INVESTIGATION OF TIME-DEPENDENT DEFORMATION OF RC BEAMS WITH FLEXURAL CRACKS GENERATED AT EARLY AGE CONSIDERING SHRINKAGE PROPERTY OF CONCRETE

• KOMATSU Satoshi

  横浜国立大学 大学院都市イノベーション研究院

• HOSODA Akira

  横浜国立大学 大学院都市イノベーション研究院

Bibliographic Information

Other Title

• 若材齢で曲げひび割れが生じたRC梁の収縮特性を考慮した時間依存変形機構の分析

Abstract

 To ensure the required structural performance through the service life, a design method for concrete structures that takes into consideration the influence of material properties should be established. In this research, to clarify the time-dependent deformational behavior of RC beams with flexural cracks generated at early ages, continuous flexural loading of RC beams was conducted, and the effects of shrinkage property, loading age, and environmental condition were experimentally investigated.<br> To understand the time-dependent behavior of RC beams, numerical simulation was performed, using a three-dimensional multi-scale coupled model where the microscopic characteristics of cementitious composites and nonlinear structural mechanics are integrated. This simulation system allows consideration of mechanistic and thermo-hygro induced deformations and the tension stiffening effect after cracking, as well as increases in the diffusivity of water caused by cracking are.<br> The results of this study demonstrated that compressive deformation of concrete due to drying creep causes a significant increase in the tensile stress of reinforcement. Especially under high compressive stress/strength ratio, large creep deformation, which might be due to micro-cracks generated at the ITZ between the cement paste and aggregate, should be properly considered in numerical simulation. Furthermore, deterioration of the bond between compressive reinforcement and the surrounding concrete might be another reason for the large creep deformation.<br> Based on the numerical simulation results (smeared crack model), a new calculation method for flexural crack width was proposed. Comparison of the calculated results and experimental results for total crack width in the equivalent moment zone suggested that concrete between flexural cracks generated at a very early age could deform with less bond deterioration following the deformation of tensile reinforcement. This might be due to the generation of micro-cracks at the ITZ between the cement paste and aggregate, which might prevent internal cracks around reinforcement, thus lessening deterioration of the bond.

Journal

• Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures)

  Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures) 71 (1), 58-71, 2015

  Japan Society of Civil Engineers

Keywords

• shrinkage property
• cracking in early age
• flexural crack width
• creep deformation
• numerical simulation

Details

• CRID: 1390282680332899584
• NII Article ID: 130004962084
• DOI: 10.2208/jscejmcs.71.58
• ISSN: 21856567
• Text Lang: ja
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed