Improvement of Time-Dependent Flexural Behavior in RC Members by Using Low Shrinkage-High-Strength Concrete

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Title: Improvement of Time-Dependent Flexural Behavior in RC Members by Using Low Shrinkage-High-Strength Concrete

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

Publication: Special Publication

Volume: 228

Issue:

Appears on pages(s): 1373-1396

Keywords: autogenous shrinkage; deformation; flexural crack width; high-strength concrete; RC beams; shrinkage-reducing admixture; time-dependency

Date: 6/1/2005

Abstract:
This study investigates the effectiveness of low shrinkage-high strength concrete (LS-HSC) using expansive additive and shrinkage-reducing agent with regards to the time-dependent structural performance of reinforced HSC flexural members. Design equation for evaluating the flexural crack width and deformation of RC beams considering the effect of shrinkage/expansion before loading are proposed on the basis of JSCE (Japan Society of Civil Engineers) Design Code of 2002. The results show that autogenous shrinkage of conventional HSC with no additives can significantly affect the time-dependent serviceability performance of the RC beams, while LS-HSC can markedly improve its serviceability performance. In addition, time-dependent flexural crack widths of reinforced LS-/conventional HSC beam, can be evaluated by the JSCE Code Equation, which takes into account the strain change in the reinforcement bars from the state where the stress in concrete at the depth of tension reinforcements is zero. Also, time-dependent as well as instantaneous curvatures of reinforced LS-/conventional HSC beam can be accurately calculated by the proposed equation. This equation takes into account the effect of the change in curvature due to the release of restrained-shrinkage/expansion stress at cracked section.