Welded/Bolted Shear Conns. VS Bolted/Bolted

[NBEEBE]

Hi, I'm just wondering if anyone sees a reason why bolted/bolted connections for beam to girder connections in steel buildings are not often seen in steel construction in California. I am a detailer for a fabricator in California and we never see bolted/bolted connections being used on contract drawings. With the use of automated equipment in our shop it would be very beneficial in my opinion to be able to bolt angle clips rather than fit up and weld shear plates on girders. Less inspection, less qualified labor required, and a lot less fit up time. I'm not sure if being within certain seismic zones could play a role in this or not. It seems if a bolted/bolted connection can resist the shear forces shown on the contract drawings there wouldn't be any issue in using these. I often think we as a fabricator we should see about proposing the bolted angle connection rather than the welded plates commonly seen, BUT am a little hesitant because I am merely a detailer, not an engineer, and connection design has never been needed or provided by our company. If anyone could shed some light on any reason these connections aren't seen in californa (as far as I've seen) that would be great. Thanks in advance

 

[hokie66]

Whether in California or elsewhere, most of us want to do as much work in the shop as possible (leaving fewer opportunities for the erector to get it wrong), thus welded/bolted has been the norm. Are you going to do the bolting in the shop where you would otherwise weld?

 

[fegenbush]

hokie66 nailed it. Shop hours do not equal field hours, especially in California.

 

[NBEEBE]

Agree 100%. My thought was that using an all bolted single angle connection shop attached to girders could be more efficient for us. Maybe this isn't the case, but if it were the case we would have to create an RFI and hope for approval. Just wondering if there is some underlying reason we never seem to see this type of framed connection. This could be due to what has been mentioned regarding a welded bolted connection being most efficient. Maybe i'm off base on my thought of a bolted/bolted configuration possibly being a time saver.


Looking at table 10-11 of the Manual (AISC) it looks like this connection could be sufficient in many cases.


Thanks for the input, its much appreciated

 

[connectegr]

Fabricator shop set up is an obvious consideration. With CNC beam lines and angle equipment bolted/bolted connections are much more economical. BUT...

1. West coast projects require connections to be designed by the EOR and included in the design package. Welded clip angles are easier to design and provide a little more connection capacity, relative to the connection depth. Typically seismic projects have less consideration for cconstruction; fabrication or erection, economy.

2. A fabricator's connection engineer would make different choices. Or, fabricator's familiar with the typical connections provided by the EOR may not invest in more economical equipment, that may not be used. Shop supervisors are reluctant to make equipment changes in this enviroment, which will additionally impact the labor force of welders and fitters.


3. Seismic projects may have more beam connections with axial forces. These connections are frequently done with welded clip angles. So that tearout and block shear of thin beam webs are less of an issue.

4. Industrial projects are frequently unit price projects. Large connection forces, large beam copes, connection geometry, interferences with other connections (horizontal bracing, etc) small column depths, clearance issues with bolted/bolted connections, and limited gages.

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[connectegr]

PS
For beam to girder connections, bolted/bolted single angles are the way to go. Girder and Beam simple move through the beam line. Beams are coped and loaded on the truck. Girders are positioned on their beam flange, clip angles are bolted to the end, single angles are bolted for filler connections. No fitting required, no flipping to member to provide welding position for angles or shear plates. Less skilled shop labor is required to stuff bolts and operate a TC gun.

This represents an enormous project cost impact. With adequate connection design, there is no impact on connection capacity or performance of the structure.

You should suggest this alternative or us a connection engineer to adequately explain your position.

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.