Abstract

The study deals with the use of shape memory alloys (SMAs) to create prestress states in concrete prismatic beams. Nickeltitanium SMA wires with suitable transformation temperatures are used to this purpose. The wires are first stretched in a martensitic state at ambient temperature. Then they are placed onto the surface of the beams. A thermal cycle is applied to transform the martensite to austenite, in order to activate the shape memory effect in the wires. The strain evolution in the concrete beams is measured with strain gauges. A prestress effect is clearly observed in the beams during the procedure until cooling down to ambient temperature. The influence of the initial stretch of the wires and the transformation temperatures is discussed.

KEYWORDS

shape-memory alloy, nickel-titanium, concrete, prestress.