Title:
Torsion Experiment and Cracking-Torque Formulas of Prestressed Concrete Beams
Author(s):
Chyuan-Hwan Jeng and Min Chao
Publication:
Structural Journal
Volume:
115
Issue:
5
Appears on pages(s):
1267-1278
Keywords:
angle of twist; beam; cracking; formula; prestressed concrete; small deformation measurement; softened membrane model; torsion
DOI:
10.14359/51702373
Date:
9/1/2018
Abstract:
Previous torsion experiments on prestressed concrete (PC) beams have various limitations. A new experimental project was therefore conducted to test seven PC beam specimens under pure torsion. This new torsion test of PC beams achieved accurate measurement of small twists before and around cracking, and improved other aspects, including precise measurement of prestressing forces and prestress transfer. The test also enabled assessment of relatively large specimens with medium to high prestress levels and high concrete strengths. Experimental results from seven specimens are presented in this paper. The experimental values of cracking torque Tcr for the seven specimens, and for another 12 specimens from a previous experiment, are compared with the Tcr values calculated using a recently developed rational formula for reinforced concrete. Using these comparisons, a new Tcr formula for PC beams with concentrated or distributed tendons is proposed, which accurately predicts the cracking torques of the 19 specimens.
Related References:
1. Jeng, C.-H., and Hsu, T. T. C., “A Softened Membrane Model for Torsion in Reinforced Concrete Members,” Engineering Structures, V. 31, No. 9, 2009, pp. 1944-1954. doi: 10.1016/j.engstruct.2009.02.038
2. Jeng, C.-H.; Peng, X.; and Wong, Y. L., “Strain Gradient Effect in RC Elements Subjected to Torsion,” Magazine of Concrete Research, V. 63, No. 5, 2011, pp. 343-356. doi: 10.1680/macr.9.00218
3. Jeng, C.-H., “Softened Membrane Model for Torsion in Reinforced Concrete Members,” Advances in Engineering Research, Volume 2, V. M. Petrova, ed., Nova Science Publishers, Inc., Hauppauge, NY, Mar. 2012, pp. 251-338.
4. Jeng, C.-H.; Peng, S.-F.; and Chao, M., “Constitutive Relationships of Concrete for Hollow RC Members in Pure Torsion,” Magazine of Concrete Research, V. 66, No. 17, 2014, pp. 896-912. doi: 10.1680/macr.14.00017
5. Jeng, C.-H., “Unified Softened Membrane Model for Torsion in Hollow and Solid Reinforced Concrete Members: Modeling Precracking and Postcracking Behavior,” Journal of Structural Engineering, ASCE, V. 141, No. 10, 2015, pp. 1-10. doi: 10.1061/(ASCE)ST.1943-541X.0001212
6. Jeng, C.-H., “Simple Rational Formulas for Cracking Torque and Twist of Reinforced Concrete Members,” ACI Structural Journal, V. 107, No. 2, Mar.-Apr. 2010, pp. 189-198.
7. Jeng, C.-H.; Chiu, H.-J.; and Peng, S.-F., “Design Formulas for Cracking Torque and Twist in Hollow Reinforced Concrete Members,” ACI Structural Journal, V. 110, No. 3, May-June 2013, pp. 457-468.
8. Jeng, C.-H., and Chao, M., “Unified Rational Formula for Pre-Cracking Torsional Stiffness of Solid and Hollow Reinforced Concrete Members,” Engineering Structures, V. 99, Apr. 2015, pp. 92-107. doi: 10.1016/j.engstruct.2015.04.038
9. Jeng, C.-H.; Peng, S.-F.; and Chiu, H.-J., “A New Apparatus and Method for Torsion Test of Large-Size Reinforced Concrete Beams,” Journal of Testing and Evaluation, V. 42, No. 1, 2014, pp. 181-195. doi: 10.1520/JTE20120351
10. Jeng, C.-H.; Peng, S.-F.; Chiu, H.-J.; and Hsiao, C.-K., “New Torsion Experiment on Large-Sized Hollow Reinforced Concrete Beams,” ACI Structural Journal, V. 111, No. 6, Nov.-Dec. 2014, pp. 1469-1480. doi: 10.14359/51687166
11. Chao, M., and Jeng, C.-H., “Pre- and Post-Cracking Torsion in Prestressed Concrete Beams: Experimental Study,” Magazine of Concrete Research, V. 69, No. 11, 2017, pp. 555-575. doi: 10.1680/jmacr.16.00349
12. Mukherjee, P. R., “Ultimate Torsional Strength of Plain, Prestressed and Reinforced Concrete Members of Rectangular Cross-Section,” PhD dissertation, West Virginia University, Morgantown, WV, 1967.
