Title:
Axial Compression Performance of Reinforced Concrete Short Columns with Supplementary V-Shaped Ties
Author(s):
Keun-Hyeok Yang and Won-Woo Kim
Publication:
Structural Journal
Volume:
113
Issue:
6
Appears on pages(s):
1347-1356
Keywords:
axial load; columns; confined concrete; crosstie; ductility ratio; supplementary transverse reinforcement; V-tie
DOI:
10.14359/51689159
Date:
11/1/2016
Abstract:
This paper presents a relatively simple V-shaped tie arrangement approach as an alternative to the conventional crossties for seismic design of reinforced concrete (RC) columns. For easy and quick installation of the individual V-ties, a connector that assembles the V-tie onto a longitudinal bar was also devised. The mechanical contribution of the V-tie was characterized regarding the confining core concrete and preventing the premature buckling of the longitudinal reinforcement. To determine the minimum extension length of V-tie legs into the core concrete, an equivalent lateral force was
derived based on the transverse displacement due to the buckling of longitudinal reinforcing bars. Fourteen columns were tested to failure under concentric axial load to investigate the performance and shortcomings of the proposed V-tie approach. Test results showed that a 90-degree hook of crossties was gradually opened beyond the ultimate strength of columns. In contrast, no V-ties were extracted from core concrete during the period of tests, even for high-strength concrete columns under a compressive strength of 105 MPa (15.2 ksi). As a result, higher ductility ratios were observed in V-tie columns than in crosstie columns. The stressstrain curves of confined concrete obtained from the V-tie columns agreed well with prediction model proposed by Kim et al., indicating that the developed V-tie arrangement effectively confines the core concrete. In summary, the V-ties possess significant potential to provide supplementary transverse reinforcement of RC columns.
Related References:
1. Joint ACI-ASCE Committee 441, “High-Strength Concrete Columns: State of the Art,” ACI Structural Journal, V. 94, No. 5, Sept.-Oct. 1997, pp. 323-335.
2. Sakai, K., and Sheikh, S. A., “What Do We Know about Confinement Reinforced Concrete Columns? A Critical Review of Previous Work and Code Provisions,” ACI Structural Journal, V. 86, No. 2, Mar.-Apr. 1989, pp. 192-207.
3. Bae, S., “Seismic Performance of Full-Scale Reinforced Concrete Columns,” PhD dissertation, University of Texas at Austin, Austin, TX, 2005, 312 pp.
4. Elwood, K. J.; Maffel, J.; Riederer, K. A.; and Telleen, A. K., “Improving Column Confinement—Part 1: Assessment of Design Provisions,” Concrete International, V. 31, No. 11, Nov. 2009, pp. 32-39.
5. Hong, K. N.; Akiyama, M.; Yi, S. T.; and Suzuki, Y. M., “Stress-Strain Behaviour of High-Strength Concrete Columns Confined by Low Volumetric Ratio Rectangular Ties,” Magazine of Concrete Research, V. 58, No. 2, 2006, pp. 101-115. doi: 10.1680/macr.2006.58.2.101
6. Razvi, S. R., and Saatcioglu, M., “Confinement Model for High Strength Concrete,” Journal of Structural Engineering, ASCE, V. 125, No. 3, 1999, pp. 281-289. doi: 10.1061/(ASCE)0733-9445(1999)125:3(281)
7. Watson, S.; Zahn, F. A.; and Park, R., “Confining Reinforcement for Concrete Columns,” Journal of Structural Engineering, ASCE, V. 120, No. 6, 1994, pp. 1798-1824. doi: 10.1061/(ASCE)0733-9445(1994)120:6(1798)
8. Park, R., “Ductile Design Approach for Reinforced Concrete Frames,” Earthquake Spectra, V. 2, No. 3, 1986, pp. 565-619. doi: 10.1193/1.1585398
9. Sakino, K., and Sun, Y., “Stress-Strain Curve of Concrete Confined by Rectilinear Hoop,” Journal of Structure and Construction Engineering, V. 461, 1994, pp. 95-104.
10. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14),” American Concrete Institute, Farmington Hills, MI, 2014, 519 pp.
11. Sheikh, S. A., and Uzumeri, S. M., “Analytical Model for Concrete Confinement in Tied Columns,” Journal of Structural Engineering, ASCE, V. 108, 1982, pp. 2703-2722.
12. Ozcebe, G., and Saatcioglu, M., “Confinement of Concrete Columns for Seismic Loading,” ACI Structural Journal, V. 84, No. 4, July-Aug. 1987, pp. 308-315.
13. Mander, J. B.; Priestley, M. J. N.; and Park, R., “Observed Stress-Strain Behavior of Confined Concrete,” Journal of Structural Engineering, ASCE, V. 114, No. 8, 1988, pp. 1827-1849. doi: 10.1061/(ASCE)0733-9445(1988)114:8(1827)
14. Saatcioglu, M., and Razvi, S. R., “Strength and Ductility of Confined Concrete,” Journal of Structural Engineering, ASCE, V. 118, No. 6, 1992, pp. 1590-1607. doi: 10.1061/(ASCE)0733-9445(1992)118:6(1590)
15. Fafitis, A., and Shah, S. P., “Predictions of Ultimate Behavior of Confined Columns Subjected to Large Deformations,” ACI Structural Journal, V. 82, No. 4, July-Aug. 1985, pp. 423-433.
16. Muguruma, H.; Nishiyama, M.; Watanabe, F.; and Tanaka, H., “Ductile Behavior of High-Strength Concrete Columns Confined by High-Strength Transverse Reinforcement,” Evaluation and Rehabilitation of Concrete Structures and Innovations in Design, SP-128, V. M. Malhotra, ed., American Concrete Institute, Farmington Hills, MI, 1991, pp. 877-891.
17. Lukkunaprasit, P., and Sittipunt, C., “Ductility Enhancement of Moderately Confined Concrete Tied Columns with Hook-Clips,” ACI Structural Journal, V. 100, No. 4, July-Aug. 2003, pp. 422-429.
18. Kim, W. W., and Yang, K. H., “Effect of Bending Angle and Embedment Length on the Bond Characteristics of V-Shaped Tie Reinforcement,” Journal of the Korea Institute of Building Construction, 2015. (in Korean)
19. Kim, W. W.; Mun, J. H.; and Yang, K. H., “Simplified Model for the Stress-Strain Relationship of Confined Concrete,” Journal of the Architectural Institute of Korea: Structure & Construction, V. 31, No. 4, 2015, pp. 79-86. (in Korean)
20. Chen, W. F., and Lui, E. M., Structural Stability: Theory and Implementation, Elsevier, New York, 1987, 490 pp.
21. Chung, H. S.; Yang, K. H.; Lee, Y. H.; and Eun, H. C., “Strength and Ductility of Laterally Confined Concrete Columns,” Canadian Journal of Civil Engineering, V. 29, No. 6, 2002, pp. 820-830. doi: 10.1139/l02-084
22. Kent, D. C., and Park, R., “Flexural Members with Confined Concrete,” Journal of the Structural Division, ASCE, V. 97, 1971, pp. 1969-1990.