;Kwon, Young-Wung
    • KCI Concrete Journal
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    • v.12 no.2
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    • pp.11-21
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    • 2000
  • It is not easy to correctly predict deflections of reinforced concrete beams and one-way slabs due to the variability of parameters involved in the calculation of deflections. Monte Carlo simulation is used to assess the variability of deflections with known statistical data and probability distributions of variables. A deterministic deflection value is obtained using the layered beam model based on the finite element approach in which a finite element is divided into a number of layers over the depth. The model takes into account nonlinear effects such as cracking, creep and shrinkage. Statistical parameters were obtained from the literature. For the assessment of variability of deflections, 12 cases of one-way slabs and T-beams are designed on the basis of ultimate moment capacity. Several results of a probabilistic study are presented to indicate general trends indicated by results and demonstrate the effect of certain design parameters on the variability of deflections. From simulation results, the variability of deflections relies primarily on the ratio of applied moment to cracking moment and the corre-sponding reinforcement ratio.

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Time dependent service load behaviour of prestressed composite tee beams

  • Uy, Brian
    • Structural Engineering and Mechanics
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    • v.5 no.3
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    • pp.307-327
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    • 1997
  • This paper is concerned with the time dependent service load behaviour of prestressed composite tee beams. The effects of creep and shrinkage of the concrete slab are modelled using the age adjusted effective modulus method and a relaxation approach. The tendon strain is determined considering compatibility of deformations and equilibrium of forces between the tendon and the composite tee beam. A parametric study is undertaken to study the influence of various aspects on the stress, strain and deformations of the concrete slab, steel beam and prestressing tendon. The effect of loading type and tendon relaxation has also been considered for various types of prestressing tendon materials. Recommendations are then made in relation to adequate span to depth ratios for varying levels of prestressing force.

A New Model for Predicting Width Spread in a Roughing Mill - Part I: Application to Dog-bone Shaped Inlet Cross (조압연 공정의 판 폭 퍼짐 예측 모델 - Part I : 도그 본 형상에 적용)

  • Lee, D.H.;Lee, K.B.;Hwang, S.M.
    • Transactions of Materials Processing
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    • v.23 no.3
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    • pp.139-144
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    • 2014
  • In the current study, we present a new model for predicting width spread of a slab with a dog-bone shaped cross section during rolling in the roughing train of a hot strip mill. The approach is based on the extremum principle for a rigid plastic material and a three dimensional admissible velocity field. The upper bound theorem is used for calculating the width spread of the slab. The prediction accuracy of the proposed model is examined through comparison with the predictions from 3-D finite element (FE) process simulations.

A Permittivity Measurement of Dielectric Slabs Using a Parallel Plate Waveguide (평행판 도파관을 이용한 유전율 측정 방법)

  • Cho, Gyo-Yeong;Park, Wee-Sang
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.12 no.2
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    • pp.199-203
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    • 2012
  • This paper introduces a simple new procedure approach to determine the permittivity of dielectric slabs. The method uses a parallel plate waveguide which supports a TEM mode. The presence of the dielectric slab placed at the bottom of the waveguide makes the speed of the TEM wave slower. The relationship between the change of the speed and the permittivity of the dielectric slab allows the determination of the permittivity. The relationship is analyzed electromagnetically, and the results of measurements are in good agreement with the analysis.

A Study on the Evaluation of Design Moments of R/C Slab by the Finite Element Method (유한요소법(有限要素法)을 이용한 철근(鐵筋)콘크리트 슬래브의 설계(設計)모멘트 산정에 관한 소고(小考))

  • Lee, Sung Woo
    • Journal of The Korean Society of Civil Engineers
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    • v.8 no.3
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    • pp.21-29
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    • 1988
  • Evaluation of accurate design moments in two directions is a primary concern in designing R/C Slab. For this purpose, the use of finite element method utilizing isoparametric plate element is proposed. An example of the simply supported slab shows that the results agree well wth those from elastic plate theory throughout the span. The finite element solutions are also compared with those from equivalent frame method in a flat plate example. It is indicated that the distribution of total moment through the width of design strip using the ACI coefficients is unreasonable. In contrary to this, for the same strip model, the finite element method gives accurate moments in two directions. The proposed method can be applied to any geometric configuration of the slab system, thus the approach is considered to be much advantageous and improved one compared with existing methods.

