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| Bar stuck on both the top and bottom flanges can help, but only a limited amount. The weld has to be really good and then the web will be a little thin in proportion and be the weak point. The added bars will try to separate from the existing flange by shear and the web will tend to rip end to end from shear with the added bars. Its important for a beam to be monolithic to achieve the full strength.
The bending strength of a solid bar is proportional to b * h * h * h /12 where b is the width, and h is the height. A little more height goes a long ways to strength because of that cubic factor. To figure the strength of a flanged beam you start with that formula on the outside dimensions, then subtract the air area between the flanges and the web, twice.
There is little substitute for height. 20% added height gets 73% added strength. But it takes 73% added width to get 43% added strength holding the height constant.
Better in the original question to get a taller beam and recess part of it into the ceiling.
Gerald J. | |
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How much weight will this I beam support?
