Title:
Effect of Low Reinforcement Ratio on Reinforced Concrete Wall with 700 MPa Reinforcing Bars
Author(s):
Sung-Hyun Kim and Hong-Gun Park
Publication:
Structural Journal
Volume:
120
Issue:
2
Appears on pages(s):
171-189
Keywords:
cyclic loading; Grade 700 MPa (101.5 ksi) bar; minimum reinforcement ratio; shear strength; shear wall
DOI:
10.14359/51737142
Date:
1/1/2023
Abstract:
High-strength reinforcing bars can be used for the economical
design of reinforced concrete shear walls by reducing the reinforcement ratio. However, current design codes require the minimum reinforcement ratio regardless of the yield strength of reinforcing bars. In this study, to investigate the adequacy of the minimum reinforcement ratio of Grade 700 MPa (101.5 ksi) reinforcing bars, seven wall specimens were tested under cyclic lateral loading. The test parameters were the failure mode (shear or flexural mode), reinforcing bar yield strength (Grade 400 and 700 MPa [58 and 101.5 ksi]), and reduced minimum reinforcement ratio (ρv = 0.14 to 0.27% and ρh = 0.14 to 0.25%). The test results showed that the peak strengths of walls with 700 MPa (101.5 ksi) reinforcement
were greater than the nominal flexural and shear strengths,
even with a lower minimum reinforcement ratio (ρv = 0.14% and ρh = 0.14%). However, the safety margin and ductility decreased with increasing flexural and shear crack widths. Additionally, the strengthening of existing walls (Grade 400 reinforcing bars) with high-strength reinforcing bars (Grade 700) was studied. The test results showed that the shear contribution of extended wall segments with Grade 700 reinforcing bars was limited by the early yielding of Grade 400 reinforcing bars.
Related References:
1. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318R-19) (Reapproved 2022),” American Concrete Institute, Farmington Hills, MI, 2019, 624 pp.
2. ACI Committee 349, “Code Requirements for Nuclear Safety-Related Concrete Structures (ACI 349-13) and Commentary,” American Concrete Institute, Farmington Hills, MI, 2014, 196 pp.
3. EN 1992-1-1:2004, “Eurocode 2: Design of Concrete Structures – Part 1-1: General Rules and Rules for Buildings,” European Committee for Standardization, Brussels, Belgium, 2004, 227 pp.
4. EN 1998, “Eurocode 8: Design of Structures for Earthquake Resistance,” European Committee for Standardization, Brussels, Belgium, 2004.
5. Cheng, M.-Y.; Hung, S.-C.; Lequesne, R. D.; and Lepage, A., “Earthquake-Resistant Squat Walls Reinforced with High-Strength Steel,” ACI Structural Journal, V. 113, No. 5, Sept.-Oct. 2016, pp. 1065-1076. doi: 10.14359/51688825
6. Huq, M. S.; Weber-Kamin, A. S.; Ameen, S.; Lequesne, R. D.; and Lepage, A., “High-Strength Steel Bars in Earthquake-Resistant T-Shaped Concrete Walls,” SM Report No. 128, The University of Kansas Center for Research, Inc., Lawrence, KS, 2018, 398 pp.
7. Kim, S.-H., and Park, H.-G., “Shear Strength of Reinforced Concrete Wall with 700 MPa Shear Reinforcement,” ACI Structural Journal, V. 118, No. 2, Mar. 2021, pp. 167-181.
8. Cardenas, A. E.; Russell, H. G.; and Corley, W. G., “Strength of Low-Rise Structural Walls,” Reinforced Concrete Structures Subjected to Wind and Earthquake Forces, SP-63, American Concrete Institute, Farmington Hills, MI, 1980, pp. 221-242.
9. Hidalgo, P. A.; Ledezma, C. A.; and Jordan, R. M., “Seismic Behavior of Squat Reinforced Concrete Shear Walls,” Earthquake Spectra, V. 18, No. 2, May 2002, pp. 287-308. doi: 10.1193/1.1490353
10. Carrillo, J., and Alcocer, S. M., “Shear Strength of Reinforced Concrete Walls for Seismic Design of Low-Rise Housing,” ACI Structural Journal, V. 110, No. 3, May-June 2013, pp. 415-426.
11. Baek, J.-W.; Park, H.-G.; Choi, K.-K.; Seo, M.-S.; and Chung, L., “Minimum Shear Reinforcement of Slender Walls with Grade 500 MPa (72.5 ksi) Reinforcing Bars,” ACI Structural Journal, V. 115, No. 3, May 2018, pp. 761-774. doi: 10.14359/51701281
12. Puranam, A. Y., and Pujol, S., “Reinforcement Limits for Reinforced Concrete Elements with High-Strength Steel,” ACI Structural Journal, V. 116, No. 5, Sept. 2019, pp. 201-212. doi: 10.14359/51716762
13. Hawkins, N. M., and Ghosh, S. K., “Acceptance Criteria for Special Precast Concrete Structural Walls Based on Validation Testing,” PCI Journal, V. 49, No. 5, Sept.-Oct. 2004, pp. 78-92. doi: 10.15554/pcij.09012004.78.92
14. Park, R., “State-of-the-Art Report: Ductility Evaluation from Laboratory and Analytical Testing,” Proceedings, Ninth World Conference on Earthquake Engineering, Tokyo-Kyoto, Japan, Aug. 1988, 12 pp.
15. Park, H.-G.; Baek, J.-W.; Lee, J.-H.; and Shin, H.-M., “Cyclic Loading Tests for Shear Strength of Low-Rise Reinforced Concrete Walls with Grade 550 MPa Bars,” ACI Structural Journal, V. 112, No. 3, May-June 2015, pp. 299-310. doi: 10.14359/51687406
16. Baek, J.-W.; Park, H.-G.; Shin, H.-M.; and Yim, S.-J., “Cyclic Loading Test for Reinforced Concrete Walls (Aspect Ratio 2.0) with Grade 550 MPa (80 ksi) Shear Reinforcing Bars,” ACI Structural Journal, V. 114, No. 3, May-June 2017, pp. 673-686. doi: 10.14359/51689437
17. Baek, J.-W.; Park, H.-G.; Lee, J.-H.; and Bang, C.-J., “Cyclic Loading Test for Walls of Aspect Ratio 1.0 and 0.5 with Grade 550 MPa (80 ksi) Shear Reinforcing Bars,” ACI Structural Journal, V. 114, No. 4, July-Aug. 2017, pp. 969-982. doi: 10.14359/51689680