• 제목/요약/키워드: Ductility Ratio

검색결과 744건 처리시간 0.036초

Cyclic flexural behavior of RC members reinforced with Forta-Ferro and Polyvinyl Alcohol fibers

  • Hamed Rajabzadeh Gatabi;Habib Akbarzadeh Bengar;Murude Celikag
    • Structural Engineering and Mechanics
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    • 제87권4호
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    • pp.333-346
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    • 2023
  • This paper presents findings from an experimental study that was focused on evaluating the use of Forta-Ferro (FF) and Polyvinyl Alcohol (PVA) fibers on the response of moderate and special ductility beams under load cycles. For this reason, eight full-scale specimens, identical in geometry, were subjected to gradual cyclic loading. The specimens included two plain concrete beams with medium and special ductility, three beams with medium ductility and stirrup spacing of one-quarter the effective depth (d/4) and three beams with special ductility, and stirrup spacing of one-half the effective depth (d/2), strengthened with FF and PVA fibers separately. The use of fibers was aimed at reducing the amount of shear reinforcement in flexural members. Here, the variation of parameters including the maximum strength, ultimate strength, stiffness, ductility, damage index, energy dissipation, and equivalent damping was studied. Utilizing FF and PVA fibers improved the performance in beams with moderate ductility when compared to those beams with special ductility. Therefore, in special ductility beams, fibers can be used instead of crossties and in moderate ductility beams, fibers can be added to reduce the ratio of shear reinforcement. Furthermore, increasing the stirrup spacing in the moderate ductility beams from d/4 to d/2 and adding 0.6% FF or 1.5% PVA fibers resulted in behavior similar to those of the moderate ductility beam.

요구스펙트럼의 비탄성이력특성 -완전탄소성모델을 중심으로- (Inelastic Hysteretic Characteristics of Demand Spectrum -Focused on Elasto Perfectly Plastic Model-)

  • 이현호
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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    • pp.367-374
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    • 2000
  • This study investigates the effect of hysteretic characteristics to the Inelastic Demand Spectrum (IDS) which was expressed by an acceleration(Sa) and a displacement response spectrum (Sd). Elasto Perfectly Plastic(EPP) model is used in this study and inelastic demand spectrum (Sa vs, Sd) are obtained from a given target ductility ratio. For a given target ductility ratio IDS can be obtained by using nonlinear time history analysis of single degree of system with forth five recorded earthquake ground motions for stiff soil site. The effect EPP model under demand spectrum is investigated by ductility factor and natural frequency. According to the results obtained in this study IDS has dependency on ductility factor and natural frequency.

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고성능 철근콘크리트 보의 휨강도 및 연성능력에 관한 실험적 연구 (An Experimental Study on the Flexural Strength and Ductility Capacity of Reinforced High Performance Concrete Beams)

  • 김용부;고만영;김상우
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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    • pp.501-506
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    • 1998
  • This paper is an experimental study on the flexural strength and ductility capacity of reinforced high performance concrete beams with the concrete which has compressive strength of 600~700kg/$\textrm{cm}^2$, slump value of 20~25cm and slump-flow value of 60~70cm. Total 8 beams with different tensile reinforcement ratio and pattern of loading were tested. Form the results of reinforced high performance concrete beams, the equivalent stress block parameters proposed by MacGregor et al. or New Zealand code are recommended to use. Also, an extreme fiber concrete compressive strain of reinforced high performance concrete beams are distributed 0.0033~0.0048. In reinforced high performance concrete beams, reinforcement ratio in order to insure curvature ductility index 2 and 4 propose by ACI code should be less than those of reinforced normal strength concrete beams.

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내부 구속 중공 R.C 교각의 연성도 평가 (Ductility Evaluations of Internally Confined Hollow R.C Piers)

  • 한택희;조인석;강영종;이명섭
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 2005년도 학술발표회 논문집
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    • pp.353-360
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    • 2005
  • When the weight if a concrete member makes problems, or when the cost of the concrete is relatively high, it may be economical to use a hollow concrete member. But a hollow R.C Pier may have poor ductility because of the brittle failure at the inner face of the hollow R.C Pier. This brittle failure results from the absence of the confinement at the inner face of the hollow R.C Pier. To avoid this brittle failure an internally confined hollow R.C Pier was developed. Test results show that the energy ductility ratio of a internally confined hollow R.C Pier have a superior energy ductility ratio to a general hollow R.C Pier.

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주상복합구조에서 전이보와 내부기둥 접합부의 반복횡하중 실험 (Cyclic Loading Test of Interior Deep-Beam Lower-Column Joint in Upper-shear Wall Lower-Frame Structure)

  • 이한선;김상연;고동우;권기혁;최성모
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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    • pp.446-451
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    • 2000
  • In case of strong earthquake, upper-sheat wall lowe-frame structures show the weak-story failure at lower part. Where we should guarantee sufficient strength, energy dissipation capacity and ductility. In this study, a typical structure was selected for a prototype and four 1:2.5 scaled models, representing the subassemblages including the interior column and the deep beam, were constructed. Experimental parameters include transverse reinforcement ratio and axial force. The non- linear behavior of the subassemblages subjected to the cyclic lateral displac-ement were evaluated through investigation of the ultimate strength, ductility, load-deformation characteristics. From the results of the tests on 4 specimens, it is concluded that the strength increased as the axial force increased and the ductility increased as the transverse reinforcement ratio increased.

