| Description |
The consideration of the dynamic effects of vibrating mineral separators on its supporting structure is crucial to design a reliable structural support system. This study evaluates the dynamic response of steel frame structures subjected to harmonic vibrations caused by mineral separators (screens). The goals of this study are to determine the parameters controlling the structural response of the supporting system, and to provide practical methods to reduce the vibrations on the steel frames at the design stage. In this study, the behavior of a steel frame structure supporting a vibrating screen was investigated through numerical analyses and field experiments. The dynamic response of the supporting frame structure recorded from field experiments was compared to computer-based dynamic analysis results. For this purpose, structural models were developed in the software program SAP2000 to predict the dynamic behavior of the supporting steel frames under harmonic vibrations; whereas, during the field experiments, accelerometers recorded the steel frames' vertical and horizontal dynamic response. The results indicate that the harmonic vibrations caused by the screen can cause large dynamic amplifications in the vertical direction for expected floor fundamental frequencies. Because the system's natural frequency depends on its mass and stiffness, excessive vibration in the supporting structure can be controlled by using passive vibration control methods such as isolators, dampeners and structural design modifications. In this thesis, modification of the structural dynamic properties was the only option investigated due to several restrictions on the other options. Thus, the selected design options depend on the magnitude of the ratio of forcing frequency of the screen and the natural frequency of the system f / fn. For the systems investigated, vertical vibrations can be evaluated in isolation considering only the bay where the screen is located. The simply supported beams tend to isolate the vertical vibration from the rest of the structure. Whereas vertical vibrations are a local phenomenon, horizontal vibrations are usually affected by the overall building's response. Finally, it was concluded that the weight of the material in the screen has a negligible effect on the system's frequency, even in the vertical direction. |
