• Title/Summary/Keyword: punching failure

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Numerical simulation of reinforced concrete slabs under missile impact

  • Thai, Duc-Kien;Kim, Seung-Eock
    • Structural Engineering and Mechanics
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    • v.53 no.3
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    • pp.455-479
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    • 2015
  • This paper presents a numerical analysis of reinforced concrete slabs under missile impact loading. The specimen used for the numerical simulation was tested by the Technical Research Center of Finland. LS-DYNA, commercial available software, is used to analyze the model. The structural components of the reinforced concrete slab, missile, and their contacts are fully modeled. Included in the analysis is material nonlinearity considering damage and failure. The results of analysis are then verified with other research results. Parametric studies with different longitudinal rebar ratios, shear bar ratios, and concrete strengths are conducted to investigate their influences on the punching behavior of slabs under the impact of a missile. Finally, efficient designs are recommended.

An Experimental Structural Performance of Steel Concrete Hybrid Deck for Bridge (교량용 강ㆍ콘크리트 합성 바닥판의 실험적 구조성능)

  • 정연주;정광회;구현본;김병석
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.05a
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    • pp.524-529
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    • 2003
  • This paper presents a experimental structural performance of steel-concrete hybrid bridge deck, which has studs to connect steel plate and concrete and T beam to improve structural performance, by steel plate shape, studs and load location. It proved that steel-concrete hybrid deck has a high structural performance and lightweight due to the efficient use of steel plate as a structural member, which has only used as formwork. In failure mode, few specimen failed at punching shear and many specimen at concrete crushing, therefore proved it has sufficient stability to punching shear which is the most frequent damage of bridge deck. Steel-concrete hybrid deck of plane steel plate has a high structural performance, and that of corrugated steel plate has a high reduction of weight.

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Punching Strength of Long-Span PSC Deck Slabs (장지간 PSC 바닥판의 정적펀칭강도)

  • Hwang Hoon Hee;Cho Chang Bin;Yoon Hye Jin;Kim Sung Tae
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.467-470
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    • 2005
  • This study was performed to evaluate the static strength of long-span PSC deck slabs. In the previous study, the minimum thickness of PSC deck slabs in the composite two-girder bridge was proposed. To examine the structural behavior and safety of the PSC deck slabs designed in accordance with the proposed minimum thickness, 1/3 scaled PSC deck slabs in the composite two-girder bridge were tested under the static loading. The test results were compared with the predicted values proposed by the code and Matsui. Test results showed ultimate static strength of the PSC deck slabs designed in accordance with the proposed minimum thickness have enough margin of safety. The static failure mode of each test specimen was punching shear mode.

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Effects of details of lattice reinforcement for punching shear strength of slab-column connections (슬래브-기둥 접합부의 뚫림 전단강도에 대한 래티스 보강상세의 영향)

  • Kim, You-Ni;Park, Hong-Gun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.17-20
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    • 2006
  • A flat plate-column connection is susceptible to brittle punching shear failure, which may result in the necessity of shear reinforcement. In previous, experimental tests were performed to study the capacity of slab-column connections strengthened with various shear reinforcement, and the capacity of the specimens with lattice reinforcement are superior to the others. In present study, to study for effects of details of lattice reinforcement, experimental studies was performed. Main parameters are the amount of lattice shear reinforcement, arrangement of lattice and the effect of flexural re-bar. And capacity of the specimen with small amount of lattice reinforcement was higher than the capacity of other shear reinforcement.

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An Experimental Study on Half Scale RC Slab Bridges Strengthened with Carbon Fiber Sheet (CFS로 보강된 모형 RC 슬래브 교량의 실험적 연구)

  • 심종성;김규선;김경민
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.04a
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    • pp.537-542
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    • 1999
  • The design methodologies for carbon fiber sheet(CFS) strengthening of RC structures are not well established yet because the structural behavior of strengthened RC structures is more complex than that of unstrengthened ones. Even though the research for the methods using CFS has beed studied, the strengthening effects and structural behaviors of strengthened structures are not systematized yet. The purpose of this study is to carry out the experimental studies on three kinds of half scale RC slab bridges and to investigate the behavior of RC slab bridges from the experimental results. Typical flexural failure occurs in the non-strengthening slab like general RC slab bridges, and also the flexural failure occurs in the all area strengthened slab with sudden rip-off failure of strengthening material by punching shear. For the case of strip type strengthened slab, flexural failure occurs, with rip-off of second strip at the base of loading point. Strengthening effect on the slab using CFS is that the strength is increased upto 7~15 percent and the crack pattern is changed.

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Punching Shear Strength of the Void Transfer Plate (중공 전이 슬래브의 뚫림 전단 강도)

  • Han, Sang-Whan;Park, Jin-Ah;Kim, Jun-Sam;Im, Ju-Hyeuk;Park, Young-Mi
    • Journal of the Korea Concrete Institute
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    • v.22 no.3
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    • pp.367-374
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    • 2010
  • The transfer slab system is a structural system that transfers the loads from the upper shear wall structure to the lower columns. This is a costly system due to a very thick slab, and the relatively high cost can be mitigated by introducing voids in the slab. However, this system of flat plate containing voids is vulnerable to brittle failure caused by punching shear in vicinity of slab-column connection. Thus, the punching shear capacity of the void system is very important. However, the current code doesn't provide a clear design provision for the strength of slabs with a void section. In this study, experimental study was conducted to investigate the punching shear strength of the void slab system. The shear strength of the specimens was predicted by current code and previous researches. In result, the punching shear strength of the void system is determined as the least value calculated at critical section located a distance d/2 from the face of the column and the center of the void section using the effective area at critical section.

