Structural Steel Quantity & Cost Estimates

[JoelTXCive]

I have a steel platform project that we are preparing a 30% submittal on. Part of this submittal will be estimated quantities.

We have no idea what we are going to build for this project, but heaven forbid we stop the production train from rolling.

So.... I need to come up with some quantities for an imaginary steel structure.

Isn't there a rule of thumb for connector weights as a percentage of the main structure's weight?

For example, if I come up with 50,000lbs of beams and columns for my platform, then connectors will be approximately another XX% ?

Thank you in advance.

 

[GC_Hopi]

Others may have a better feel for this but I have used 10% to 15% adder on the weight to account for connection the exact percent is a SWAG based on the size and complexity I expect for the connections. There are better sources but I can think of any at the moment. Here is some anecdotal evidence.

 

[MotorCity]

We do not add anything for the weight of typical shear and moment type connections. An estimate is just that.....an estimate. Even if connections add 3% to the weight, there's no way our engineer's estimate will be within 3% of the final tonnage. At 30% level of completion, I'd be surprised if your takeoff was within 20% of the actual tonnage. If someone twisted my arm into taking a stab at connection weight, I'd probably throw another 3 to 5% on it. For reference, I don't think the Sideplate example referenced above is a fair representation of what I would consider a "typical" connection. Those connections use very large plates which will naturally tend to weigh alot more than say a double clip angle or shear tab connection.

 

[human909]

3% is a pretty low figure in my experience in steel fabrication. 5-10% depending on the type of job was what I used to use and I'd normally be within 1%. But context is everything. Both the type and size of the design.

 

[JoelTXCive]

Thank you all.

I'm just going to throw 10% on at this point.

This will be a steel platform for a ~200kw generator and control building.

The site plan hasn't been completed; the electrical engineers have not picked the generator yet; or their control building geometry......but we have to make a submittal so that a box on the project schedule can be checked.

Crazy government jobs....

 

[Brad805]

At a 30% DD estimate I would use a cost /lb for the steel.