Fixing a negative camber issue

By jpkraft27 Date 12-04-2018 12:21

This may be the wrong place to pose this question. I figured it would at least guve me guidance on where to post or at least ideas on how to solve my issue. I have an 18x50 i beam at 52ft. It had negative camber of 9/16" prior to being cut and welded. The problem I'm encountering is that the beam has stiffeners installed every 5 ft on the near side. I'm unable to rotate and change the zero end because it also has angle welded in the web. I'm thinking of putting it into a narrow ram machine centered on the stiffeners and pressing it out. Any other ideas would be greatly appreciated.

By Tyrone

Date 12-04-2018 13:02 Edited 12-04-2018 13:06

Hey JP,
Welcome to the Original AWS Welding Forum.

Since I no nothing about your task at hand, including risk to public safety if things go sideways... I'll give you my 2 cents that you should take with a grain of salt.

If possible, I would free most of the stiffeners on two sides before applying the ram. You could remove the welds or cut the stiffeners reweld after.

Again, I'm throwing out a possible solution not knowing your situation.

Tyrone

PS - I would have posted this question in the "General Welding or Technical Discussion" section. People view those threads more often.

By 803056

Date 12-04-2018 14:57

Have you considered using heat to alter the camber?

The minimum temperature differential needed to see permanent movement is about 220 degrees F above the ambient temperature. As the thermal gradient increases, there is more movement, but as long as the temperature is below the lower temperature of transformation, there should be no danger of increasing the hardness or strength of the steel.

If this is a Q&T steel, the maximum temperature should be less than the tempering temperature of the base metal.

Basically, there is no need to heat the steel to a temperature above about 800 degrees F to see significant movement.

Al

By Lawrence (*****)

Date 12-05-2018 13:59

I think Al's advice is the "mildest method" Unless that beam is built-up, and then there may be even simpler methods.

The magic of making a beam move with a little heat is nothing new, but there are very few practitioners around who really know the art/science of doing it.

One of those practitioners has published a book that I keep on my desk.

Distortion Control by John P. Stewart
https://johnstewartbooks.weebly.com/distortion-control.html

By SWN1158 (***)

Date 12-05-2018 14:08

I have that book. It's a good one, with a lot of good, practical information.