• Title, Summary, Keyword: concrete crack

Search Result 2,161, Processing Time 0.05 seconds

Crack analysis of reinforced concrete members with and without crack queuing algorithm

  • Ng, P.L.;Ma, F.J.;Kwan, A.K.H.
    • Structural Engineering and Mechanics
    • /
    • v.70 no.1
    • /
    • pp.43-54
    • /
    • 2019
  • Due to various numerical problems, crack analysis of reinforced concrete members using the finite element method is confronting with substantial difficulties, rendering the prediction of crack patterns and crack widths a formidable task. The root cause is that the conventional analysis methods are not capable of tracking the crack sequence and accounting for the stress relief and re-distribution during cracking. To address this deficiency, the crack queuing algorithm has been proposed. Basically, at each load increment, iterations are carried out and within each iteration step, only the most critical concrete element is allowed to crack and the stress re-distribution is captured in subsequent iteration by re-formulating the cracked concrete element and re-analysing the whole concrete structure. To demonstrate the effectiveness of the crack queuing algorithm, crack analysis of concrete members tested in the literature is performed with and without the crack queuing algorithm incorporated.

Calculation of Crack Width and Crack Spacing of High-Strength Concrete Members (고강도콘크리트 부재의 균열폭 및 균열간격 계산에 관한 연구)

  • Jung, Gi-Oh;Lee, Gi-Yeol;Kim, Dae-Joong;Kim, Woo
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.227-232
    • /
    • 2002
  • This paper describes a calculation of an average crack spacing and the maximum crack width for the high-strength concrete tensile and flexural members. Based on the uniform bond stress distribution of the average steel and concrete strains over the transfer length, the crack spacing and the crack width are proposed to utilize influence of the concrete strength and the cover thickness. This analytical results presented in this paper indicate that the proposed equations can be more effectively estimated the maximum crack width and the average crack spacing of the reinforced concrete flexural and tensile members.

  • PDF

Morphological segmentation based on edge detection-II for automatic concrete crack measurement

  • Su, Tung-Ching;Yang, Ming-Der
    • Computers and Concrete
    • /
    • v.21 no.6
    • /
    • pp.727-739
    • /
    • 2018
  • Crack is the most common typical feature of concrete deterioration, so routine monitoring and health assessment become essential for identifying failures and to set up an appropriate rehabilitation strategy in order to extend the service life of concrete structures. At present, image segmentation algorithms have been applied to crack analysis based on inspection images of concrete structures. The results of crack segmentation offering crack information, including length, width, and area is helpful to assist inspectors in surface inspection of concrete structures. This study proposed an algorithm of image segmentation enhancement, named morphological segmentation based on edge detection-II (MSED-II), to concrete crack segmentation. Several concrete pavement and building surfaces were imaged as the study materials. In addition, morphological operations followed by cross-curvature evaluation (CCE), an image segmentation technique of linear patterns, were also tested to evaluate their performance in concrete crack segmentation. The result indicates that MSED-II compared to CCE can lead to better quality of concrete crack segmentation. The least area, length, and width measurement errors of the concrete cracks are 5.68%, 0.23%, and 0.00%, respectively, that proves MSED-II effective for automatic measurement of concrete cracks.

Calculation of Crack Width in SFRC Structures (강섬유보강 철근콘크리트구조물에 있어서의 균열폭 계산)

  • 강보순
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.579-584
    • /
    • 2001
  • A method is described for predicting crack with and spacing in Steel Fiber Reinforced Concrete (SFRC). The crack behavior of SFRC influenced by longitudinal reinforcement ratio, volume and type of steel fiber, strength of concrete. It can be observed from experimental results that addition of steel fiber to reinforced concrete beam reduces crack width in serviceability limit states. The proposed method predicts crack widths in cracking stage of the beam. Calculated crack widths obtained for reinforced concrete beams and different volume and type of steel fiber, strength of concrete showed good agreement with experimental results.

  • PDF

Crack Analysis of Concrete Gravity Dam Using Surface Integral Method (표면적분법을 이용한 콘크리트 댐의 균열 해석)

  • 진치섭;이영호;손기석
    • Journal of the Korea Concrete Institute
    • /
    • v.12 no.3
    • /
    • pp.31-37
    • /
    • 2000
  • When a crack is produced in a concrete structure, a micro crack zone of fracture process zone (FPZ) appears at the crack tip. To investigate the behaviour of this the micro crack zone, nonlinear fracture mechanics (NLFM) must be applied. However, when a massive concrete structure such as a concrete gravity dam is considered, the micro crack zone can be neglected and the structure can be assumed to have linear elastic fracture mechanics (LEFM) behaviour. This study is divided into two main topics : (1) Calculating stress intensity factor (SIF) at the crack tip by surface integral method and (2) Investigating the propagation of the initial crack. If the initial crack propagates, the angle of the propagation is calculated by using maximum circumferential tensile strength theory. This study, also, contains the effects of body forces and water pressures on the crack face.

