Characteristics, Mechanism And Factors Of Fatigue Failure Of Steel Structure Steel

In steel structure building, steel is the main factor that determines the performance of steel structure. The steel structure has good performance and is widely used in steel structure workshop buildings and color steel plate activity room buildings. But any kind of material can be problematic. In steel structure buildings, fatigue failure of steel is a frequent problem. The following introduces the fatigue failure characteristics and mechanism of steel structure steel.
Under the action of cyclic load (continuous anti-load), the steel of the steel structure undergoes infinite cycles, and the steel is damaged, which is called fatigue. Fatigue failure is the result of accumulated damage, which is caused by the stress concentration caused by defects in the steel, and the microscopic cracks continue to develop under cyclic loading, forming macroscopic cracks and causing steel fractures. The fatigue failure of steel belongs to brittle failure, and the average cross-sectional stress during failure is less than the yield strength of steel.
The fatigue failure process of steel structure steel goes through three stages: the formation of cracks, the slow propagation of cracks and rapid fracture after that. Under repeated loading, there will always be stress concentration in the weak place of the internal quality of the steel, plastic cross-shape appears at individual points, and hardened and gradually formed some microscopic cracks, and then the number of cracks increases and connects with each other to develop into macroscopic cracks, the effective cross-sectional area decreases, the stress concentration phenomenon becomes more and more serious, the cracks continue to expand, when the steel section is weakened to insufficient to resist the external load, the steel suddenly breaks. Therefore, the fatigue damage, plastic deformation is extremely small, and there is no obvious warning of damage.
The fatigue strength of steel structure steel is mainly related to the internal defects, stress concentration, residual stress, stress cycle times and stress amplitude of components and connections. The fatigue performance of welded steel structures is mainly related to the stress amplitude, while the fatigue performance of non-welded steel structures is related to the large stress, stress ratio and lack of cycle number gate effect.