13. Chander, H., “Behavior of Prestressed Concrete Rectangular Members Subjected to Pure Torsion,” PhD dissertation, West Virginia University, Morgantown, WV, 1967, 148 pp.
14. Mitchell, D., “The Behaviour of Structural Concrete Beams in Pure Torsion,” PhD thesis, University of Toronto, Toronto, ON, Canada, 1974, 140 pp.
15. McMullen, A. E., and El-Degwy, W. M., “Prestressed Concrete Tests Compared with Torsion Theories,” PCI Journal, V. 30, No. 5, 1985, pp. 96-127. doi: 10.15554/pcij.09011985.96.127
16. Wafa, F. F.; Shihata, S. A.; Ashour, S. A.; and Akhtaruzzaman, A. A., “Prestressed High-Strength Concrete Beams under Torsion,” Journal of Structural Engineering, ASCE, V. 121, No. 9, 1995, pp. 1280-1286. doi: 10.1061/(ASCE)0733-9445(1995)121:9(1280)
17. Fang, I.-K., “The Behavior of High Strength Prestressed Concrete Rectangular Beams Subjected to Pure Torsion, Part II,” Report of Research Project NSC-86-2211-E-006-026, National Science Council, Taiwan, Sept. 1998, 48 pp. (in Chinese)
18. Young, W.-T., “Minimum Torsional Reinforcement in Prestressed High Strength Concrete Beams,” master’s thesis, National Cheng Kung University, Tainan, Taiwan, 1998. (in Chinese)
19. Chiu, H.-J., “Study on the Design Expressions for Minimum Torsion Reinforcement in Structural Concrete Beams,” master’s thesis, National Cheng Kung University, Tainan, Taiwan, 2000, 59 pp. (in Chinese)
20. Chen, G.-H., “A Preliminary Modification of the Softened Membrane Model for Torsion in Prestressed Concrete Members,” master’s thesis, National Chi Nan University, Nantou, Taiwan, June 2012, 92 pp. (in Chinese)
21. Ali, M. A., and White, R. N., “Toward a Rational Approach for Design of Minimum Torsion Reinforcement,” ACI Structural Journal, V. 96, No. 1, Jan.-Feb. 1999, pp. 40-45.
22. Koutchoukali, N., and Belarbi, A., “Torsion of High-Strength Reinforced Concrete Beams and Minimum Reinforcement Requirement,” ACI Structural Journal, V. 98, No. 4, July-Aug. 2001, pp. 462-469.
23. Jeng, C.-H.; Chiu, H.-J.; and Chen, C.-S., “Modeling the Initial Stresses in Prestressed Concrete Members under Torsion,” Structures Congress, Orlando, FL, 2010, pp. 1773-1781. doi: 10.1061/41130(369)162
24. Hsu, T. T. C., and Mo, Y. L., “Softening of Concrete in Torsional Members Prestressed Concrete,” ACI Journal Proceedings, V. 82, No. 5, Sept.-Oct. 1985, pp. 603-615.
25. Sumitro, S.; Jaroševič, A.; and Wang, M. L., “Elasto-magnetic Sensor Utilization on Steel Cable Stress Measurement,” The 1st fib Congress: Concrete Structures in the 21th Century, Osaka, Japan, 2002, pp. 13-19.
26. Chandoga, M.; Fabo, P.; and Jaroševič, A., “Measurement of Forces in the Cable Stays of the Apollo Bridge,” The 2nd fib Congress, 2006, pp. 674-675.
27. Cho, K.; Cho, J.-R.; Kim, S. T.; Park, S. Y.; Kim, Y.-J.; and Park, Y.-H., “Estimation of Prestress Force Distribution in Multi-Strand System of Prestressed Concrete Structures Using Field Data Measured by Electromagnetic Sensors,” Sensors (Basel), V. 16, No. 8, 2016, p. 1317 doi: 10.3390/s16081317
28. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14),” American Concrete Institute, Farmington Hills, MI, 2014, 520 pp.
29. Hsu, T. T. C., and Mo, Y. L., Unified Theory of Concrete Structures, John Wiley & Sons Ltd, West Sussex, UK, 2010, 518 pp.
30. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-11) and Commentary,” American Concrete Institute, Farmington Hills, MI, 2011, 473 pp.
31. Jeng, C.-H., “Explosive Failure Mode of a PC Beam Specimen under Torsion,” https://www.youtube.com/watch?v=Q4eLz11UVaE. (accessed Oct. 2017)
32. Jeng, C.-H., “Torsion Experiment of a PC beam Specimen,” https://www.youtube.com/watch?v=z8_2rw29Rok. (accessed Oct. 2017)
33. Hsu, T. T. C., Torsion of Reinforced Concrete, Van Nostrand Reinhold Co., New York, 1984, 516 pp.