For a typical steel framed 30 ft by 30 ft office building bay, the fre-quency will be in the 5-8 Hz range. Frequency is a function of span (the longer the span, the lower the frequen-cy) and weight supported (the heavier the floor and the supported contents, the lower the frequency).
The following medical conditions are some of the possible causes of Skin color changes. There are likely to be other possible causes, so ask your doctor about your symptoms. 1  Causes of skin whitening:  Vitiligo.
An uneven skin tone is most commonly caused by UV rays from the sun, however, age, hormonal changes, chemicals, and pollutants can also cause this condition. Additionally, the body itself too can cause uneven skin tones and blotchy skin by attacking the cells that produce melanin.