Fatigue Life Of The Reinforced Concrete Platform Bearing Power Machines

With the modernization development in China, a large number of power equipmentsneed to be located in the plant platforms, while the repeated loads which is generated bythe equipment operation are easily cause the fatigue damage of the platforms. Fatigue lifeprediction of the platform building should be paid more attention, while the currentanalysis of fatigue life can not be well applied to fatigue life prediction of the platform.Whereby,6.8m platform of sintering engineering sinter screening room in the Baotou steelgroup co., LTD was selected as the investigation object with the different typical workingconditions of the single vibrating screen opening, two vibrating screen opening and threevibrating screen opening. The works this paper presented are as follows:Natural frequency and acceleration amplitude of the platform were actual measured,natural vibration characteristics were presented in the closing and opening of vibratingscreen, respectively. The target platform finite element model was built by ANSYS, andthe natural frequency and first six order vibration modes of the platform was presented bythe modal analysis. Meanwhile, when the vibrating screen was opened, the accelerationamplitude and response frequency was presented. Compared the simulation results withactual measured results, it is demonstrated that the rationality of the finite element modelon the fatigue analysis can be proved.All the fatigue risk points were discovered in the sieve beam mid-span position byanalysis of ANSYS. Flexural member normal sections of reinforced concrete werecalculated according to the design code of concrete structure (GB50010-2010). Stressamplitudes of the normal section steels were presented. The fatigue lives of the structureswere calculated based on the S-N curves, which indicates allowable cycles decreases inturn in the three conditions.The allowable cycles and damage coefficients were calculated by FSTAR of ANSYSin the three conditions, which indicates fatigue life decreases in turn. Compared with thestandard calculation method, the effect of steel and concrete bonding was ignored whichmakes the results are conservative.The steel residual fatigue lives were calculated by probabilistic fracture mechanics.The calculation results show that the results of residual fatigue life which using this method is similar to the other two results. Fatigue life can be reliably and accuratelypredicted using the method. The fatigue lives of the platform are55.9,60.7,70.2years inthe three conditions under the normal using time, respectively. According to the twosituations of single vibrating screen working24hours a day and two vibrating screenworking24hours a day, the structure life reduced to19.3and19.3years, respectively.Given this, structure reinforcement can extend the fatigue life..