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.
What causes uneven skin tone? The main causes of uneven skin tone are hyperpigmentation, sun spots, hormones and discolouration due to acne scarring. An excess of melanin or pigment in the skin due to sun exposure creates freckles and eventually, isolated dark spots.