Transient State Tensile Test Results of Structural Steels S235, S355 and S350GD+Zat Elevated Temperatures

摘要

The Laboratory of Steel Structures at the Helsinki University of Technology haspublished several research reports consisting of transient state tensile test results of different structural steel materials. Transient state tensile test method was used to examine the mechanical properties of hot-rolled structural steels S235 (Fe360B) and S355 (RAEX 37-52) and cold-formed structural steel sheets S320GD+Z(Z32) and S350GD+Z(Z35) at elevated temperatures. All the studies were carried out with using the same testing method except in the study of structural steel S320GD+Z. Because in this study testing facilities were different the test results of S320GD+Z are not directly comparable with the other test results. Transient state tensile test data was used to determine the temperature-strain and stress-strain relationships and mechanical properties for the structural steels at temperatures 20 to 700C. Furthermore steady state tensile tests were carried out for the test materials to compare the difference of the test results when using different testing methods. The creeping phenomenon during transient state tensile tests affects the test results so that the steady state stress-strain curves are higher than the transient state test curves especially when a high rate of loading is used. The rate of loading in steady state tests has a substantial effect on test results. Results of these studies are compared with the values of mechanical properties given in Eurocode 3, in the European Recommendations for the Fire Safety of Steel Structures and in the Finnish Code of Steel Structures.