Numerical Analysis of the Effect of Shrinkage on Flexural Deformation and Crack Width


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Title: Numerical Analysis of the Effect of Shrinkage on Flexural Deformation and Crack Width

Author(s): I. Ujike, R. Sato, I. Maruyama, M. Tanimura, and M. Suzuki

Publication: Special Publication

Volume: 246


Appears on pages(s): 201-216

Keywords: deformation; fictitious crack model; flexural crack width; numerical analysis; reinforced concrete beam; shrinkage; tension softening

Date: 9/1/2007

The effect of shrinkage on short-term and long-term flexural deformation and crack width of structural concrete members is investigated numerically and experimentally. The numerical analysis was performed by solving simultaneous differential equations relating to bond slip based on bond stress-slip relationship. The equations were formulated for an element between adjacent two cracks, taking shrinkage, creep, time dependent of bond and tension softening based on fictitious crack model into consideration. To verify the present method, load tests were carried out on structural concrete members with 200mm wide x 250mm high section made of conventional high shrinkage concrete and expansive high strength concrete, in which curvature and crack width were measured in a constant bending moment zone with 800mm length. In addition to this, creep and shrinkage tests were also performed. The following conclusions are drawn from the present study; (1) Tension in concrete at a cracked section contributes dominantly to decreasing the stress in a tension reinforcing bar resulting in enhancing the flexural stiffness and in decreasing the flexural crack width, when the stress in the tension reinforcing bar is below 150 N/mm2 and the tension reinforcing bar ratio is below 1.5%. (2) Flexural crack widths increase with time after the application of sustained loading mainly due to loss of tension stiffening at cracked section, which is caused by shrinkage. (3) The above conclusions are explained by the present method.