Title:
Experiments on Continuous Unbonded Post-Tensioned Beams with 2400 MPa (350 ksi) Strands
Author(s):
Kyungmin Kim and Thomas H.-K. Kang
Publication:
Structural Journal
Volume:
116
Issue:
5
Appears on pages(s):
125-136
Keywords:
DOI:
10.14359/51716758
Date:
9/1/2019
Abstract:
Experiments on seven two-span unbonded post-tensioned beams were conducted under four-point static loading conditions. Variables considered included: strand type (nominal tensile strength); tendon drape (height of tendon profile); and magnitude of prestress. Experimental emphasis was placed on the applicability of using higher-strength 2400 MPa (350 ksi) strands instead of ordinary 1860 MPa (270 ksi) strands in unbonded post-tensioned beam members. Observed results revealed that specimens with 2400 MPa (350 ksi) tensile strength 15.2 mm (0.6 in.) diameter strands developed equivalent tendon stress increment, load-carrying capacity, and flexural ductility while at the ultimate limit state having earlier and wider plastic hinge.
Related References:
AASHTO, 2017, “AASHTO LRFD Bridge Design Specifications,” eighth edition, American Association of State Highway Transportation Officials, Washington, DC.
Abo Alarab, L. A.; Poursaee, A.; and Ross, B. E., 2019, “An Experimental Method for Evaluating Reinforcement Corrosion in Cracked Concrete,” Journal of Structural Integrity and Maintenance, V. 4, No. 1, pp. 43-50. doi: 10.1080/24705314.2019.1565058
ACI Committee 318, 2014, “Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary,” American Concrete Institute, Farmington Hills, MI, 520 pp.
ACI Committee 423, 2016, “Guide to Estimating Prestress Loss (ACI 423.10R-16),” American Concrete Institute, Farmington Hills, MI, 64 pp.
Au, F. T. K., and Du, J. S., 2004, “Prediction of Ultimate Stress in Unbonded Prestressed Tendons,” Magazine of Concrete Research, V. 56, No. 1, pp. 1-11. doi: 10.1680/macr.2004.56.1.1
Burns, N. H.; Charney, F. A.; and Vines, W. R., 1978, “Tests of One-Way Post-Tensioned Slabs with Unbonded Tendons,” PCI Journal, V. 23, No. 5, pp. 66-83. doi: 10.15554/pcij.09011978.66.83
Burns, N. H.; Helwig, T.; and Tsujimoto, T., 1991, “Effective Prestress Force in Continuous Post-Tensioned Beams with Unbonded Tendons,” ACI Structural Journal, V. 88, No. 1, Jan.-Feb., pp. 84-90.
Harajli, M.; Mabsout, M. E.; and Al-Hajj, J. A., 2002, “Response of Externally Post-tensioned Continuous Member,” ACI Structural Journal, V. 99, No. 5, Sept.-Oct., pp. 671-680.
Harajli, M. H., 2006, “On the Stress in Unbonded Tendons at Ultimate: Critical Assessment and Proposed Changes,” ACI Structural Journal, V. 103, No. 6, Nov.-Dec., pp. 803-812.
Harajli, M. H., 2012, “Tendon Stress at Ultimate in Continuous Unbonded Post-Tensioned Members: Proposed Modification of ACI 318, Eq. (18-4) and (18-5),” ACI Structural Journal, V. 100, No. 2, Mar.-Apr., pp. 183-192.
Harajli, M. H., and Hijazi, S. A., 1991, “Evaluation of the Ultimate Steel Stress in Partially Prestressed Concrete Members,” PCI Journal, V. 36, No. 1, pp. 62-82. doi: 10.15554/pcij.01011991.62.82
KCI, 2012, “Concrete Structure’s Code (KCI-12),” Korea Concrete Institute, Seoul, Korea. (in Korean)
Kim, K., and Kang, T. H.-K., 2018, “Monitoring Secondary Moment of Continuous Unbonded Post-Tensioned Concrete Beams,” PTI Journal, V. 14, No. 2, Dec., pp. 5-16.
