Abstract
Through the static tensile test of Q690 high-strength steel, the relevant mechanical parameters are obtained and the maximum fatigue load is determined. The fatigue life is measured by the fatigue test under the load. According to the fatigue cumulative damage method, the number of fatigue pre-damage vibration is designed in proportion. Then the fatigue pre-damage test is carried out on the high-strength steel, the stress-strain curve and the variation of residual mechanical property reduction coefficient with fatigue damage were drawn. The results show that: compared with the undamaged specimens, the yield strength and tensile strength of Q690 steel are less affected by fatigue damage, but the elongation changes more significantly, and the elastic modulus is not significantly affected. Finally, through the change of mechanical properties of Q690 high-strength steel with different fatigue damage, it provides a scientific basis for the performance evaluation of existing Q690 high-strength steel structure after fatigue damage.
Highlights
High-strength steel refers to structural steel with a yield strength of ≥460 MPa
The results show that: compared with the undamaged specimens, the yield strength and tensile strength of Q690 steel are less affected by fatigue damage, but the elongation changes more significantly, and the elastic modulus is not significantly affected
It can be seen from the figure that the Q690 high-strength steel specimens have no obvious yield plateau after fatigue damage, so the yield strength value is taken as the stress value corresponding to 0.2% residual deformation; The increase of fatigue times makes the fatigue damage aggravate, and the ultimate strength of the specimens gradually decreases, and the strain difference in the strengthening stage increases with the increase of the number of vibrations, and reaches the maximum value at 45,000 times; the strain of the Q690 high-strength steel after fatigue damage has been reduced to varying degrees
Summary
High-strength steel refers to structural steel with a yield strength of ≥460 MPa. Compared with ordinary steel, high-strength steel has great differences in material properties and chemical composition [1]. High-strength steel is used extremely frequently in the construction industry, automobile production, bridge construction, transmission tower structures, etc These components will be subjected to continuous random alternating loads such as wind load, wave load, vehicle load, crane load and crowd load for a long time during the service period, and fatigue is the process of local damage to the structure under the load, and the cumulative damage will cause Cracks to occur in components, and fatigue failure occurs when the actual stress on the structure is greater than its own resistance [4]. In various structural failure cases, fatigue damage accounts for 50% to 90% [5], causing huge economic losses and casualties to society
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