• Title/Summary/Keyword: Load deflection curves

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Structural response of corroded RC beams: a comprehensive damage approach

  • Finozzi, Irene Barbara Nina;Berto, Luisa;Saetta, Anna
    • Computers and Concrete
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    • v.15 no.3
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    • pp.411-436
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    • 2015
  • In this work, a comprehensive approach to model the structural behaviour of Reinforced Concrete (RC) beams subjected to reinforcement corrosion is proposed. The coupled environmental - mechanical damage model developed by some of the authors is enhanced for considering the main effects of corrosion on concrete, on composite interaction between reinforcement bars and concrete and on steel reinforcement. This approach is adopted for reproducing a set of experimental tests on RC beams with different corrosion degrees. After the simulation of the sound beams, the main parameters involved in the relationships characterizing the effects of corrosion are calibrated and tested, referring to one degraded beam. Then, in order to validate the proposed approach and to assess its ability to predict the structural response of deteriorated elements, several corroded beams are analyzed. The numerical results show a good agreement with the experimental ones: in particular, the proposed model properly predicts the structural response in terms of both failure mode and load-deflection curves, with increasing corrosion level.

Fatigue Life Prediction of Medical Lift Column utilizing Finite Element Analysis (유한요소해석을 통한 의료용 리프트 칼럼의 피로수명 예측)

  • Cheon, Hee-Jun;Cho, Jin-Rae;Yang, Hee-Jun;Lee, Shi-Bok
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.3
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    • pp.337-342
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    • 2011
  • Medical lift column controlling the vertical position while supporting heavy eccentric load should have the high fatigue strength as well as the extremely low structural deflection and vibration in order to maintain the positioning accuracy. The lift column driven by a induction motor is generally in a three-step sliding boom structure and exhibits the time-varying stress distribution according to the up-and-down motion. This study is concerned with the numerical prediction of the fatigue strength of the lift column subject to the time-varying stress caused by the up-and-down motion. The stress variation during a motion cycle is obtained by finite element analysis and the fatigue life is predicted making use of Palmgren-miner's rule and S-N curves. In order to secure the numerical analysis reliability, a 3-D FEM, model in which the detailed lift column structure and the fitting parts are fully considered, is generated and the interfaces between lift column and pads are treated by the contact condition.

Flexural Behaviors of Reinforced Concrete Beams Strengthened with Glass Fiber Sheets (유리섬유시트로 보강된 RC 보의 휨 거동에 관한 연구)

  • Kim, Seong-Do;Cho, Baik-Soon;Seong, Jin-Wook
    • Journal of the Korean Society for Railway
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    • v.12 no.3
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    • pp.388-395
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    • 2009
  • To investigate the flexural behavior of RC beams strengthened with glass fiber sheets, 1 control beam and 8 strengthened beams (4 NU-beams without U-shaped band and 4 U-beams with U-shaped band) are tested. The variables of experiment are composed of the number of glass fiber sheets and the existence of U-shaped band, etc. The maximum load was increased by 48% and 34%, and the flexural rigidity by 920% and 880% for NU-beam and U-beam, respectively, compared with those of the control beam. The ductility ratios were 1.43$\sim$2.60 for NU-beam and U-beam. The experimental results showed that the strengthening system with U-shaped band controls the premature debonding and provides a more ductile failure mode than the strengthening system without U-shaped band. It can be found from the load-deflection curves that as the number of fiber sheets is increased, the maximum strength and the flexural rigidity is increased. The experimental results are compared with the analytical results of nonlinear flexural behaviors for strengthened RC beam. The experimental and analytical results were well agreed.