Kim, J.; Seong, T.; and Lee, J., 2012, “Development of 2,160 MPa/2,400 MPa PS Strand and Its Application Technology,” Magazine of the Korea Concrete Institute, V. 24, No. 3, pp. 45-50. (in Korean)
Kim, J. K.; Kim, J.; and Kwon, S. H., 2014, “Mechanical Properties of a New Prestressing Strand with Ultimate Strength of 2160 MPa,” KSCE Journal of Civil Engineering, V. 18, No. 2, pp. 607-615. doi: 10.1007/s12205-014-0065-6
Kim, J. K.; Seong, T. R.; Jang, K. P.; and Kwon, S. H., 2013, “Tensile Behavior of New 2,200 MPa and 2,400 MPa Strands according to Various Types of Mono Anchorage,” Structural Engineering and Mechanics, V. 47, No. 3, pp. 383-399. doi: 10.12989/sem.2013.47.3.383
Kim, J. K.; Yang, J. M.; and Yim, H. J., 2016, “Experimental Evaluation of Transfer Length in Pretensioned Concrete Beams Using 2,400-MPa Prestressed Strands,” Journal of Structural Engineering, ASCE, V. 142, No. 11, p. 04016088 doi: 10.1061/(ASCE)ST.1943-541X.0001567
Kordina, K., and Hegger, J., 1987, “Determination of the Ultimate Strength in Bending in the Case of Prestressing without Bond,” Beton- und Stahlbetonbau, V. 84, No. 4, pp. 85-90. (in German) doi: 10.1002/best.198700150
KS D 7002, 2011, “Uncoated Stress-Relieved Steel Wires and Strands for Prestressed Concrete,” Korea Agency for Technology and Standards, Seoul, Korea.
Lee, S.-H.; Shin, K.-J.; and Kang, T. H.-K., 2015, “Flexural Strengthening of Continuous Concrete Beams Using Externally Prestressed Steel Bars,” PCI Journal, V. 60, No. 1, pp. 68-86.
Maguire, M.; Collins, W. N.; Halbe, K. R.; and Roberts-Wollmann, C. L., 2016, “Multi-Span Members with Unbonded Tendons: Ultimate Strength Behavior,” ACI Structural Journal, V. 113, No. 2, Mar.-Apr., pp. 195-204.
Naaman, A. E.; Burns, N.; French, C.; Gamble, W. L.; and Mattock, A. H., 2002, “Stresses in Unbonded Prestressing Tendons at Ultimate: Recommendation,” ACI Structural Journal, V. 99, No. 4, July-Aug., pp. 518-529.
Pannell, F. N., 1969, “The Ultimate Moment of Resistance of Unbonded Prestressed Concrete Beams,” Magazine of Concrete Research, V. 21, No. 66, pp. 43-54. doi: 10.1680/macr.1969.21.66.43
Park, H., and Cho, J.-Y., 2017, “Ductility Analysis of Prestressed Concrete Members with High-Strength Strands and Code Implications,” ACI Structural Journal, V. 114, No. 2, Mar.-Apr., pp. 407-416. doi: 10.14359/51689435
PTI, 2000, “PTI M50.2-00: Anchorage Zone Design,” Post-Tensioning Institute, Farmington Hills, MI.
Song, L.; Fan, Z.; and Hou, J., 2019, “Experimental and Analytical Investigation of the Fatigue Flexural Behavior of Corroded Reinforced Concrete Beams,” International Journal of Concrete Structures and Materials, V. 13.
Tam, A., and Pannell, F. N., 1976, “Ultimate Moment of Resistance of Unbonded Partially Prestressed Reinforced Concrete Beams,” Magazine of Concrete Research, V. 28, No. 97, pp. 203-208. doi: 10.1680/macr.1976.28.97.203
Yang, J. M.; Kim, J.; and Yoo, D., 2018, “Transfer Length in Full-Scale Pretensioned Concrete Beams with 1.4 m and 2.4 m Section Depths,” Engineering Structures, V. 171, pp. 433-444. doi: 10.1016/j.engstruct.2018.05.104
Yang, K.-H., and Kang, T. H.-K., 2011, “Equivalent Strain Distribution Factor for Unbonded Tendon Stress at Ultimate,” ACI Structural Journal, V. 108, No. 2, Mar.-Apr., pp. 217-226.