Abstract:

Seismic application of stainless steel rebar (SSR) recently has attracted much attention in the civil engineering due to its superior material properties, including high corrosion resistance and high specific strength. However, as to all new materials, a number of shortcomings are unavoidable, such as high initial costs, unknown low-cycle fatigue behavior and uncertain ductility property.

In this study, a series of tests on selected SSR were carried out. For the purpose of comparison, one type of traditional carbon steel (A706 G60) rebar and a new material (MMFX II) were also tested. A706 G60 has been promoted in the recent design specification of reinforced concrete, particularly in the seismic design. MMFX II is high strength steel appeared in the market recently.

The specific objective of this study is to investigate the low-cycle fatigue and ductility properties of the selected SSR. The test specimens, both for the low fatigue and the monotonic loading conditions, were designed according to the ASTM specifications and fabricated from #8 rebars. The tests were strain controlled. An electronic hydraulic loading system manufactured by MTS at the Structural Engineering & Earthquake Simulation Laboratory (SEESL) at the University at Buffalo was used, and MTS displacement extensometers were used to measure the elongations. For the low-cycle fatigue tests, specimens were subjected to constant amplitude strain of various magnitudes.

Strain based strain-life formulae were obtained by regression analysis of the experimental results. Compared to results of the traditional carbon steel rebar, SSR has shown higher ductility and longer fatigue life.