Modeling of chloride diffusion in concrete considering wedge-shaped single crack and steady-state condition

  • Yang, Keun-Hyeok;Cheon, Ju Hyun;Kwon, Seung-Jun
    • Computers and Concrete
    • /
    • v.19 no.2
    • /
    • pp.211-216
    • /
    • 2017
  • Crack on concrete surface allows more rapid penetration of chlorides. Crack width and depth are dominant parameters for chloride behavior, however their effects on chloride penetration are difficult to quantify. In the present work, the previous anisotropic (1-D) model on chloride diffusion in concrete with single crack is improved considering crack shape and roughness. In the previous model, parallel-piped shape was adopted for crack shape in steady-state condition. The previous model with single crack is improved considering wedge shape of crack profile and roughness. For verifying the proposed model, concrete samples for nuclear power plant are prepared and various crack widths are induced 0.0 to 1.2 mm. The chloride diffusion coefficients in steady-state condition are evaluated and compared with simulation results. The proposed model which can handle crack shape and roughness factor is evaluated to decrease chloride diffusion and can provide more reasonable results due to reduced area of crack profile. The roughness effect on diffusion is evaluated to be 10-20% of reduction in chloride diffusion.

A Finite Element Method for Localized Failure Analysis of Concrete (콘크리트에서 국소화된 파괴해석을 위한 유한요소법)

  • 송하원;김형운;우승민
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.233-238
    • /
    • 1999
  • Localized failure analysis of concrete structures can be carried out effectively by modeling fracture process zone of concrete during crack initiation and propagation. But, the analysis techniques are still insufficient for crack modeling because of difficulties in numerical analysis procedure which describe progressive crack. In this paper, a finite element with embedded displacement discontinuity is introduced to remove the difficulties of remeshing for crack propagation in discrete crack model during progressive failure analysis of concrete structures. The performance of this so-called embedded crack approach for concrete failure analysis is verified by several analysis examples. The analysis results show that the embedded crack approach retains mesh size objectivity and can simulate localized failure under mixed mode loading. It can be concluded that the embedded crack approach cab be an effective alternate to the smeared and discrete crack approaches.

  • PDF

The Investigation of Crack widths for the Effect of Cracks on Chloride Penetration of Concrete (콘코리트 중의 염화물 침투에 영향을 미치는 균열폭에 대한 고찰)

  • Yoon, In-Seok;Erik, Schlangen;Breuged, Klaas Van
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.945-948
    • /
    • 2006
  • Chloride penetration into concrete is a hot issue of concern all over the world, notwithstanding, very few attempts have been conducted to explore the effect of cracks on choride penetration. Cracks provoke to lose a main function of watertightness of concrete and lead to reduce the service life of concrete. For this reason, it is necessary to define a critical crack width to prevent a quick chloride penetration through crack. In this study, experiment is focused on establishing a critical crack width in terms of chloride penetration. Concrete specimens with different crack widths I crack lengths have been subjected to rapid chloride migration testing. In a side of analytical solution, a simple approach to quantify the chloride diffusion coefficient of only crack zone excluding sound concrete was proposed. The result clearly showed a critical crack width of 0.03 mm. Based on the experimental results, a phenomenological model was proposed to explain the meaning of critical crack width in practical engineering. In this model, cracked concrete zone was divided into three zones. These zones corresponded to a wide crack, a zone with micro-cracks and an uncracked zone.

  • PDF

Determination of crack spacing and crack width in reinforced concrete beams

  • Piyasena, R.;Loo, Yew-Chaye;Fragomeni, Sam
    • Structural Engineering and Mechanics
    • /
    • v.15 no.2
    • /
    • pp.159-180
    • /
    • 2003
  • In this paper spacing and width of flexural cracks in reinforced concrete beams are determined using two-dimensional finite element analysis. At early loading stages on the beam the primary crack spacing is based on the slip length, which is the development length required to resist the steel stress increment that occurs at a cracked section on the formation of the first flexural crack. A semi-empirical formula is presented in this paper for the determination of the slip length for a given beam. At higher load levels, the crack spacing is based on critical crack spacing, which is defined as the particular crack spacing that would produce a concrete tensile stress equal to the flexural strength of concrete. The resulting crack width is calculated as the relative difference in extensions of steel reinforcement and adjacent concrete evaluated at the cracked section. Finally a comparative study is undertaken, which indicates that the spacing and width of cracks calculated by this method agree well with values measured by other investigators.

Characteristics of Crack Spacing and Crack Width of Continuously Reinforced Concrete Pavement Based on Long-Term Field Surveys (장기간 현장조사를 통한 연속철근 콘크리트 포장의 균열간격과 균열폭 특성 분석)

  • Oh, Han Jin;Cho, Young Kyo;Kim, Seong-Min
    • International Journal of Highway Engineering
    • /
    • v.18 no.3
    • /
    • pp.75-86
    • /
    • 2016
  • PURPOSES : The purpose of this study is to investigate characteristics of crack spacing and crack width and their relationship in continuously reinforced concrete pavement (CRCP) based on the data obtained from long-term field observations. METHODS : The crack spacings and crack widths are measured periodically over 10 years at two different CRCP sections: one with asphalt bond breaker beneath concrete slab, and the other with bonded lean concrete base beneath concrete slab. The effects of steel ratio, type of underlying layer, terminal treatment method, and seasonal temperature change on the crack characteristics are evaluated by analyzing the measured data. RESULTS : The CRCP with lean concrete base shows smaller crack spacings than those of the CRCP with asphalt bond breaker. As the steel ratio increases, both the crack spacing and crack width tend to decrease. The crack width becomes larger as the crack age increases, but once the crack age is over a certain value the crack width tends to converge. When the terminal anchor lug system is not used and the expansion joints are employed at the terminals, the crack spacings and crack widths increase near the terminal sections. The crack spacing and crack width seem to be proportional each other, but not necessarily linearly, and their relationship is more distinguished in the summer when the crack widths become smaller. CONCLUSIONS : The steel ratio, underlying layer type, terminal treatment method, and seasonal temperature change affect the characteristics of cracks and the crack spacing and crack width are related to each other.