• Title/Summary/Keyword: Cyclic loads

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A Study on Flexural and Shear Behavior of the Structure with Steel Plate Concrete to Reinforced Concrete Member's Connection (철근 콘크리트와 강판 콘크리트 간 이질접합부로 구성된 구조물의 휨 및 전단거동 특성 연구)

  • Hwang, Kyeong Min;Lee, Kyung Jin;Lee, Jong Bo;Won, Deok Hee
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.32 no.5A
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    • pp.267-275
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    • 2012
  • This paper describes the experimental study on the structural behavior of the joint plane between a RC(Reinforced Concrete) wall and a SC(Steel Plate Concrete) wall under out-of plane flexural loads and in-plane shear loads. The test specimens were produced with L and I shape to assess efficiently flexural and shear behavior of the structures. In order to consider dynamic loads such as earthquake, cyclic loading tests were carried out. As results of the out-of plane flexural tests, ductile failure mode of vertical bars was shown under a push load and the failure load was more than nominal strength of the specimen. And the latter test was performed to verify the variation which was composition presence of horizontal bars in the SC member. The test results showed that capacity of the specimens was more than their nominal strength regardless of composition presence of horizontal bars.

Fatigue Fracture Assessment of Honeycomb Composite Side-Wall Panel Joint for the KTX Tilting Car Body (틸팅차량용 KTX 차체의 하니컴복합재 측벽판 체결부의 피로파괴평가)

  • Jeong, Dal-Woo;Kim, Jung-Seok;Choi, Nak-Sam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.1
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    • pp.55-60
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    • 2010
  • The honeycomb composite joint structure designed for application to a tilting KTX railroad car body is subjected to bending loads of a cantilever type. Honeycomb sandwich composite panel-joint attached in the real tilting car body was fabricated and sectioned as several beam-joint specimens for the bending test. The fracture behaviors of these specimens under static loads were different from those under cyclic loads. Static bending loads caused shear deformation and fracture in the honeycomb core region, while fatigue cyclic bend loading caused delamination along the interface between the composite skin and the honeycomb core, and/or caused a fracture in the welded part jointed with the steel under-frame. These fracture behaviors could occur in other industrial honeycomb composite joints with similar sub-structures, and be used for improving design parameters of a honeycomb composite joint structure.

Case Studies of Nonlinear Response Structural Optimization Using Equivalent Loads (등가하중법을 이용한 비선형 반응 구조최적설계 사례연구)

  • Kim, Yong-Il;Park, Gyung-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.11
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    • pp.1059-1068
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    • 2007
  • Nonlinear response structural optimization is performed using equivalent loads (NROEL). Nonlinear response optimization is extremely cost because many nonlinear analyses are required. In NROEL, the external loads are transformed to the equivalent loads (EL) for linear static analysis and linear response optimization is carried out based on the EL in a cyclic manner until the convergence criteria are satisfied. EL is the load set which generates the same response field of linear analysis as that of nonlinear analysis. The primitive from of theory has been published. In this research, the theory is investigated with large scale example problems. Four examples are solved by using NROEL. Conventional optimization with sensitivity analysis using the finite difference method (FDM) is also applied to the same examples. Moreover, response surface optimization method is applied to the last two examples. The results of the optimizations are compared. In nonlinear response optimization of large scale problems, hundreds (or even thousands) of nonlinear analyses are expected to satisfy the convergence criteria. However, in nonlinear response optimization using equivalent loads, only tens of nonlinear analyses are required. The results are discussed and the usefulness of NROEL is presented.

Analysis of Cyclic Loading Transferred Mechanism on Geosynthetic-Reinforced and Pile-Supported Embankment (토목섬유로 보강된 성토지지말뚝 시스템의 반복하중 전이 메커니즘 분석)

  • Lee, Sung-Jee;Yoo, Min-Taek;Lee, Su-Hyung;Baek, Min-Cheol;Lee, Il-Wha
    • Journal of the Korean Geotechnical Society
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    • v.32 no.12
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    • pp.79-91
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    • 2016
  • Geosynthetic-reinforced and Pile-supported (GRPS) embankment method is widely used to construct structures on soft ground due to restraining residual settlement and their rapid construction. However, effect of cyclic loading has not been established although some countries suggest design methods through many studies. In this paper, cyclic loading tests were conducted to analyze dynamic load transfer characteristics of pile-supported embankment reinforced with geosynthetics. A series of 3 case full scale model tests which were non-reinforced, one-layer-reinforced, two-layer reinforced with geosynthetics were performed on piled embankments. In these series of tests, the height of embankment and pile spacing were selected according to EBGEO (2010) standard in Germany. As a result of the vertical load parts on the pile and on the geosynthetic reinforcement measured separately, cyclic loads transferred by only arching effect decreased with strength geosynthetic-reinforced case. However, final loads on the pile showed no differences among the cases. These results conflict with previous studies that reinforcement with geosynthetics increases transfer load concentrated on piles. In addition, it is observed that the load transferred to pile decreases at the beginning of cycle number due to reduction of arching effected by cyclic loading. Based on these results, transferred mechanism for cyclic load on GRPS system has been presented.

Load-resisting characteristics for RC Retrofitting Columns under Cyclic Loads (반복하중을 받는 RC 기둥보강부재의 내력특성실험)

  • 김종임;홍남표;윤정배;정일영
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10a
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    • pp.589-596
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    • 1998
  • Experimental studies are investigated for RC column retrofitting under cyclic load. Design considerations are jacketing of steel plate of carbon fiber with epoxy bonding, use of unbonded plate, additional concrete grouting, ratio of additional longitudinal steel reinforcement and longitudinal configuration of additional ties. Investigated results are 1) jacketing and additional reinforcements are effective for strengthening, 2) use of additional grouting is less effective with respect to increased section. Future studies are needed to evaluate the requirements about additional reinforcements for member stress level, 3) bond between original and additional grout concrete.