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Nonlinear Analysis for Negative Moment Distribution of MRS Slab End Joints (비선형 해석에 의한 MRS 슬래브 단부 접합부의 모멘트 분포 연구)

  • Moon, Jeong-Ho;Oh, Young-Hun;Lim, Jae-Hyung
    • Journal of the Korea Concrete Institute
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    • v.23 no.2
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    • pp.177-184
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    • 2011
  • This paper describes an analytical study on the design approach of PC system with continuous connections at member ends. In multi-ribbed moment resisting slab (MRS) system, double tee members are connected continuously over inverted tee beams with the continuous reinforcements placed within topping concrete. Thus, negative moments are concentrated within the narrow connection area. In order to propose a design method, experimental results of the companion study were examined using detailed nonlinear analysis. Then nonlinear static analysis was used to evaluate the partial continuity effect and the moment redistribution mechanism. Material and cross sectional properties were obtained from experimental results of the companion study. Plastic hinge properties for nonlinear static analysis were modeled with cracking moment, nominal moment, corresponding member deformations, etc. The analysis results showed that a large amount of negative moment of MRS slab can be reduced by applying partial continuity and moment redistribution in MRS joint.

Seismic Performance Evaluation of Flat Column Dry Wall System and Wall Slab System Structures (무량복합 및 벽식 구조시스템의 내진성능평가)

  • Kang, Hyungoo;Lee, Minhee;Kim, Jinkoo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.3
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    • pp.259-266
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    • 2012
  • In this paper the seismic performance of a flat plate wall system structure was evaluated based on the ATC-63 approach, and the results were compared with those of a wall slab structure having the same size. As analysis model structures, a twelve story flat plate wall structure and a wall slab structure were designed based on the KBC-2009, and their seismic performances and collapse behaviors were evaluated by nonlinear static and incremental dynamic analyses(IDA). It was observed that the flat plate wall structure was designed with smaller amount of reinforced concrete, and showed slightly larger displacement response compared with those of the wall slab structure. The collapse margin ratios of the two structures obtained from the incremental dynamic analyses satisfied the limit states specified in the ATC-63, and the structures turned out to have enough capacity to resist the design level seismic load.

A mechanical model of vehicle-slab track coupled system with differential subgrade settlement

  • Guo, Yu;Zhai, Wanming;Sun, Yu
    • Structural Engineering and Mechanics
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    • v.66 no.1
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    • pp.15-25
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    • 2018
  • Post-construction subgrade settlement especially differential settlement, has become a key issue in construction and operation of non-ballasted track on high-speed railway soil subgrade, which may also affect the dynamic performance of passing trains. To estimate the effect of differential subgrade settlement on the mechanical behaviors of the vehicle-slab track system, a detailed model considering nonlinear subgrade support and initial track state due to track self-weight is developed. Accordingly, analysis aiming at a typical high-speed vehicle coupled with a deteriorated slab track owing to differential subgrade settlement is carried out, in terms of two aspects: (i) determination of an initial mapping relationship between subgrade settlement and track deflections as well as contact state between track and subgrade based on a semi-analytical method; (ii) simulation of dynamic performance of the coupled system by employing a time integration approach. The investigation indicates that subgrade settlement results in additional track irregularity, and locally, the contact between the concrete track and the soil subgrade is prone to failure. Moreover, wheel-rail interaction is significantly exacerbated by the track degradation and abnormal responses occur as a result of the unsupported areas. Distributions of interlaminar contact forces in track system vary dramatically due to the combined effect of track deterioration and dynamic load. These may not only intensify the dynamic responses of the coupled system, but also have impacts on the long-term behavior of the track components.

A Study on Settlement according to Height and Ground stiffness on the MSEW on the IPM Bridge (토압분리형 교량의 보강토옹벽의 높이와 기초지반 강성에 따른 침하량 검토)

  • Park, Min-Cheol
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.5
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    • pp.399-409
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    • 2018
  • The mechanically stabilized earth wall (MSEW) of the IPM bridge is an important structure that constitutes the bridge, and supports the horizontal earth pressure and approach slab. Therefore, it is necessary to carefully analyze the settlement of MSEW of the IPM bridge. This study examined the settlement according to the height and ground stiffness on the MSEW on the IPM Bridge. According to the design guideline, the IPM Bridge (2016) was designed to have a height of 4.0 ~ 10.0m and the elastic settlement was calculated. The base area and the grounding pressure of the MSE wall increased linearly with the height, and the elastic settlement also increased linearly. In addition, the stiffness of the foundations satisfying the allowable settlement of the approach slab is a N value of 35 or more. The settlement of finite element analysis was estimated to be smaller than the elastic settlement, and the stiffness of the foundation ground satisfied the allowable settlement of the approach slab above N value of 20. Because the elastic settlement of the MSEW of the IPM Bridge was overestimated, it will be necessary to examine it carefully by finite element analysis.