Beam check

[volunteera]

Newly installed valve is a ton heavier than the previous one and has a support pack located straight underneath which is welded to platform deck. As such, the deck beam which accommodates the valve support needs to be checked.

What I all have is geometry of that beam and new weight of the valve. Unfortunately, the other existing loads are unknown yet. What would you do in this case with this level of information? Would utilization factor give us something to play around? One of the cases would be to work out utilization factor of the beam for only new valve weight and then add the factor to global structural model.

Thanks in advance!

 

[TehMightyEngineer]

I suspect you actually can get a reasonable idea of the loads the beam needs to take; it would be very unusual that you couldn't figure out the dead and expected live load for a beam.

Alternatively you could figure out the allowable capacity of the beam, subtract the moment and shear caused by the valve, and then see if what remains is sufficient for an estimate of the dead and live load on the beam.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[volunteera]

The beam is part of an offshore platform deck structure and is in joint with some other beams through the length. In addition it accepts a few more existing valves where again the weight is unknown. Your solutions are both reasonable however i would wonder if is applicable to my issue. Maybe i do not interpret it correctly?

I think if i work out utilization factor of the beam in basis of the additional load added on the beam as the result of weight difference then the third party who possesses the general model can advise if this passes allowables in combination with existing loads. Am i beaing over conservative here?

Thanks for typing back btw.

 

[Teguci]

Assume that the existing beam system (beam, connections, welds, etc...) is at capacity under the existing loading condition. Supplement the beam (flange plates, brace, etc...) for the entire additional surplus load. Carry this through the structure until the impact of this additional load is something like 5% of capacity or less.

 

[volunteera]

I am not sure why i have to carry the additional load through the structure as i do exacly know where it needs to be applied.

Is this 5 percent general engineering practice or is there any references?

 

[TehMightyEngineer]

There is actually a provision in many building codes for existing structures where you can ignore the effects of increased loads relative to the original design load. For example; the ICC Existing Building Code. However, if this is an offshore platform then it likely has it's own code provisions. 5% is just a typical safe assumption that many engineers use.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com