ABSTRACT
Vibration problems can be vexing at best and life-threatening at worst. This chapter focuses on harmonic loads caused by rotating machinery and human activity. It discusses the different types of loads: dead, live, or snow. Dynamic loads change rapidly and are repetitive or transient in nature. Periodic loads are harmonic, often sinusoidal, loads. Natural frequency represents the rate at which a structure vibrates if there are no continuous external forces present on a structure—they determine response to the input. Natural frequency is a function of stiffness and mass. The simple frequency solutions provide a starting point for vibration analysis, or for checking complex software solutions. When the forcing and natural frequencies get close to each other, resonance occurs. The result of being close to resonance may only be annoying, such as a floor vibration, but it also may cause a machine to malfunction, or lead to complete structural collapse.
