temporary bracing steel frame - oash et al??? 2

[scherry]

I have no idea how I wind up in these situations but...I have been asked to review a temporary bracing and erection proceedure plan for a steel framed building. I am not the SER, and I am not working directly with the erector. my contact is the general. I have been beating the bushes trying to find enough information to be sure I am comfortable with it. I have spoken to the pipe brace manufacturer for tilt walls, which the erector is using to brace the columns and they said yeah they have heard of people doing it and they guess it's ok...and I have downloaded the OSHA criteria and the mnanual of standard practise and read through the code - ubc, and, well... I have looked at the 300 pound load eccentric to the column (OSHA) and of course I have figured out the dead load of the steel beams and columns, but I am at a loss for what to look at for wind. Does it make sense to use the coefficients for the main frame and then apply them to the surface area of the membvers in the frame? Should I use instead open tower coefficients (which I suspect are very conservative for this application). Can I take a 1/3 increase for wind loads? Anyone do any of this and have any comments or suggestions? Also since we are mentioning OSHA, can the requirement for a four bolt pattern be designed around? if for example and this is hypothetical, I have someplace where I must conceal a connection and need to use only two bolts can I specifiy erection bracing until the column is stabilized permanently?

thanks for any help you can give.

 

[Kicker06]

The only advice I could give you is simply, BE CAREFUL! Our policy here at our office is that we DO NOT tell a Contractor how to do their work, or approve their methods. That is the responsibility of the contractor, not the consultant. Also, I would mention that if you do not have the ability to control the means and methods of installation, I would not make a recommendation.

good luck.

 

[scherry]

Thanks for the response. Unfortunately it agrees with what i have always thought too, but i think my situatiuon is different. Because then the question is...WHO does design this stuff? someone has too, right? is there a whole other branch of engineering that just does work for contractors on the construction end rather than for owners for the building design? And in this case i am the consultant to the CONTRACTOR not to the Owner, so ...?

thanks again for any input.

 

[SlideRuleEra]

scherry - Yes, there are engineers who support contractor's efforts. Larger contracting firms often have a small professional staff, smaller contractors hire consultants (but sometimes only when forced to do so). Some Owners have contract requirements that temporary structures be designed & approved by a PE.
At this point, I recommend Kicker06's advice. Addtionally you may try asking your contractor for written responses to your questions about his plans. At a minimum you should be able to make him think seriously about the situation.

 

[jheidt2543]

A few comments:

1. Yes, there are a lot of engineers that work directly for conctractors and frankly I get a little tired of the attitude that ALL contractors are hicks in pickup trucks. I've met many and worked for some that have more practical building knowledge and engineering insight that some of the engineers that design the stuff the contractor is supposed to build! Lets face it guys, some of the designs we see are put together without any thought of how it goes together. If the contractor is smart enough to hire an engineer to review his erection plan, then he deserves one "atta'boy" from me.

2. The first thing I would do, after a though review of the deisgn drawings, is sit down with the contractor and outline how he plans to erect the building - step by step. That process will govern the temporary bracing format.

3. Most contactors have a good idea of the sequence they want to use to erect a building from the bidding process. The good ones just don't figure $/ton or $/sf, they actually prepare a bid based on pricing the sequences of the erction process. Your job is to provide the engineering support for that method.

4. As to the four (4) bolt requirement, IMHO, if you design an alternate bolt pattern to carry the building loads as well as the temporary loads, then I see no problem. I would provide a note that additional temporary bracing is required in that location until final connections are made. You are designing the erection process with the contractor so, you want to make clear what should be done to safely erect the building.

5. Work with/for people you trust.