Minimum Thickness Beam

[Joe254]

Greatings All,

Does it exist some code that allows to determine the minimum thickness of a beam or know guidelines with criterion to remove beams affected by the corrosion? For example, there are several beams with deterioration by corrosion with material loss which can convert in a serious working risk or operational, whence needs a fast decision, always justificed under a code or criterion.

Thanks in Advance.

 

[Agent666]

I'd imagine you are not going to find specifics that says if you loose 10% of the thickness or some percentage of the original capacity you are still ok, because the original design might have required 100% of your steel beam to work.

The only thing I can think of that might be similar is ASCE 41 (I think) used to have something for assessing the need to strengthen a beam if more load is being added, something like if the load only increases by 5% then you don't need to assess it further as a 5% increase can be tolerated without a significant drop in the safety factors that are being achieved. You could work this scenario in reverse because its more or less the same thing, if the load was kept similar and you lost 5% of your capacity, then it's similar by the same reasoning. Refer to ASCE for the exact percentages that are acceptable, I'm only remembering off the top of my head the numbers based on a webinar I viewed a while ago from AISC and strengthening of steel members.

Notwithstanding the approach I noted above (if it's deemed acceptable), each assessment of significant corrosion really depends on the load and location of the corrosion on the member. You can tolerate more loss of material where the design actions are lower for example (such as away from mid-span on a simply supported beam).

 

[atrizzy]

I'd suggest you measure the remaining thicknesses in your beam and complete an independent analysis of the remaining capacity, comparing it to the demand.

Keep in mind it's very likely you may be looking at reductions in web/flange class/compactness.