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Service Load & Ultimate Load

Service Load & Ultimate Load

Service Load & Ultimate Load

(OP)
What is the difference between Service & Ultimate Load?

Thank you very much.

RE: Service Load & Ultimate Load

42

RE: Service Load & Ultimate Load

(OP)
Can you please give me a definition for both the said load.
Thanks

RE: Service Load & Ultimate Load

Sounds like you're new to structural engineering. Here's a good link explaining a lot of the basic concepts involved in structural engineering: http://www.bgstructuralengineering.com/

To answer your question,
Service Loads represent the actual imparted loads on a structure.
Ultimate Loads take the service loads, and amplify (increased typically, but not always) them to represent the loads we design for.

For example, if I have a concrete floor that is 4" thick, it weighs 50 pounds per square foot (psf). This is called the "Dead Load." Let's also assume the use of this floor is a residential space, which requires a 40 psf "Live Load."

So... Our Service Loads are 50 psf Dead Load, and 40 psf Live Load.

In Load and Resistance Factor Design (LRFD), we amplify these loads to find our Ultimate Loads based on a number of "Load Combinations" outlined in the local building code (which generally reference ASCE 7-10 in the US).

The most common "Load Combination" is: 1.2 * Dead Load + 1.6 * Live Load
So, our Ultimate Load would be 1.2(50) + 1.6(40) = 124psf

Essentially, in LRFD, the Ultimate Load is the Service Load with a "Factor of Safety" included.*
*not an exact definition but I think it'll do for what you're asking.

RE: Service Load & Ultimate Load

Based on the way you're asking service probably means unfactored and ultimate means factored.

RE: Service Load & Ultimate Load

What's this for? Is this for design of some component where wind or seismic forces are given as service or ultimste?

RE: Service Load & Ultimate Load

(OP)
@DETstru: Thanks for the reply and for the link...i really appreciate it...

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