Modified p-y curves to characterize the lateral behavior of helical piles

  • Hyeong-Joo, Kim;James Vincent, Reyes;Peter Rey, Dinoy;Tae-Woong, Park;Hyeong-Soo, Kim;Jun-Young, Kim
    • Geomechanics and Engineering
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    • v.31 no.5
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    • pp.505-518
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    • 2022
  • This study introduces soil resistance multipliers at locations encompassed by the zone of influence of the helix plate to consider the added lateral resistance provided to the helical pile. The zone of influence of a helix plate is a function of its diameter and serves as a boundary condition for the modified soil resistance springs. The concept is based on implementing p-multipliers as a reduction factor for piles in group action. The application of modified p-y springs in the analysis of helical piles allows for better characterization and understanding of the lateral behavior of helical piles, which will help further the development of design methods. To execute the proposed method, a finite difference program, HPCap (Helical Pile Capacity), was developed by the authors using Matlab. The program computes the deflection, shear force, bending moment, and soil resistance of the helical pile and allows the user to freely input the value of the zone of influence and Ω (a coefficient that affects the value of the p-multiplier). Results from ten full-scale lateral load tests on helical piles embedded at depths of 3.0 m with varying shaft diameters, shaft thicknesses, and helix configurations were analyzed to determine the zone of influence and the magnitude of the p-multipliers. The analysis determined that the value of the p-multipliers is influenced by the ratio between the pile embedment length and the shaft diameter (Dp), the effective helix diameter (Dh-Dp), and the zone of influence. Furthermore, the zone of influence is recommended to be 1.75 times the helix diameter (Dh). Using the numerical analysis method presented in this study, the predicted deflections of the various helical pile cases showed good agreement with the observed field test results.

Pseudostatic Analysis of Single Column/Shafts Considering Nonlinear Soil Behavior (지반의 비선형거동을 고려한 단일현장타설말뚝의 의사정적해석)

  • Lee, Joon-Kyu;Kim, Byung-Chul;Jeong, Sang-Seom;Song, Sung-Wook
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.1C
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    • pp.31-40
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    • 2008
  • This study presents the assessment of pseudostatic approach for obtaining the internal response of Single Column/Shaft subjected to earthquake loading. In numerical procedure, various lateral load transfer characteristics (p-y curve and Bi-linear curve) were used to model the nonlinear behavior of soil reactions including soil-pile interaction. The analysis using nonlinear soil model could estimate the seismic performance of soil-pile system, despite its relative simplicity. It was found that lateral behavior of single column/shaft obtained from the response displacement method was larger than those by seismic intensity method. To investigate the effects of soil-pile rigidity and pile head condition on the internal pile response, parametric studies were carried out for various soil models. The results from numerical analysis showed that lateral deflection was decreased with fixed condition of pile head and decreasing the soil-pile rigidity. The seismic analysis using Bi-linear model of JRA could reasonably predict the lateral behavior of Single Column/Shaft.

Fracture Behavior of Glass/Resin/Glass Sandwich Structures with Different Resin Thicknesses (서로 다른 레진 두께를 갖는 유리/레진/유리샌드위치 구조의 파괴거동)

  • Park, Jae-Hong;Lee, Eu-Gene;Kim, Tae-Woo;Yim, Hong-Jae;Lee, Kee-Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.12
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    • pp.1849-1856
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    • 2010
  • Glass/resin/glass laminate structures are used in the automobile, biological, and display industries. The sandwich structures are used in the micro/nanoimprint process to fabricate a variety of functional components and devices in fields such as display, optics, MEMS, and bioindustry. In the process, micrometer- or nanometer-scale patterns are transferred onto the substrate using UV curing resins. The demodling process has an important impact on productivity. In this study, we investigated the fracture behavior of glass/resin/glass laminates fabricated via UV curing. We performed measurements of the adhesion force and the interfacial energy between the mold and resin materials using the four-point flexural test. The bending-test measurements and the load-displacement curves of the laminates indicate that the fracture behavior is influenced by the interfacial energy between the mold and resin and the resin thickness.

