• Title/Summary/Keyword: shear cap

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Enhancement of Subgrade Stiffness Profiling by Incorporating Rayleigh and Love Waves into the Common-Array-Profiling(CAP) SASW Technique (레일레이파.러브파의 동시활용과 CAP SASW 기법 적용에 의한 지반 전단강성 평가의 고품질화)

  • Chang, Dae-Woo;Joh, Sung-Ho;Kang, Tae-Ho;Koh, Hak-Song
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.338-345
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    • 2005
  • Recently, surface-wave methods have been widely used for site investigation due to economic advantage and improved reliability. Specially, the Spectral-Analysis-of-Surface-Wave (SASW) method has been used to evaluate soil properties in geotechnical engineering. In determination of subgrade stiffness by SASW measurements, only the vertical Rayleigh waves have been used. This study proposed a framework to determine shear-wave velocity profiles by using vertical and horizontal Rayleigh waves and Love wave all together. In addition, the Common-Array-Profiling(CAP) SASW method was employed, which subgrade stiffness of profile the local material under two fixed receivers. The procedure proposed in this study was verified by comparing the shear-wave velocity profiles with the shear-wave velocity profiles of downhole testing at two geotechnical sites.

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Analysis and Design of Approach Bridge Pile Cap in Incheon Bridge Project (인천대교 접속교 파일캡의 해석과 설계)

  • Song, Jong-Young;Shin, Hyun-Yang;Choi, Kyu-Yong;Song, Chang-Hee;Lee, Tae-Yeol;Shim, Ih-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.221-224
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    • 2006
  • For structural engineers, design of pile cap causes difficulties since design of this member is not specifically addressed by codes. In general, pile cap is considered as deep beam and designed for shear and moment at specified critical section. This is called as traditional section method. However, many international design codes suggest the application of strut tie method for better design of this member. In this paper, a brief application of strut tie method to the design check of pile cap structure designed by section method is presented. Unlike well known pile cap with single column, the example pile cap has two columns. In order to find out proper load path under various load condition, three dimensional finite element method was carried out. The result indicates that provided reinforcement by traditional section method has sufficient capacity to meet the design requirements.

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Performance assessment of precast concrete pier cap system

  • Kim, T.H.;Kim, Y.J.;Shin, H.M.
    • Computers and Concrete
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    • v.13 no.4
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    • pp.501-516
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    • 2014
  • The purpose of this study was to investigate the performance of precast concrete pier cap system. The proposed precast pier cap provides an alternative to current cast-in-place systems, particularly for projects in which a reduced construction time is desired. Five large-scale pier cap specimens were constructed and tested under quasistatic monotonic loading. The computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used for the analysis of reinforced concrete structures. A bonded tendon element is used based on the finite element method, and can represent the interaction between the tendon and concrete of a prestressed concrete member. A joint element is used in order to predict the inelastic behaviors of segmental joints with a shear key. This study documents the testing of the precast concrete pier cap system under monotonic loading and presents conclusions and design recommendations based on the experimental and analytical findings. Additional full-scale experimental research is needed to refine and confirm design details, especially for actual detailing employed in the field.

A Parameter Analysis for Pull-out and Push-out Behavior of Steel Pipe Pile Cap with the Open Type Perfobond (개방형 퍼포본드로 보강된 강관말뚝머리의 인발 및 압발거동에 관한 매개변수 해석)

  • Kim, Young-Ho;Kang, Jae-Yoon;Yoo, Seung-Woon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.6A
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    • pp.661-669
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    • 2009
  • Various kinds of shear connectors such as headed stud, channel, perforated steel plate and others are commonly used to transfer stress and conduct composite performance in steel concrete composite structures, and many researches have been conducted to improve the characteristics of different types of shear connectors. It is focused in this study on the pull-out and pushout performance of steel pipe pile cap with the open type perfobond for the composite connection to the spread footing. A parameter analysis was conducted, using ABAQUS, a nonlinear finite element analysis program, to obtain data for determining the characteristics of the structure and to allow various parametric analyses of steel pipe cap with the open perfobond.

