• 제목/요약/키워드: Failure strength analysis

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Seismic Performance of Post Tensioned Flat Plate Frames according to Slab Bottom Reinforcement (하부철근 유무에 따른 PT 플랫 플레이트 골조의 내진성능)

  • Park, Young-Mi;HwangBo, Jin;Ryu, Jong-Hyuk;Han, Sang-Whan
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.233-236
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    • 2008
  • This study evaluates the seismic performance of post-tensioned(PT) flat plate frames with or without slab bottom reinforcement. For this purpose, 3 and 9 story PT flat plate frames designed only considering gravity loads. This study conducts a nonlinear static pushover analysis. This study use an analytical model which is able to represent punching shear failure and fracture mechanism. The analytical results showed that seismic performance of PT flat plate frame is strongly influenced by the existence of slab bottom reinforcement through column. By placing slab bottom reinforcement in PT flat plate frame, lateral strength and deformation capacity are significantly increased.

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Interfacial Evaluation of Modified Jute and Hemp Fibers/Polypropylene (PP)-Maleic Anhydride Polypropylene Copolymers (PP-MAPP) Composites Using Micromechanical Test and Nondestructive Acoustic Emission (Micromechanical 시험법과 음향방출을 이용한 Flax 와 Hemp 섬유 강화 에폭시 복합재료의 계명 물성 평가)

  • Son, Tran Quang;Hwang, Byung-Sun;Park, Joung-Man
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.11a
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    • pp.157-160
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    • 2005
  • The surface energies and acid-base interaction between the untreated and treated Jute or Hemp fibers and different matrix compositions of polypropylene-maleic anhydride polypropylene copolymers (PP-MAPP) were investigated using dynamic contact angle measurement. The contribution of the acid-base property into the interfacial adhesion of the natural fibers/matrix systems were characterized by calculating the work adhesion coming from the acid-base interaction. On the other hand, microfailure mechanism of both single Jute and Hemp fiber bundles were investigated using the combination of single fiber tensile test and acoustic emission. Distinctly different micro failure modes of the different natural fiber/polypropylene systems wet ε observed using optical microscope and determined indirectly by AE and their FFT analysis.

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Structural performance of ferrocement beams reinforced with composite materials

  • Shaheen, Yousry B.I.;Eltaly, Boshra A.;Abdul-Fataha, Samer G.
    • Structural Engineering and Mechanics
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    • v.50 no.6
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    • pp.817-834
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    • 2014
  • An experimental program was designed in the current work to examine the structural behavior of ferrocement beams reinforced with composite materials under three point loadings up to failure. The experimental program comprised casting and testing of twelve ferrocement beams having the dimensions of 120 mm width, 200 mm depth and 1600 mm length. The twelve beams were different in the type of reinforcements; steel bars, traditional wire meshes (welded and expanded wire meshes) and composite materials (fiberglass wire meshes and polypropylene wire meshes). The flexural performances of the all tested beams in terms of strength, ductility, cracking behavior and energy absorption were investigated. Also all the tested beams were simulated using ANSYS program. The results of the experimental tests concluded that the beam with fiber glass meshes gives the lowest first crack load and ultimate load. The ferrocement beam reinforced with four layers of welded wire meshes has better structural behavior than those beams reinforced with other types of wire meshes. Also the beams reinforced with metal wire meshes give smaller cracks width in comparing with those reinforced with non-metal wire meshes. Also the Finite Element (FE) simulations gave good results comparing with the experimental results.

