01005385

Monograph

http://onlinepubs.trb.org...y/NCHRP91_Final_Report.pdf

This Innovations Deserving Exploratory Analysis (IDEA) project focused on the application of shape memory alloy (SMA) restrainers to improve the resistance of highway bridges to seismic damage. Work in the initial stage involved developing cost effective and mechanically stable SMAs for bridge rehabilitation that included ternary alloys of Ni and Ti doped with Fe or Cr. The results show that the binary form of SMAs (NiTi) exhibited superior performance as compared with the ternary NiTiCr or NiTiFe alloys. Work was performed on optimizing the performance of SMAs via thermo-mechanical processing. The effect of temperature on the superelastic cyclic properties of selected alloys was also evaluated in order to establish the temperature range for optimum performance. Work in the final stage involved fabricating and testing SMA-based prototype restrainers for use on bridges in dynamic laboratory and shake table tests. The SMA restrainers were found to be superior to steel restrainers in limiting relative hinge displacements, with maximum hinge displacement being about half of steel restrainers. They also showed minimal residual strain after repeated cycling and, unlike steel, could undergo many loading cycles with little degradation of properties. With equivalent restrainers under identical earthquake motion, the SMA restrainers produced lower block acceleration as compared to steel restrainers and reached only their yield level while the steel restrainers failed. Full-scale tests on bridges are needed to demonstrate the applicability of the technology in the field.

This NCHRP-IDEA investigation was conducted by the Georgia Institute of Technology, Atlanta. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

NCHRP IDEA Project 91

English

44p

2005-8

NCHRP-IDEA Program Project Final Report

Final Report

Print

Figures (35) ; Photos (7) ; Tables (8)

Bridges; Earthquake resistant design; Highway bridges; Iron alloys; Laboratory tests; Nickel alloys; Optimization; Performance; Prototypes; Rehabilitation; Technological innovations; Temperature; Titanium alloys

Innovations Deserving Exploratory Analysis (IDEA) (Program)

Chromium alloys; Displacements (Structural); Residual strain; Restrainers (Bridges); Shape memory alloys

Bridges and other structures; Design; Geotechnology; Highways; Materials; I24: Design of Bridges and Retaining Walls; I34: Steels and Metals

TRIS, TRB

Oct 14 2005 8:58AM