• Title/Summary/Keyword: cracking analysis

Search Result 997, Processing Time 0.026 seconds

Effect of Separation Strip on the Concrete Slabs in High Rise Building (고층건물 콘크리트 슬래브에서 분리대의 효과)

  • 김한수;조석희
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2000.04b
    • /
    • pp.238-245
    • /
    • 2000
  • Separation strips are temporary joints to prevent crack due to stress induced by shrinkage. In this study, an analysis procedure considering separation strip is proposed to decide proper casting time of separation strip and cracking stresses of the example building slabs are calculated using this procedure. The result of the example high rise building shows that the percentage of cracking stress to the modulus of fracture is 43.4% when closing of separation strip are 30 days after placing the slab, so it is enough time for the separation strip in each floor to absorb the effects of shrinkage.

  • PDF

Bond Stress-Slip Model for Serviceability Verification on Structural Concrete Members (철근콘크리트 부재의 사용성능 검증을 위한 부착응력-미끄럼 모델)

  • Lee, Gi-Yeol;Yang, Jun-Ho;Chung, Won-Yong;Rho, Sam-Young;Kim, Dae-Joong;Kim, Woo
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2009.05a
    • /
    • pp.17-18
    • /
    • 2009
  • This research defined slip function using cracking behavior, bond characteristics and numerical analysis of cracking stabilized reinforced concrete member, and proposed a bond stres-slip model.

  • PDF

Heterogeneous Catalysis of Iso-Octane over Cation Exchanged Mordenite Surfaces

  • Chong, Paul-Joe
    • Bulletin of the Korean Chemical Society
    • /
    • v.5 no.2
    • /
    • pp.79-82
    • /
    • 1984
  • This study concerns about catalyic cracking of iso-octane over cation ($Cd^{2+},\;Ca^{2+}\;and\;La^{3+}$) exchange mordenites. It deals with mordenite shape selectivity and with kinetics of this catalytic reaction. The striking feature was that over the region of cracking temperature investigated, 523-665K, the yield of isobutene was predominant, relative to that of larger or smaller carbon chain(s). This permits kinetic analysis of the heterogeneous catalytic system in terms of the modified pulse-version microcatalytic chromatography. The observed activation energy ($E_a,\;KJ\;mol^{-1}$) was found to be 46 for Cd-M, 57 for Ca-M and 59 for La-M, respectively.

Performance Estimation of Tunnel Lining Concrete Reinforced Steel Fiber (강섬유 보강 터널 라이닝 콘크리트의 성능 평가)

  • Jeon, Chan-Ki;Kim, Su-Man;Lee, Myung-Soo;Lee, Jong-Eun;Jeon, Joong-Kyu
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2005.11a
    • /
    • pp.579-582
    • /
    • 2005
  • Tunnel lining is the final support of a tunnel and reflects the results of the interaction between ground and support system. Recently it is very difficult to support and manage the tunnel because the cracks on tunnel lining cause problems in supporting and managing tunnels. Therefore the analysis of the cracks is quite strongly required. The major role played by the steel fiber occurs in the post-cracking zone, in which the fibers bridge across the cracked matrix. Because of its improved ability to bridging cracks, steel fiber reinforcement concrete(SFRC) has better crack properties than that of reinforced concrete. In this study, mechanical behaviour of a tunnel lining was examined by model tests. The model tests were carried out under various conditions taking different loading shapes, thicknesses and leakage of lining, and volume content of steel fiber. From these model test, the cracking load, the failure load, defection and cracking position and type were examined and the characteristics of deformation and failure for tunnel lining were estimated and researched.

  • PDF

A Numerical Study on Plastic Shrinkage Cracking of Concrete Slabs (콘크리트 슬래브의 소성수축균열에 대한 해석적 연구)

  • Kwak-Hyo-Gyoung;Ha, Soo-Jun
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2005.11a
    • /
    • pp.785-788
    • /
    • 2005
  • In this paper, the influence of many factors related to the concrete mixture and the weather condition on plastic shrinkage cracking are analyzed through parametric studies using the numerical models introduced in the companion paper. First of all, through a systematic calculation of bleeding, the relationship between the bleeding constants and concrete mixture is proposed on the basis of the experimental data obtained by many researchers. Moreover, an equation, which can directly determine a critical point at which the evaporation and bleeding is balanced, is introduced, and the efficiency of the introduced equation is verified through the correlation study between the obtained results by the introduced equation and those by the rigorous analyses. The introduced equation can effectively be used to predict and to prevent plastic shrinkage cracking without any rigorous analysis and, in advance, to cope with the sudden changes in the concrete mixture and/or weather condition.