Simplified P-M interaction curve model for reinforced concrete columns exposed to standard fire

  • Lee, Deuck Hang;Cheon, Na-Rae;Kim, Minsu;Lee, Jungmin;Oh, Jae-Yuel;Kim, Kang Su
    • Computers and Concrete
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    • v.19 no.5
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    • pp.545-553
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    • 2017
  • In the authors' previous study, an axial force-flexural moment (P-M) interaction curve model was proposed to evaluate fire-resisting performances of reinforced concrete (RC) column members. The proposed method appeared to properly consider the axial and flexural strength degradations including the secondary moment effects in RC columns due to fire damage. However, the detailed P-M interaction curve model proposed in the authors' previous study requires somewhat complex computational procedures and iterative calculations, which makes it difficult to be used for practical design in its current form. Thus, the aim of this study was to develop a simplified P-M interaction curve model of RC columns exposed to fire considering the effects of fire damage on the material performances and magnitudes of secondary moments. The simplified P-M interaction model proposed in this study was verified using 66 column fire test results collected from literature, and the verification results showed that the proposed simplified method can provide an adequate analysis accuracy of the failure loads and fire-resisting times of the RC column specimens.

Behaviour of bolted connections in concrete-filled steel tubular beam-column joints

  • Beena, Kumari;Naveen, Kwatra;Shruti, Sharma
    • Steel and Composite Structures
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    • v.25 no.4
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    • pp.443-456
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    • 2017
  • Many authors have established the usefulness of concrete filled steel tubular (CFST) sections as compression members while few have proved their utility as flexural members. To explore their prospective as part of CFST frame structures, two types of connections using extended end plate and seat angle are proposed for exterior joints of CFST beams and CFST columns. To investigate the performance and failure modes of the proposed bolted connections subjected to static loads, an experimental program has been executed involving ten specimens of exterior beam-to-column joints subjected to monotonically increasing load applied at the tip of beam, the performance is appraised in terms of load deformation behaviour of joints. The test parameters varied are the beam section type, type and diameter of bolts. To validate the experimental behaviour of the proposed connections in CFST beam-column joints, finite element analysis for the applied load has been performed using software ATENA-3D and the results of the proposed models are compared with experimental results. The experimental results obtained agree that the proposed CFST beam-column connections perform in a semi-rigid and partial strength mode as per specification of EC3.

Effect of biaxial stress state on seismic fragility of concrete gravity dams

  • Sen, Ufuk;Okeil, Ayman M.
    • Earthquakes and Structures
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    • v.18 no.3
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    • pp.285-296
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    • 2020
  • Dams are important structures for management of water supply for irrigation or drinking, flood control, and electricity generation. In seismic regions, the structural safety of concrete gravity dams is important due to the high potential of life and economic loss if they fail. Therefore, the seismic analysis of existing dams in seismically active regions is crucial for predicting responses of dams to ground motions. In this paper, earthquake response of concrete gravity dams is investigated using the finite element (FE) method. The FE model accounts for dam-water-foundation rock interaction by considering compressible water, flexible foundation effects, and absorptive reservoir bottom materials. Several uncertainties regarding structural attributes of the dam and external actions are considered to obtain the fragility curves of the dam-water-foundation rock system. The structural uncertainties are sampled using the Latin Hypercube Sampling method. The Pine Flat Dam in the Central Valley of Fresno County, California, is selected to demonstrate the methodology for several limit states. The fragility curves for base sliding, and excessive deformation limit states are obtained by performing non-linear time history analyses. Tensile cracking including the complex state of stress that occurs in dams was also considered. Normal, Log-Normal and Weibull distribution types are considered as possible fits for fragility curves. It was found that the effect of the minimum principal stress on tensile strength is insignificant. It is also found that the probability of failure of tensile cracking is higher than that for base sliding of the dam. Furthermore, the loss of reservoir control is unlikely for a moderate earthquake.

Static Behavio in Weak Axis of FRP Bridge Deck Filled With a Foam (폼 충전 FRP 바닥판의 약축방향 정적거동 특성)

  • Zi Goang-Seup;Kim Byeong-Min;Hwang Yoon-Koog;Lee Young-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2006.04a
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    • pp.906-913
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    • 2006
  • The failure mechanism of a hollow bridge deck which is made of glass fiber reinforced polymer(GFRP) is investigated using both experiments and analysis. While the load-displacement behavior of the deck in the transverse direction shows a strong nonlinearity even in its initial response with relatively small magnitude of loads. In order to imporve the structural behavior of the deck in the transverse direction, we suggested that the empty space of the bridge deck is filled with a foam and investigated experimentally the static behavior of the orthotropic bridge deck which is made from GFRP and polyurethane foam. It is found that although the elastic modulus of the foam compared to that of the GFRP is about the order of $10^{-3}$, the structural behaviors in the weak axis such as nominal strength, stiffness, etc. are greatly improved. Owing to the low mass density of the foam used in this study, the bridge deck is still light enough with the improved structural properties.

