I don’t understand how putting a bolt through the hole strengthens the piece of steel that the hole is in.
If the heat from the weld plug has already weakened the steel it seems that the damage is already done.
Hey I'm just a stupid a$$ former ship-yard welder, who worked on the "SMALL-BOATS," 350 Ft. long, Approx. 80' Ft. wide. It's not the heat so much, as the obvious "POOR WELDS." Took a full year of Welding school, through a local community college, just a little after the earth wakes in California, had numerous different people talk to us about the new earth wake standards for rebuilding of roads (read that as bridges) we're talking a whole lot of welding (i.e. heat) going on. When something is welded, properly, the welded joint is stronger the the adjoining material. Just the simple facts.
For those arm chair welding hero's commenting, I've noticed not one of you has asked "GEE WERE THE WELDS EVER X-RAYED?" I'm guessing you didn't even know that X-Raying welds could be done. In the field, when the guy who does the X-Raying shows up, the welders refer to him / her as the un-employment guy. Why, because, if your welds fail, your FIRED!!!!
I had to weld some VERY BIG PAD-EYE'S onto the Pilot house, so they could lift the pilot house up onto the ship. Eighty feet, from the ground up, then move into place. Oh, it only weighed 120 Metric Tons' so I guess I don't know just what I'm talking about.
“I don’t understand how putting a bolt through the hole strengthens the piece of steel that the hole is in.”
The heat only weakens the surrounding area, the bolt/washer combo probably extends into the unaffected area.
Remember, this is for tension stress only. Take a piece of 30 mil shower liner (i.e., thick rubber matting) that’s 6” x 6”, drill a half inch hole through the center (if you can without tear it), then grab two sides and pull apart. The liner is very weak at the hole. Then put a half in bolt through it with washers on both sides and secure it tightly with a nut. Then try to pull it apart...much tougher - because you not only lose the advantage of the hole in helping to pull it apart, you now have a section between the washers that won’t even flex. The result is a stronger piece of 6 mil. (you have to ignore gravity in my example, as it doesn’t apply in the case of bridges).
Pretty clever fix, in my opinion.
I don’t understand how putting a bolt through the hole strengthens the piece of steel that the hole is in.
If the heat from the weld plug has already weakened the steel it seems that the damage is already done.
= = =
My first thoughts, too.
Maybe ... If they drill out past the heat affected zone, and put in a bolt to fill the new hole (and treat for corrosion resistance,etc.) ...
but now we have removed material (area) that may increase the stress, as in stress = load / area.
So, I need more data.
OR, because the Govt. is involved,
Drilling something and putting a bolt in could be called Screwing it.
“Bridge is all OK now, we Screwed it up.”