• Title/Summary/Keyword: punching shear failure

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Punching shear behavior of recycled aggregate concrete

  • Dan, Saikat;Chaudhary, Manpreet;Barai, Sudhirkumar V.
    • Computers and Concrete
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    • v.21 no.3
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    • pp.321-333
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    • 2018
  • Flat-slabs, being a significant structural component, not only reduce the dead load of the structure but also reduce the amount of concrete required for construction. Moreover the use of recycled aggregates lowers the impact of large scale construction to nearby ecosystems. Recycled aggregate based concrete being a quasi-brittle material shows enormous cracking during failure. Crack growth in flat-slabs is mostly in sliding mode (Mode II). Therefore sufficient sections need to be provided for resistance against such failure modes. The main objective of the paper is to numerically determine the ultimate load carrying capacity of two self-similar flat-slab specimens and validate the results experimentally for the natural aggregate as well as recycled aggregate based concrete. Punching shear experiments are carried out on circular flat-slab specimen on a rigid circular knife-edge support built out of both normal (NAC) and recycled aggregate concrete (RAC, with full replacement). Uniaxial compression and bending tests have been conducted on cubes, cylinders and prisms using both types of concrete (NAC and RAC) for its material characterization and use in the numerical scheme. The numerical simulations have been conducted in ABAQUS (a known finite element software package). Eight noded solid elements have been used to model the flat slab and material properties have been considered from experimental tests. The inbuilt Concrete Damaged Plasticity model of ABAQUS has been used to monitor crack propagation in the specimen during numerical simulations.

Experimental Study for Concrete Base to Sleeve connection of Hybrid Substructure for Offshore Wind Turbine (하이브리드 해상풍력발전 지지구조물의 콘크리트 베이스-슬리브 연결부에 대한 실험 연구)

  • Lee, Jeong-Hwa;Byun, Nam-Joo;Kim, Seong-Hwan;Park, Jae-Hyun;Kang, Young-Jong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.1
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    • pp.79-87
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    • 2016
  • In this paper, concrete base to sleeve connections of hybrid substructures for offshore wind turbines were suggested and investigated experimentally. Punching shear strength tests with well-instrumented three connections under different reinforcement ratios and loading conditions were conducted to investigate the punching shear strength and the behavior of the concrete base to a sleeve connection. The test results showed that the punching strength and stiffness of the connections are affected mainly by the reinforcement ratios. The loading conditions with an axial load and proportional moment cannot affect the stiffness but affect the strength of the connections because of the axial load-moment interaction. The punching shear failure and critical section of the each test specimen are also discussed.

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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Punching Shear Behavior of High-strength Lightweight Concrete Slab Under Concentrated Load (집중하중을 받는 고강도 경량콘크리트 바닥판의 펀칭전단 거동)

  • Cho, Sun-Kyu;Kwark, Jong-Won;Lee, Jong-Min;Moon, Dae-Joong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.1A
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    • pp.219-228
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    • 2006
  • Because of the advantage of light weight, lightweight concrete is frequently applied to long-span bridges and high-rise buildings. In the country, there is not enough experience for the long-span bridges using lightweight concrete. This paper presents results of an experimental study on the punching shear strength of high-strength lightweight concrete slabs. Four test slabs are fabricated using high-strength lightweight concrete and normalweight concrete and at the center of the test slabs, simulated wheel load is applied until failure. The compressive strengths of lightweight concrete and normalweight concrete are 47MPa and 32MPa, respectively. The test results show the failure mode of all specimens are punching shear and the behaviors of high-strength lightweight concrete slabs are very similar to that of normalweight concrete slabs. Based on the test results, it is discussed the safety and serviceability of high-strength lightweight concrete bridge decks.