Estimation of Critical Height of Embankment to Mobilize Soil Arching in Pile-supported Embankment (말뚝지지성토지반 내 지반아칭이 발달할 수 있는 한계성토고의 평가)

  • Hong, Won-Pyo;Hong, Seong-Won
    • Journal of the Korean Geotechnical Society
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    • v.26 no.11
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    • pp.89-98
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    • 2010
  • A method to design a critical height of embankments is presented so as to mobilize fully soil arching in pile-supported embankments. The behavior of the load transfer of embankment weights on pile cap beams was investigated by a series of model tests performed on pile-supported embankments with relatively wide space between cap beams. The model tests explained that the behavior of the load transfer depended very much on the height of embankments, because soil arching could be mobilized in pile-supported embankments only under enough high embankments. The measured vertical loads on cap beams coincided with the predicted ones estimated by the theoretical equations, which have been presented in the previous studies on the basis of load transfer mechanisms according to either the punching shear failure mode during low filling stage or the soil arching failure mode during high filling stage. The mechanism of the load transfer was shifted beyond a critical height of embankment from the punching shear mechanism to the soil arching mechanism. Therefore, in order to mobilize soil arching in pile-supported embankments, the embankments should be designed at least higher than the critical height. A theoretical equation to estimate the critical height could be derived by equalizing the vertical loads estimated by the load transfer mechanisms on the basis of both the punching shear and the soil arching. The derived theoretical equation could predict very well the experimental critical height of embankment.

Analytical Model for Post Tension Flat Plate Frames (포스트 텐션 플랫 플레이트 골조의 해석모델)

  • Han, Sang-Whan;Ryu, Jong-Hyuk
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.6
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    • pp.23-32
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    • 2007
  • This study developed an analytical model for predicting nonlinear behavior of PT flat plate frames having slab-column connections with and without slab bottom reinforcement passing through the column. The developed model can predict the failure sequence until punching failure occurs. For verifying the analytical model, the test results of PT flat plate slab-column connections were compared with the results of the analysis. Moreover, the results of static pushover test and shaking table test of 2 story PT flat plate frame were compared with analysis results. For evaluating seismic performance of PT flat plate frame, this study conducted nonlinear response history analysis of the 2 story PT flat plate frame with and without slab bottom reinforcement passing through the column under 1940 El Centro ground motion scaled to have pseudo spectral acceleration of 0.3, 0.5, and 0.7g at the fundamental period of the frame. This study observed that as ground motion is more intense, seismic demands for the frame having the connections without slab bottom reinforcement passing through the column are larger than those without slab bottom reinforcement.

Fatigue failure of decks in highway bridge (도로교 RC 바닥판의 피로파괴에 관한 연구)

  • 김경찬;사림신장;정상정일;권혁문
    • Proceedings of the Korea Concrete Institute Conference
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    • 1993.04a
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    • pp.169-175
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    • 1993
  • Possibility of fatigue failure in punching shear of reinforced concrete decks of highway bridges is analytically investigated by applying Matsui et al.'s experimental finding to models of 2-meter span decks designed in compliance with previous and current codes. Decks made of concrete of compressive strength of 240㎏/㎠ showed longer fatigue life than decks made of 210㎏/㎠ concrete at the same Md/U rations ; higher Md/U ratio resulted in linger fatigue life but its effect is insignificant in decks having effective depths of 14 and 15cm. Decks designed to higher load factors as specified by current codes showed longer fatigue life than decks designed to lower load factors specified by previous codes ; yet fatigue failure appeared to occur in both decks within their normal life span, thus indicating need for redefining the minimum deck thickness.

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Flexural Behavior of I-beam Composite Hollow Slabs (I형강 합성 중공바닥판의 휨거동)

  • 김대호;심창수;박창규;정영수
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.05a
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    • pp.421-426
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    • 2003
  • For the replacement of deteriorated concrete decks or wider-span slab, composite slab could be very attactive due to higher stiffness and strength. Based on the previous research, a modified I-beam composite hollow slab was suggested. In order to investigate the static flexural behavior of the proposed composite slab and to suggest its flexural design method, experiments were performed. Judging from the tests, a composite slab with I-beam having a semi-circle hole showed better structural performance. The effect of web details on the flexural stiffness was negligible. Flexural stiffness, ultimate strength, and ductility of the composite slabs were significantly greater than the RC slab due to composite action. While the failure of the RC slab was punching shear failure, the composite hollow slab showed flexural cracking and failure by yielding of the I-beams and crushing of concrete. Therefore, the current one-way design concept is appropriate for the design of I-beam composite hollow slab.

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