Self-Post-Tensioned Concrete Elements Using Shape Memory Alloys

Shape memory alloys (SMAs) are a class of smart materials that recover apparent plastic deformation (~6-8% strain) after heating, thus “remembering” the original shape. This shape memory effect (SME) can be exploited for self post-tensioning applications. NiTi-based SMAs are promising due to their corrosion resistance and resistance against low frequency/cycle fatigue failure. This study investigates self-post-tensioned (SPT) concrete elements by activating the SME of NiTiNb, a class of wide-hysteresis SMAs, using the heat of hydration of grout. Both NiTiNb and activation via hydration heat have yet to be explored for prestressing of concrete using SMAs. First, the localized strain fields during the tensile stress-induced martensitic transformation in NiTiNb wide-hysteresis shape memory alloys are studied, and the material design and characterization of the SMA tendons are discussed. Then, the temperature increase due to the heat of hydration of four commercially available grouts is investigated. Pull-out tests are conducted to investigate the bond between the grout and SMA bar. The use of self post- tensioned SMA tendons in concrete elements will increase overall sustainability of bridge structures by (i) minimizing the susceptibility of post-tensioning tendons to corrosion; (ii) enabling the adjustment of prestressing force during service life; and (iii) simplifying the tendon installation.

• Supplemental Notes:
  • This paper was sponsored by TRB committee AFF30 Concrete Bridges.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Ozbulut, Osman E
  • Sherif, Muhammad
  • Hamilton, Reginald H
• Conference:
  • Transportation Research Board 94th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2015-1-11 to 2015-1-15
• Date: 2015

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; Photos; References; Tables;
• Pagination: 15p
• Monograph Title: TRB 94th Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Bridge construction; Concrete bridges; Girders; Grout; Heat of hydration; Posttensioning; Smart materials; Tendons (Materials)
• Uncontrolled Terms: Shape memory alloys
• Subject Areas: Bridges and other structures; Construction; Highways; Materials; I30: Materials; I53: Construction of Bridges and Retaining Walls;

Filing Info

• Accession Number: 01555663
• Record Type: Publication
• Report/Paper Numbers: 15-4512
• Files: TRIS, TRB, ATRI
• Created Date: Feb 27 2015 10:05AM