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Reliability Analysis for Stress Corrosion Cracking of Suspension Bridge Wires (현수교케이블의 응력부식에 관한 신뢰성해석)

  • Taejun;Andrzej S. Nowak
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.04a
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    • pp.537-544
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    • 2003
  • This paper deals with stress corrosion cracking behavior of high strength steel exposed to marine environments. The objective is to determine the time to failure as a function of hydrogen concentration and tensile stress in the wires. A crack growth curve is modeled using finite element method (FEM) program. The coupled hydrogen diffusion-stress analyses of SCC were programmed separately. The first part is calculating stress and stress intensity /sup 1)/factor of a cylindrical shell, prestressing tendon or suspension bridge wires, from the initiation of cracks to rupture. Virtual crack extension method, contour integral method, and crack tip elements are used for the calculation of stresses in front of the crack tip. Comparisons of the result show a good agreement with the analytical equations and wire tests. The second part of the study deals with the programming of hydrogen diffusion, affected by hydrostatic stress, calculated at the location of boundary of plastic area around the crack tip. The results of paper can be used in the design and management of prestressed structures, cable stayed and suspension bridges. Time dependent correlated parallel reliabilities of a cable, composed of 36 wires, were evaluated by the consideration of the deterioration of stress corrosion cracking.

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A Numerical Investigation on End Bearing Capacity of Single Pile Installed in Fractured Rock Mass (절리암반에 설치된 단말뚝기초의 선단지지력에 관한 수치해석 연구)

  • Kim, Tae-Jung;Yoo, Chung-Sik
    • Journal of the Korean Geotechnical Society
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    • v.29 no.1
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    • pp.61-70
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    • 2013
  • This paper presents the results of a two-dimensional finite element analysis of end bearing capacity of single pile installed in fractured rock mass. A number of cases were analyzed using Hoek-Brown criterion that can consider the condition of rock joints. Considering a wide range of joint conditions in which the pile is embedded into the rock, GSI was set as a main parameter. And the effects of pile diameter, unconfined compressive strength of rock and Hoek-Brown constant $m_0$ were considered. Based on parameter study, end bearing load factor graphs were suggested.

The failure analysis of patch bonded repair on Al 6061-T6 alloy structures with cracked bolt hole (볼트 균열 홀을 갖는 알루미늄 6061-T6 합금의 패치 본딩 보수/보강 부위에 대한 파괴역학적 해석에 관한 연구)

  • Yoon, Young-Ki;Kim, Guk-Gi;Park, Jong-Jun;Yoon, Hi-Seak
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.148-152
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    • 2000
  • The aluminum alloy 6061-T6 has been successfully used in structural applications especially the pressure vessel of the Advanced Neutron Source research reactor. And aluminum alloys, including 6061-T6, have a face-centered-cubic crystals structure. Under normal circumstances face-centered-cubic crystal structures do not exhibit cleavage fractures even at very lo9w temperatures. In aluminum-based structures, plates frequently find use as connecting links. Mechanical fasteners are often utilized in instances where ease of application, familiarity with fabrication processes, and severe dynamic loading are of concern. Plates frequently find use as connecting elements in structures built from aluminum alloys. Many structural elements employ mechanical fasteners. Twenty and twenty aluminum alloy 6061-T6 plates, representing four different bolt patterns, were mechanically deformed. And variable materials such as A1 6061-T6, Al 2024-T3, Carbon/Epoxy, Glass/Epoxy Composite and Woven fiber composite, are used as patch materials. From this experiment, it has been shown that the strength of patch-repaired specimens is different with the patch materials.

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