Deteriorated Web Analysis
Deteriorated Web Analysis
(OP)
We are performing the load rating of a bridge that exhibits significant corrosion of the steel webs near the abutments. The webs have holes near the bottom flanges, the largest of which is 2" high, 16" long. I am having trouble calculating the shear capacity. I am uncomfortable using the reduced web depth for calculating a conventional shear capacity (reduced d x tw x Fy), but I also believe I should not give a capacity of zero either. Is there any information out there for analyzing such a case?
Thanks for any information.
Thanks for any information.






RE: Deteriorated Web Analysis
RE: Deteriorated Web Analysis
If there is a hole near the bottom flange, then as the beam approaches the support abutment you transition into a "T" beam with the stem in tension. Assuming the web is adequately supported at the very end - you can determine a moment and shear capacity of the "T", ignoring the bottom flange altogether as it is not effective in resisting any stress at all.
RE: Deteriorated Web Analysis
The girder does bear on the bottom flange, but it doesn't at the very end due to the hole. I agree with your method for moment capacity, but what about shear?
RE: Deteriorated Web Analysis
Now with the deteriorated opening very close to the bottom flange, you will probably violate some of the min. distance requirements between opening and flange. But I do think it checks the shear across the sections with the opening either unreinforced or reinforced.
Another option would be to simply reinforce the deteriorated opening by adding a web cover plate and perhaps some horizontal stiffner plates that run from the end of the beam out past the opening. This would create a form of wide flange beam that could be checked in a traditional fashion.