What are the alternatives for horizontal bracing system?

[Amr Abdelhalim]

There is a steel pipe rack with normal framing system including horizontal and vertical bracing systems, all the connections of the horizontal bracing are defected, for some reasons it is nearly impossible to re-weld the connections without a shutdown for the operation. What are the alternatives for horizontal bracing system? For example adding new members and removing the horizontal bracing members completely as in the portal framing which is an alternative for vertical bracing.

 

[jayrod12]

Yes you could use moment connections to create a horizontal moment frame, search vierendeel truss.

But it's likely as much or more work than fixing the current horizontal bracing system.

We don't know enough about the layout to comment much further than that.

 

[oldestguy]

Can you make up a clamping device to fit on and bolted on the vertical below the bad joint and have this clamp also have a shelf to fit under the horizontal leg as a cradle? Then when time is available, weld this clamping device to both the vertical and the horizontal storage parts. Can also be done by no bolts, but hold in place while welding.
Edit: The reinforcement might be from angle sections to fit on the pipes of the supports, whether angle or pipe sections..

 

[HTURKAK]

There is a steel pipe rack with normal framing system including horizontal and vertical bracing systems, all the connections of the horizontal bracing are defected,

What is normal framing system ? What is the reason for horizontal bracing(s)?

Vertical bracing is used to transmit the longitudinal forces to the foundations but the use of horizontal bracing is an optional requirement for the Anchor and guide forces.

Check the guide/anchor locations (on the transverse Bent Beam), the (new) horizontal bracing could be added to near bay, and then remove the existing one(s) ..

 

[BAretired]

Amr,
There are many types of pipe racks. You have told us very little about yours. A photograph would help.
Perhaps there is something in the following article which would help:

thread507-423939

BA

 

[r13]

Provide a plan, or an elevation view, and identify the "defected" (deflected/buckled?) members. Where is the structure located, does the frame system has adequate expansion joint?

 

[oldestguy]

You questioners should know that this guy's pipe rack has no decent resistance to racking 90 degrees to the pipes supported and depends on the joints at the product supports to take this moment. Tell him how to reinforce these joints other than by re-welding alone.
This is the same problem one has with a wobbly kitchen table. The joint at the leg to the top has to withstand a moment when you have to get away from that big meal by pushing on the table to get you out from under it. Those support horizontal parts of the racks can't have diagonal in the way of the storage. Basically his joints are not strong enough to take the sideways horizontal loads perpendicular to the pipes supported.

So for the time being place diagonal struts outside of the rack system to keep movements from going so far that the product supported drops down or even lays over sideways.. May look like a mess, but that would stop the sideways movements causing the welds to fail..

 

[r13]

Note that a beam column joint has several horizontal members. You need to establish the direction of failures - longitudinal in direction of the pipes, or transverse side swings, and investigate the potential cause of these failures. Any repair work won't hold for long unless you have pin pointed the source of problem.

 

[Amr Abdelhalim]

Here is the layout for the plan

 

[Amr Abdelhalim]

And here is the failed horizontal bracing connection, failure is in the welds of both clip angles attached to the webs.

 

[Amr Abdelhalim]

After investigation it was found that the failure of the connection was due to bad application of weld since construction, re-welding the clip angle is nearly impossible without complete shutdown.

 

[r13]

Is this pipe rack inside of refinery? Can you weld without shut down?

 

[JLNJ]

It looks like an improperly designed connection which put the clip in tension.

Maybe you can field drill the connection to make it a bolted rather than welded connection, but you still will have the tensile force on the clip to resolve. Or maybe the flexing of the clip sends the force elsewhere.

 

[structSU10]

You could look into lindapter connectors - they can be installed without drilling or welding.

 

[KootK]

Maybe you can field drill the connection to make it a bolted rather than welded connection

This should be doable. Looking at the connection configuration, it looks as though the intent was pure shear.

 

[r13]

My thoughts align with JLNJ, it seems the connection has subjected to combined shear and tension, either due to lack of flexibility, or pre-tension due to fit-up during construction. I think OP should map the failed joints to have better feel of the potential causes from global view point.