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철근콘크리트 보-기둥 접합부의전단거동에 관한 실험적 연구 (An Experimental Study on Shear Behaviorof Reinforced Concrete Beam-Column Joints)

  • 김진영;오기종;이정윤
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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    • pp.105-108
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    • 2006
  • Current ACI and AIJ guidelines only address the importance of the concrete strength and geometry of the joint. There are no significant attention paid to other variables. In addition, the current design code doesn't predict the ductility of the beam-column assemblies. The former researcher proposed the analytical model to predict the shear strength of the joint panel as well as the ductility of the beam-column assemblies in year 2004. In this study, the experiments to investigate shear behavior of reinforced concrete beam-column joints and to verify proposed model were carried out, based on the experimental results. As the formal researcher proposed, the factor K (K=0.5), the ductility of BJ-failure was predicted reasonably when the transverse reinforcement ratio exceeded 0.0186. However, the proposed equation showed a large discrepancies in the ductility estimating when transverse reinforcement ratio was below 0.0186.

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Flexural ductility of RC beam sections at high strain rates

  • Pandey, Akhilesh K.
    • Computers and Concrete
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    • 제12권4호
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    • pp.537-552
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    • 2013
  • Computation of flexural ductility of reinforced concrete beam sections has been proposed by taking into account strain rate sensitive constitutive behavior of concrete and steel, confinement of core concrete and degradation of cover concrete during load reversal under earthquake loading. The estimate of flexural ductility of reinforced concrete rectangular sections has been made for a wide range of tension and compression steel ratios for confined and unconfined concrete at a strain rate varying from $3.3{\times}10^{-5}$ to 1.0/sec encountered during normal and earthquake loading. The parametric studies indicated that flexural ductility factor decreases at increasing strain rates. Percentage decrease is more for a richer mix concrete with the similar reinforcement. The confinement effect has marked influence on flexural ductility and increase in ductility is more than twice for confined concrete (0.6 percent volumetric ratio of transverse steel) compared to unconfined concrete. The provisions in various codes for achieving ductility in moment resisting frames have been discussed.

Evaluation of local and global ductility relationships for seismic assessment of regular masonry-infilled reinforced concrete frames using a coefficient-based method

  • Su, R.K.L.;Tang, T.O.;Lee, C.L.
    • Earthquakes and Structures
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    • 제5권1호
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    • pp.1-22
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    • 2013
  • Soft storey failure mechanism is a common collapse mode for masonry-infilled (MI) reinforced concrete (RC) buildings subjected to severe earthquakes. Simple analytical equations correlating global with local ductility demands are derived from pushover (PO) analyses for seismic assessments of regular MI RC frames, considering the critical interstorey drift ratio, number of storeys and lateral loading configurations. The reliability of the equations is investigated using incremental dynamic analyses for MI RC frames of up to 7 storeys. Using the analytical ductility relationship and a coefficient-based method (CBM), the response spectral accelerations and period shift factors of low-rise MI RC frames are computed. The results are verified through published shake table test results. In general applications, the analytical ductility relationships thus derived can be used to bypass the onerous PO analysis while accurately predicting the local ductility demands for seismic assessment of regular MI RC frames.

지진하중 특성에 따른 구조물의 에너지 요구량 (Seismic Energy Demand of Structures Depending on Characteristics of Earthquakes)

  • 최현훈;김진구
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 2005년도 학술발표회 논문집
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    • pp.121-128
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    • 2005
  • In this study the influences of ground motion characteristics and structural properties on energy demands were evaluated using 100 earthquake ground motions recorded in different soil conditions, and the results were compared with those of previous works. Results show that ductility ratios and the site conditions have significant influence on input energy. The ratio of hysteretic to input energy is considerably influenced by the ductility ratio and damping ratio, while site condition has minor effects.

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철근콘크리트 휨부재의 최소철근비에 대한 고찰 (An Examination of the Minimum Reinforcement Ratio for Reinforced Concrete Flexural Members)

  • 최승원
    • 한국구조물진단유지관리공학회 논문집
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    • 제21권6호
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    • pp.35-43
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    • 2017
  • 철근콘크리트 휨부재의 최소철근비는 부재의 취성 파괴를 방지하기 중요한 설계 인자이다. 콘크리트구조기준과 도로교설계기준에서 사용되는 최소철근비는 단면의 유효 깊이 및 모멘트 팔길이에 대한 가정을 통해 산정되었다. 따라서 이 연구에서는 재료 모델과 힘의 평형 관계를 통해 합리적으로 최소철근비를 산정할 수 있는 방법을 제안하였다. 연구 결과 도로교설계기준의 포물-사각형 곡선을 통해 산정된 최소 철근비는 현재 설계 기준에 의한 최소철근비의 약 52~80% 수준으로 산정되어 경제적인 설계가 가능한 것으로 나타났다. 또한, 재료 모델을 통한 최소철근량이 배치된 부재의 연성 능력은 현재 설계 기준에 의한 값의 약 89% 수준으로 평가되었으나, 부재의 연성도는 7 이상으로 충분한 연성능력을 보였다. 따라서 제안된 포물-사각형 곡선을 통한 최소철근비는 휨부재 설계의 이론적 합리성 뿐만 아니라 안전성 및 경제성을 확보할 수 있는 것으로 나타났다.