Experimental approach to strength reduction and elongation of self‐tempered reinforcing bars tensioned at a steady and an increasing temperature

Abstract

This paper describes experiments performed on specimens of reinforcing bars 10, 12, and 16 mm in diameter. The bars were made of 500 MPa steel produced with Tempcore technology and were subject to simultaneous action of high temperature and tension. The experiments were performed both at a constant temperature of 100, 200, 300, 400, 500, and 600°C and in an increasing temperature and constant load corresponding to 0, 30, 45, 60, or 75% of steel yield strength at a room temperature. The analysis of the obtained results is focused on the reduction of steel strength and on the bar elongation due to high temperature. In the former case, different failure criteria were considered, which corresponded to the elongation of 0.2%, the elongation of 2% or the bar failure. The experimental results were compared with Eurocode 1992‐1‐2 models for the bar elongation below and over 2% and against results of similar test reported in the literature. In the study of bar elongation, different components of total elongation, which can be measured during a constant and an increasing temperature test, are described and compared with each other and Eurocode 1992‐1‐2 model.