Shrinkage Stress Analysis of Concrete Slab in Multi-Story Building Considering Construction Sequence

- Journal title : Journal of the Korea Concrete Institute
- Volume 13, Issue 5, 2001, pp.457-465
- Publisher : Korea Concrete Institute
- DOI : 10.22636/JKCI.2001.13.5.457

Title & Authors

Shrinkage Stress Analysis of Concrete Slab in Multi-Story Building Considering Construction Sequence

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Abstract

Shrinkage strains of concrete slab in multi-story building are restrained by structural members such as columns or walls, then can induce cracks due to excessive shrinkage stress over tensile strength of member. In this study, a shrinkage stress analysis method of concrete slab in multi-story building considering not only material properties such as shrinkage, creep and reinforcement effect but also construction sequence is proposed. Tensile stresses of slab due to shrinkage are calculated by converting shrinkage strains into equivalent temperature gradients, creep that can release shrinkage stress can be considered by replacing the modulus of elasticity of concrete, Ec , to the effective secant modulus of elasticity of concrete, Eeff/ Reinforcements are also considered by modeling them as equivalent beam elements in FEM program. Results of step by step analysis reflecting construction sequence summed up to calculate stresses of the whole building considering that shrinkage stresses of the building come from the difference of shrinkage between i-th floor and (i-1)-th floor, named as effecitive shrinkage, and it can be varied by construction sequence. The results of 10-story example building show that shrinkage stresses of lower floors are greater than those of upper floors, that is, stresses of lower floors(1∼2FI.) exceed modulus of rupture of concrete, but stress ratios of higher floors are in the range of 27.9∼92.8%.

Keywords

equivalent temperature gradient;effecitve secant modulus of elasticity;effective shrinkage;shrinkage analysis;step by step analysis;

Language

Korean

Cited by

References

1.

Journal of Engineering Mechanics, 1998.
pp.765-774

2.

ACI Struct. Journal, 1988.
vol.85. 45,
pp.395-404

3.

Mat. and Struct., 0000.
vol.27. 170,
pp.324-440

4.

Handbook of Concrete Engineering(2nd Edition), 0000.
pp.121-138

5.

ACI 224R-90, 1990.

6.

96STR06, 1998.
pp.7

7.

한국전산구조공학회 2000년 봄 학술발표회 논문집, 2000.
vol.13. 1,
pp.238-245

8.

ACI 209R-92, 1997.

9.

철근콘크리트 구조설계, 1996.
pp.21

10.

Reinforced Concrete Structure, 1975.
pp.427-460

11.

Engineering Bulletin No. EB108D, 1987.
pp.6-7

12.

ACI 224.2R-92, 1997.