Evaluation of Stiffness Profile for a Subgrade Cross-Section by the CAP(Common-Array-Profiling)-SASW Technique (CAP SASW 기법에 의한 지반단면의 전단강성구조 평가)

  • Joh Sung-Ho;Jang Dae-Woo;Kang Tae-Ho;Lee Il-Wha
    • Journal of the Korean Geotechnical Society
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    • v.21 no.4
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    • pp.71-81
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    • 2005
  • Surface wave techniques were initially based on 2-D plane waves and were later improved to the techniques based the 3-D based cylindrical waves. However, body-wave interference, near-field effect and limited technology in surface wave measurements restricted the use of 3-D cylindrical waves to the 1-D evaluation of subgrade stiffness. In this study, by the numerical simulation of SASW measurements, the dispersion properties of surface waves including vertical, horizontal Rayleigh waves and Love waves were thoroughly investigated in the 3-D domain, and a new filter criteria to minimize the near-field effect was established, which led to CAP (common-array-profiling)-SASW technique. The CAP-SASW technique enabled the evaluation of subgrade stiffness fur a specific subgrade segment, not for a whole section of measurement array. Therefore, a contour plot of subgrade stiffness with a ground-truth quality can be obtained by the CAP-SASW technique. The procedure proposed in this study was verified by comparing the shear-wave velocity profiles with the shear-wave velocity profiles of downhole testing at two geotechnical sites.

The suggestion of Steel Plate-Concrete Composite Beam Shape with Bolts (볼트 체결형 강판-콘크리트 합성보의 형상 제안)

  • Cho, Tae-Gu;Choi, Byong-Jeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.7
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    • pp.305-314
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    • 2018
  • The steel-plate concrete composite beam is composed of a steel plate, concrete and a shear connector to combine the two inhomogeneous materials. In general, the steel plate is assembled by welding an existing composite beam. In this study, a new steel-plate concrete composite (SPCC) beam was developed to reduce the size of the shear connector and improve its workability. The SPCC beam was composed of folded steel plates and concrete, without any shear connector. The folded steel plate was assembled with high strength bolts instead of welding. To improve the workability in field construction, a hat-shaped cap was attached in the junction with the slab. Monotonic two-point load testing was conducted under displacement control mode. The flexural strength of the SPCC beam specimen was calculated to be 76% of that of the complete composite beam by using the plastic stress distribution method and strain compatibility method. The cap acted as the stud and accessory. The synthesis rate could be increased by controlling the gap of the cap, and the bending performance could be evaluated by using the strain fitting method considering the synthesis rate of the SPCC beam.

Flexural Strength Evaluation of Steel Plate-Concrete Composite Beam using Bolted (절곡 강판을 볼트로 체결한 강판-콘크리트 합성보의 휨강도 평가)

  • Han, Myoung-Hwan;Choi, Byong-Jeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.6
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    • pp.126-136
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    • 2018
  • A steel-plate concrete composite beam is composed of a steel plate, concrete and shear connector to combine inhomogeneous two materials. The steel plate is assembled by welding an existing composite beam. In this study, new steel-plate concrete composite beam, called a SPC Beam, was developed to reduce the shear connector and improve the workability. The SPC Beam was composed of folding steel plates and concrete, without a shear connector. The folding steel plate was assembled using high strength bolt instead of welding. To improve the workability in field construction, a hat-shaped Cap was attached to the junction with a slab. Monotonic load testing under two points was conducted under displacement control mode. The flexural strength of the specimen for positive moment and negative moment was calculated using the plastic stress distribution method. The test results showed that the flexural strength of the new SPC Beam had 80% of the strength of a complete composite beam. In addition, increasing the composite ratio was possible through clearance controls of the cap. In this study, the performance of the SPC Beam was verified through additional experiments and analyses with the cross-sectional shape and cap as variables, because the representative shape in the positive negative moment region is targeted.

Evaluation of Structural Performance of Precast Modular Pier Cap (프리캐스트 모듈러 피어캡의 구조성능 평가)

  • Kim, Dong Wook;Shim, Chang Su
    • Journal of the Korea Concrete Institute
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    • v.27 no.1
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    • pp.55-63
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    • 2015
  • Prefabrication technologies are making bridge construction safer and less disruptive to the environment and traveling public, making bridge designs more constructible and, improving the quality and durability by shifting site work to a more controllable environment. Modular bridge substructures with concrete-filled steel tube (CFT) piers and composite pier caps were suggested to realize accelerated bridge construction. The precast segmental pier cap consists of a composite pier table and precast prestressed segments on the table. The pier table has embedded steel section to mitigate stress concentration at the connection by small tubes. Each bridge pier has four or six CFT columns which connect to the pier cap. Shear strength of the pier cap was obtained by extending vertical reinforcing bars from the table to the precast segment. Transverse prestressing was introduced to control tensile stresses by service loadings. Structural performance of the proposed modular system was evaluated by static tests. Design requirements of the composite pier cap were satisfied by continuous reinforcing bars and prestressing tendons. Standardized modular substructures can be effectively utilized for the fast replacement or construction of bridges.

Finite Element Analysis Reinforced Concrete Slab Bridge Considering Elastic deformations of Reinforced Concrete T-type Piers (T형 교각의 탄성변형을 고려한 슬래브교의 유한요소 해석)

  • 이성철;윤동열
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2000.04b
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    • pp.100-110
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    • 2000
  • In practical design of girder bridges or reinforced concrete slab bridges with T-type piers, it is usually assumed that vertical movements of superstructures are completely restrained at the locations of bearings(shoes) on a cap beam of the pier, The resulting vertical reactions are applied to the bearing for the calculation of bending moments and shear forces in the cap beam. However, in reality, the overhang parts of the cap beam will deform under the dead load of superstructures and the live load so that it may act as an elastic foundation. Due to the settlement of the elastic foundation, the actual distribution of the reactions at the bearings along the cap beam may be different from that obtained under the assumption that the vertical movements are fixed at the bearings. In the present study, investigated is the effects of elastic deformations of the T-type pier on the distribution of reactions at the bearings along the cap beam through 3-dimensional finite element analysis. Herein, for this purpose the whole structural system including the superstructure and piers as well is analyzed. It appears that the conventional practice which neglects the elastic deformations of the cap beam exhibits considerably different distributions of the reactions as compared with those obtained from the present finite element analysis. It is, therefore, recommended that in order to assess the reactions at bearings correctly the whole structural system be analyzed using 3-dimensional finite element analysis.

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Theoretical Analysis of Embankment Loads Acting on Piles (성토지지말뚝에 작용하는 연직하중의 이론해석)

  • 홍원표;이재호;전성권
    • Journal of the Korean Geotechnical Society
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    • v.16 no.1
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    • pp.131-143
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    • 2000
  • Several theoretical analyses are performed to predict the vertical load on embankment piles with cap beams. The piles are installed in a row in soft ground below the embankment and the cap beams are placed perpendicular to the longitudinal axis of the embankment. Two failure mechanisms such as the soil arching failure and the punching shear failure are investigated according to the failure pattern in embankment on soft ground supported by piles with cap beams. The soil arching can be developed when the space between cap beams is narrow and/or the embankment is high enough. In the investigation of the soil arching failure, the stability in the crown of the arch is compared with that above the cap beams. The factors affecting the load transfer in the embankment fill by soil arching are the space between cap beams, the width of cap beams and the soil parameters of the embankment fill. The portion of the embankment load carried by cap beams decreases with increment of the space between cap beams, while it increases with the embankment height, the width of cap beams, the internal friction angle and cohesion of the embankment fill. Thus, the factors affecting load transfer in embankment should be appropriately decided in order to maximize the effect of embankment load transfer by piles.

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