An Experimental Study for Joints in Hybrid PSC-Steel Beam with Perfobond rib (Perfobond rib을 적용한 PSC-강 복합구조 연결부 거동에 대한 실험적 연구)

  • Won, Jeong-Hun;Park, Se-Jun;Yoon, Ji-Hyun;Kim, Sang-Hyo;Lee, Chan-Goo;Kim, Sung-Jae
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.17-20
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    • 2008
  • This study presents experimental results of Steel-PSC hybrid beams having a rear plate joint with a perfobond rib shear connector between the steel girder and the prestressed concrete girder. Three specimens of 3.9m length(3.6m span length) were tested to evaluate the flexural characteristics of the joint under the condition of the three point loading. Based on load-deflection curves and failure modes of specimens by the experimental test, it is found that the proposed joint with the perfobond rib shear connector shows the higher strength and initial stiffness and the sufficient ductility. Therefore, the suggested perfobond rib shear connector can perform effectively as the joint of the Steel-PSC hybrid structural system.

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Shear behavior and shear capacity prediction of precast concrete-encased steel beams

  • Yu, Yunlong;Yang, Yong;Xue, Yicong;Liu, Yaping
    • Steel and Composite Structures
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    • v.36 no.3
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    • pp.261-272
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    • 2020
  • A novel precast concrete-encased steel composite beam, which can be abbreviated as PCES beam, is introduced in this paper. In order to investigate the shear behavior of this PCES beam, a test of eight full-scale PCES beam specimens was carried out, in which the specimens were subjected to positive bending moment or negative bending moment, respectively. The factors which affected the shear behavior, such as the shear span-to-depth aspect ratio and the existence of concrete flange, were taken into account. During the test, the load-deflection curves of the test specimens were recorded, while the crack propagation patterns together with the failure patterns were observed as well. From the test results, it could be concluded that the tested PCES beams could all exhibit ductile shear behavior, and the innovative shear connectors between the precast concrete and cast-in-place concrete, namely the precast concrete transverse diaphragms, were verified to be effective. Then, based on the shear deformation compatibility, a theoretical model for predicting the shear capacity of the proposed PCES beams was put forward and verified to be valid with the good agreement of the shear capacities calculated using the proposed method and those from the experiments. Finally, in order to facilitate the preliminary design in practical applications, a simplified calculation method for predicting the shear capacity of the proposed PCES beams was also put forward and validated using available test results.

Equivalent Linear Stiffness Matrix of Pile Foundation for the Seismic Response Analysis of Bridges (교량의 지진응답해석을 위한 말뚝기초의 등가 선형 강도행렬)

  • 박형기;조양희
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.3
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    • pp.1-8
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    • 2001
  • Seismic design forces for bridge components may be determined by modifying elastic member forces of design earthquakes using appropriate response modification factors according to the national design code of bridges Modeling technique of pile foundation system is one of the important parameters which greatly affects the results in the process of the elastic seismic analysis of a bridge system with pile foundation. In this paper, a approximate and simplified modeling technique of a pile foundation system for the practical purposes is presented. The modeling technique is based on the stiffnesses of pile foundation during earthquake. The horizontal stiffnesses are determined from the resistance-deflection curves derived from the results of dynamic field tests using cyclic loads and the vertical stiffness includes the effects of the end bearing capacities and side friction of piles as well as the pile compliances under the expected vertical load level. The applicability of the proposed technique has been validated through the some example bridge analyses.

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The Flexural and Shear Behaviors of Steel-PSC Mixed Structural System with Front-Rear Plate Connection (전·후면판 공용방식 접합부를 갖는 강-PSC 혼합구조의 휨 및 전단거동)

  • Lho, Byeong-Cheol;Cho, Sung-Yong;Park, Hyun-Chul;Kim, Mun-Kyum
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.6
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    • pp.201-212
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    • 2007
  • This study presents experimental results of Steel-PSC mixed structural system having front-rear plate connection between Steel and Prestressed Concrete. Two kinds of Steel-PSC mixed structural system of 5.4m length were tested to evaluate flexural behaviors under four point loading, and 4 kinds of specimens with and without prestressing force at R & L type connection were tested to observe the shear behavior. Based on the test results of load-deflection curves and failure modes of specimens, it is found that the proposed L shape connection with front-rear plate connection between Steel and Prestressed Concrete has higher strength and stiffness. From the study, Steel-PSC mixed structural system with L shaped connection has a better structural performance in connection part.