Welded Plate Girder/Columns with "Wavy" Webs

[bf343]

We have a client who has a warehouse that is a pre-engineered metal building (PEMB). The PEMB columns and beams are welded plate girder shapes. In doing a walk through of the facility it was noticed that the webs of both the columns and beams are not flat, but are "wavy". It can easily be seen by the dust that has settled onto the outward wave of the web. In the attached pictures, the dark spots on the webs are a collection of dust. If you were to look at the opposite side of the column/beam, the dark spots would be in alternating places. The wave of the webs is noticeable to the touch of the hand. On the columns, where the web connects to the flanges, the web appears to be flat. I was unable to touch the beams, but they seem very similar.

Has anyone every seen/experienced anything like this in the past?

It seems like it must be a result of fabrication (webs continuously welded to the flanges), but is there any chance this is a sign of web buckling? Seems unlikely as the flanges show no noticeable distortion.

This link to the AISC FAQS seems to state that what we are seeing at this facility is within tolerance. However, I would still like to hear some feedback from anyone that has seen this in the past.
[URL unfurl="true"]https://www.aisc.org/DynamicQuestion.aspx?Grpid=6&QueId=1600&ste=_Preview&id=2100&type=0[/url]

 

[bf343]

Here is an additional picture. This is of a different column.

 

[sandman21]

Hard to tell how much they are "out". If its within tolerance, they are not new and no concentrated areas, I would say you are ok. The client should be more worried about the damaged columns and the conc, sleeved columns.

 

[MotorCity]

Agree w/ sandman, how far out of flat are the webs? Can't tell if they are galvanized, any chance that the discolored areas are just variations in the patina of corrosion or galvanization?

The patterns are not consistent with the classical tension field pattern that can develop due to load, so if I had to guess, the members were either fabricated that way or became that way due to weld distortion which typically occurs in thin (i.e. PEMB) members.

 

[bf343]

The height of the wave is about 1/4" or less. Not an extreme amount.

Sandman21 - The damaged columns are why we were there.

MotorCity - The discolored areas are dust and grime collection. I cleaned a couple spots off while there.

We felt it had to be from fabrication, but wanted to get some other opinions on the issue. If you zoom in on the first picture (2016-04-20 120) you can see the dark spots on all the frames in the building.

 

[ajh1]

The MBMA standard tolerance for out of flat on a web is depth / 72. For the longitudinal waves in these pictures that is from the assumed straight position of the web, i.e., theorectical centerline to the top or bottom of a wave. High point to low point on a wave would be double that.
A lot of these types of issues are caused by the shrinkage of the flange to web weld longitudinally. If the web is lighter than the flange, which is typical, then the web can develop these waves as the flange shrinks during cooling. Conversely, if the web is heavy with light flanges, typical for situations where the beam is designed for deflection control rather than stress, the flanges may exhibit a twisting wave (much more problematic).
I would concur that the damage to the lower portion of the column in the second picture is of more concern than the web waves.

 

[sandman21]

You might want to ask about the conc. and see who added it, how it was added, etc. Adding stiffness to some columns and not others can be problematic.

 

[bf343]

Thanks for the great replies.

ajh1 - Thanks for the tolerance reference. The deepest column at the facility is 17", so 17/72 = 0.236" Therefore the 1/8" wave (1/4" high point to low point) is well within this.

We were asked to do a facility wide review of their column damage. Majority of it is due to fork truck traffic. The concrete encasement around the base of some columns was the owners attempt at stabilizing a column that was damaged by a fork truck. We have repair and/or replacement procedures in the works for the damaged columns.