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Recycled aggregate concrete filled steel SHS beam-columns subjected to cyclic loading

  • Yang, You-Fu;Zhu, Lin-Tao
    • Steel and Composite Structures
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    • v.9 no.1
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    • pp.19-38
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    • 2009
  • The present paper provides test data to evaluate the seismic performance of recycled aggregate concrete (RAC) filled steel square hollow section (SHS) beam-columns. Fifteen specimens, including 12 RAC filled steel tubular (RACFST) columns and 3 reference conventional concrete filled steel tubular (CFST) columns, were tested under reversed cyclic flexural loading while subjected to constant axially compressive load. The test parameters include: (1) axial load level (n), from 0.05 to 0.47; and (2) recycled coarse aggregate replacement ratio (r), from 0 to 50%. It was found that, generally, the seismic performance of RACFST columns was similar to that of the reference conventional CFST columns, and RACFST columns exhibited high levels of bearing capacity and ductility. Comparisons are made with predicted RACFST beam-column bearing capacities and flexural stiffness using current design codes. A theoretical model for conventional CFST beam-columns is employed in this paper for square RACFST beam-columns. The predicted load versus deformation hysteretic curves are found to exhibit satisfactory agreement with test results.

Fatigue Damage Assessment for Steel Structures Subjected to Earthquake (지진에 대한 강구조물의 피로손상도 추정법)

  • Song, Jong Keol;Yun, Chung Bang;Lee, Dong Guen
    • Journal of Korean Society of Steel Construction
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    • v.9 no.1 s.30
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    • pp.95-105
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    • 1997
  • Structures subjected to strong seismic excitation may undergo inelastic deformation cycles. The resulting cumulative fatigue damage process reduces the ability of structures and components to withstand seismic loads. Yet, the present earthquake resistance design methods focus mainly on the maximum displacement ductility, ignoring the effect of the cyclic responses. The damage parameters closely related to the cumulative damage need to be properly reflected on the aseismic design methods. In this study, two cumulative damage assessment methods derived from the plastic fatigue theory are investigated. The one is based on the hysteretic ductility amplitude, and the other is based on the dissipated hysteretic energy. Both methods can consider the maximum ductility and the cyclic behavior of structural response. The validity of two damage methods has been examined for single degree of freedom structures with various natural frequencies against two different earthquake excitations.

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Improved numerical approach for the bond-slip behavior under cyclic loads

  • Kwak, H.G.
    • Structural Engineering and Mechanics
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    • v.5 no.5
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    • pp.663-677
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    • 1997
  • Bond-slip behavior between reinforcement and concrete under push-pull cyclic loadings is numerically investigated based on a reinforcement model proposed in this paper. The equivalent reinforcing steel model considering the bond-slip effect without taking double nodes is derived through the equilibrium at each node of steel and the compatibility condition between steel and concrete. Besides a specific transformation algorithm is composed to transfer the forces and displacements from the nodes of the steel element to the nodes of the concrete element. This model first results in an effective use in the case of complex steel arrangements where the steel elements cross the sides of the concrete elements and second turns the impossibility into a possibility in consideration of the bond-slip effect in three dimensional finite element analysis. Finally, the correlation studies between numerical and experimental results under the continuously repeated large deformation stages demonstrate the validity of developed reinforcing steel model and adopted algorithms.

Modeling of reinforced concrete structural members for engineering purposes

  • Mazars, Jacky;Grange, Stephane
    • Computers and Concrete
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    • v.16 no.5
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    • pp.683-701
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    • 2015
  • When approached using nonlinear finite element (FE) techniques, structural analyses generate, for real RC structures, large complex numerical problems. Damage is a major part of concrete behavior, and the discretization technique is critical to limiting the size of the problem. Based on previous work, the ${\mu}$ damage model has been designed to activate the various damage effects correlated with monotonic and cyclic loading, including unilateral effects. Assumptions are formulated to simplify constitutive relationships while still allowing for a correct description of the main nonlinear effects. After presenting classical 2D finite element applications on structural elements, an enhanced simplified FE description including a damage description and based on the use of multi-fiber beam elements is provided. Improvements to this description are introduced both to prevent dependency on mesh size as damage evolves and to take into account specific phenomena (permanent strains and damping, steel-concrete debonding). Applications on RC structures subjected to cyclic loads are discussed, and results lead to justifying the various concepts and assumptions explained.

Cyclic Seismic Performance of High-Strength Bolted-Steel Beam Splice (반복재하 실험에 의한 고력볼트 철골 보 이음부의 내진거동 연구)

  • 이철호
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1998.10a
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    • pp.57-64
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    • 1998
  • This paper presents the cyclic seismic performance of slip-critically designed, high-strength bolted-beam splice in steel moment frame. Before the moment connection reaching its plastic strength, unexpected premature slippage occurred at the slip-critically designed beam splice during the test. The experimentally observed frictional coefficients were as low as about 50% to 60% of nominal (code) value. Nevertheless, the bearing type behavior mobilized after the slippage transferred the increasing cyclic loads successfully, i.e., the consequence of slippage into bearing was not catastrophic to the connection behavior. The test result seems to indicate that the traditional beam splice design basing upon (bolt-hole deducted) effective flange area criterion may not be sufficient in developing the plastic strength of moment connections under severe earthquake loading. New procedure for achieving slip-critical beam splice design is proposed based on capacity design concept.

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