ABSTRACT
Abstract AFRP elements used for structural concrete applications are unidirectional fiber composites mostly in the shape of round bars. In practical use, they will axially stressed in tension. Experiments showed that the long-term static stresses may reduce the short-term tensile strength of FRP, especially if a hostile environment damaging the fibers is simultaneously present. The strength reduction depends primarily on two factors. The first factor is the magnitude of the long-term stress, the higher the latter the greater the reduction will be. The environment is the second factor. Permanent contact of the AFRP element with an alkaline solution - chemically similar to the concrete's pore water - will definitely damage the fibers. For the application of AFRP bars for pre-tensioned concrete elements the stress-rupture behaviour of AFRP when subjected to the surrounding concrete environment and also to other external and hostile environmental conditions must be known (drying, wetting, temperature, de-icing salt, solutions etc.). This report deals with the stress-rupture behaviour of FRP tensile elements under static load and several environmental conditions and temperatures simulating the real conditions during service life. Keywords: AFRP, hostile environments, stress-rupture, temperature
1 Introduction
Within the framework of a European research project mechanical properties of FRP have been investigated. The stress-rupture behaviour of AFRP bars under various environments was of special interest for the prediction of endurance time of tensile elements used for pre-tensioned concrete elements. The experiments were performed with AFRP round bars (Arapree 200.000) with a fiber volume of 56 %, made from Aramid fibers Twaron EM. The mechanical short-term properties were determined in preceding tests, reported in [1] and [2], Table 1.