Dynamic punching shear tests of flat slab-column joints with 5D steel fibers

  • Alvarado, Yezid A.;Torres, Benjamin;Buitrago, Manuel;Ruiz, Daniel M.;Torres, Sergio Y.;Alvarez, Ramon A.
    • Structural Engineering and Mechanics
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    • v.81 no.3
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    • pp.281-292
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    • 2022
  • This study aimed to analyze the dynamic punching shear performance of slab-column joints under cyclic loads with the use of double-hooked end (5D) steel fibers. Structural systems such as slab-column joints are widely found in infrastructures. The susceptibility to collapse of such structures when submitted to seismic loads is highly dependent on the structural performance of the slab-column connections. For this reason, the punching capacity of reinforced concrete (RC) structures has been the subject of a great number of studies. Steel fibers are used to achieve a certain degree of ductility under seismic loads. In this context, 5D steel hooked fibers provide high levels of fiber anchoring, tensile strength and ductility. However, only limited research has been carried out on the performance under cyclic loads of concrete structural members containing steel fibers. This study covers this gap with experimental testing of five different full-scale subassemblies of RC slab-column joints: one without punching reinforcement, one with conventional punching reinforcement and three with 5D steel fibers. The subassemblies were tested under cyclic loading, which consisted of applying increasing lateral displacement cycles, such as in seismic situations, with a constant axial load on the column. This set of cycles was repeated for increasing axial loads on the column until failure. The results showed that 5D steel fiber subassemblies: i) had a greater capacity to dissipate energy, ii) improved punching shear strength and stiffness degradation under cyclic loads; and iii) increased cyclic loading capacity.

Estimation of Fatigue safety for PSC Bridge Decks (PSC 바닥판의 피로 안전성 평가)

  • 김영진;이정우;주봉철;김병석;박성용;이필구
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.05a
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    • pp.525-530
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    • 2002
  • This study is peformed to propose the slab deck for the composite bridge with two girders. Considering the characteristics of the long span and the construction conditions in korea, a cast-in-place PSC deck was proposed for that bridge. To examine structural behaviors and safety of the proposed PSC deck, two real scale partitions of deck(12m$\times$3.2m) were tested under the fatigue loading. In the test, the failure mode and behaviors of each specimen, and the ultimate load carrying capacity of the two-girder-bridge deck were identified. Generally, the failure of concrete bridge deck is caused by the local punching shear stress resulting from the moving wheel load. Even though its ultimate flexural capacity is sufficiently larger than the demand, it could be failed by the punching shear fatigue. Therefore, the fatigue safety of the proposed PSC deck should be checked.

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Failure Mechanism for Pull-Out Capacity of Headed Reinforcement (Head Reinforcement 인발강도를 위한 파괴 메캐니즘)

  • 홍성걸;최동욱;권순영
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.05a
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    • pp.233-238
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    • 2002
  • This study presents failure mechanisms for the pull-out strength of headed reinforcement for upper bound solution based on the limit theorem. The failure mechanisms to be presented follow the failure surface pattern of punching shear failure found in the joints of slab with a column. Several failure surfaces of the mechanisms have different characteristics for dissipation works and these mechanisms are able to interpret the role of bar details surrounding headed reinforcement.

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The Effect of Anchorage with Shear Reinforcement in Flat Plate System (플랫 플레이트 구조에서 전단보강체의 정착성능에 따른 전단보강효과)

  • Choi, Chang-Sik;Bae, Baek-Il;Choi, Yun-Cheul;Choi, Hyun-Ki
    • Journal of the Korea Concrete Institute
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    • v.24 no.6
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    • pp.667-675
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    • 2012
  • Flat plate are being used more in buildings requiring a high level of technical installations or in buildings needing changeable room arrangements during their life time such as office buildings. The main problem in flat plate is its weak resistance against a punching failure at its slab-column connections. Therefore, in this research, an experimental study on full-scale interior slab-column connection was performed. Three types of shear reinforcements were tested to prevent brittle punching shear failure that could lead to collapse of the structure. A series of four flat plate specimens including a specimen without shear reinforcement and three specimens with shear reinforcements were tested. The slabs were tested up to failure using monotonic vertical shear loading. The presences of the shear reinforcements substantially increased punching shear capacity and ductility of the interior slabcolumn connections. The test results showed that a slab that did not have enough bond length failed before shear reinforcement yielded due to anchorage slip. Also, FEM analyses were performed to study an effect of slab thickness and concrete compressive strength on the flat plate slab. The analytical study results were used to propose a method to calculate performance capacity of shear reinforcement in slab-column connection.

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.