  • PDF

Prediction of Cover Concrete Cracking due to Chloride Induced Corrosion in Concrete Structures (콘크리트 구조물의 염해부식에 따른 덮개콘크리트의 균열예측)

  • Lim, Dong-Woo;Lee, Chang-Hong;Song, Ha-Won
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2009.05a
    • /
    • pp.291-292
    • /
    • 2009
  • In this study, an analysis of cover concrete cracking exposed to the chloride attack was performed based on newly defined durability limit states. Using the methodology in this paper, the prediction of cover concrete cracking and subsequent spalling can be used for the prediction of corrosion induced serviceability degradation of concrete structures subjected chloride attack.

  • PDF

Probabilistic Analysis of Reinforced Concrete Beam and Slab Deflections Using Monte Carlo Simulation

  • Choi, Bong-Seob;Kwon, Young-Wung
    • KCI Concrete Journal
    • /
    • v.12 no.2
    • /
    • pp.11-21
    • /
    • 2000
  • It is not easy to correctly predict deflections of reinforced concrete beams and one-way slabs due to the variability of parameters involved in the calculation of deflections. Monte Carlo simulation is used to assess the variability of deflections with known statistical data and probability distributions of variables. A deterministic deflection value is obtained using the layered beam model based on the finite element approach in which a finite element is divided into a number of layers over the depth. The model takes into account nonlinear effects such as cracking, creep and shrinkage. Statistical parameters were obtained from the literature. For the assessment of variability of deflections, 12 cases of one-way slabs and T-beams are designed on the basis of ultimate moment capacity. Several results of a probabilistic study are presented to indicate general trends indicated by results and demonstrate the effect of certain design parameters on the variability of deflections. From simulation results, the variability of deflections relies primarily on the ratio of applied moment to cracking moment and the corre-sponding reinforcement ratio.

  • PDF

Development of Concrete Material Model for Nonlinear Analysis of Nuclear Containment Building (원전 격납건물 비선형 해석을 위할 콘크리트 재료모델 개발)

  • 이홍표;전영선;서정문;신재철
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2004.10a
    • /
    • pp.312-319
    • /
    • 2004
  • This paper is mai y focused to develop new concrete material model such as ultimate failure surface in compression-compression region, hardening rule and cracking criteria which are basically used in the nonlinear finite element analysis of nuclear prestressed concrete containment building. From the Kepri's experimental results, failure surface of the concrete based on the elasto-plastic material model is modified and new cracking criteria is proposed. Nonlinear FE analysis program using a new material model is implemented to analysis plane concrete. Finally, numerical simulation to compare the performance of the new material model with experimental results is employed. The numerical results by the proposed model in this study agree very well with the experimental data.

  • PDF

Equivalent Elastic Modulus for Lined Pipe Analysis (Lined Pipe 해석을 위한 등가 탄성계수 계산)

  • 정진한;최재승;하대홍
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2000.11a
    • /
    • pp.547-550
    • /
    • 2000
  • The steel pipe for fluid catalytic cracking(FCC) unit. petroleum refinery, is lined with refractory to protect the system from high-temperature of the internal flow. The property of the refractory has an effect upon the stress analysis of FCC unit. Because 1-D pipe element or 3-D shell element are usually used in commercial codes of stress analysis to evaluate the structural soundness, the equivalent elastic modulus considering steel and refractory should be applied. In the research, the theoretical method to obtain the value of the equivalent property is introduced and then the stress analysis is carried out with the part of FCC unit.

  • PDF

Finite Element Analysis on Concrete Fracture using Homogenized Crack Model (혼합균열모델을 적응한 콘크리트 파괴의 유한요소해석)

  • 송하원;방춘석
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2003.04a
    • /
    • pp.137-144
    • /
    • 2003
  • Since quasi-brittle material like concrete shows strain localization behavior accompanied by strain softening, a numerical drawback such as mesh sensitivity is appeared in the finite element analysis. In this study, a homogenized crack model which overcomes the drawback and considers rate discontinuity in the constitutive equation is proposed for modeling of cracking in concrete and its propagation in strain softening regime. Then, a series of finite element analysis of the concrete under various loading conditions has been performed. From comparison of analysis results with experimental data, it is shown that failure behavior due to localized cracking of concrete under both compressive loading condition and tensile loading condition is well predicted by the homogenized crack model.

  • PDF