The National Academies

NCHRP IDEA 20-30/IDEA 210 [Active (IDEA)]

Material Characteristics of Cu-Based Superelastic Alloys for Applications in Bridge Columns to Improve Seismic Performance

  Project Data
Funds: $130,000
Staff Responsibility: Inam Jawed
Research Agency: University of Southern California
Principal Investigator: Bora Gencturk
Fiscal Year: 2018

This project is exploring the use of Cu-Al-Mn (CAM) superelastic alloys (SEAs) in bridge columns to improve seismic performance through a rigorous evaluation of their material characteristics. Work in Stage 1 of the project involves assessing the mechanical properties and corrosion resistance of CAM SEAs. Low-cycle fatigue tests with a 5% cyclic tensile strain amplitude on both single crystal and polycrystalline CAM SEAs of 20 mm diameter will be performed at -40°C, 25°C and 50°C. Corrosion characteristics of 20 mm CAM SEAs in a 1 M NaCl solution will be measured through cyclic polarization testing. The results will be used to derive the open corrosion, pitting and protection potentials and Tafel slopes to determine the corrosion rates. Following this, the effect of long term corrosion on mechanical properties of CAM SEA bars will be measured and a cyclic tensile test will be conducted on corroded specimens to determine changes in the mechanical properties. Various mechanical bar splices to join a 20 mm CAM SEA bar with a 22 mm (#7) steel rebar will be tested to identify those that show satisfactory performance. The machinability index of CAM SEAs will be determined using both tool life method and abrasion production rate. A quantitative cost estimation of both single crystal and poly crystalline CAM SEAs will be made and compared with those of the NiTi SEAs. In this estimation, the cost of raw materials (based on the alloy percentages), the costs associated with the fabrication process, and the cost of amount of materials (both concrete and reinforcement) needed in a bridge column designed to the same strength will be accounted for. A draft final report will be prepared providing all relevant data, findings, and conclusions along with recommendations on how to use the CAM SEAs in bridges.

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