WiSEiwish
Structural
- Mar 28, 2013
- 123
Engineers,
I am going through AISC 13th Section J10 and trying to get my head wrapped around the stiffener requirements. From what I gather there are three different types of transverse stiffeners:
Full Depth (extending from one loaded flange to the opposite “k”)
Partial Depth (extending from one loaded flange to at least the midpoint of the web)
Fitted (extending from one loaded flange to the opposite loaded flange)
I want to make sure that I have a good grasp on the usage for each stiffener. I think that I have a good understanding as to where to use both Full Depth and Partial Depth stiffeners, but I don’t really know when Fitted Stiffeners would be required. If anyone could shed some light on this and correct me if I am misunderstanding something that would be fantastic. Here is my current understanding:
Full Depth Stiffeners: These are use to reinforce the web at unframed ends of beams and girders (J10-7) and web compression buckling (J10-5)
Partial Depth Stiffeners: These are used for the other governing conditions except those that require full depth stiffeners
Fitted Stiffeners: These are used when there is a pair of concentrated forces acting at the same location e.g. both flanges require reinforcing.
Are there any other reasons to use fitted stiffeners? It seems like they should be avoided when possible as they are going to be much more expensive to fabricate and install due to the precise dimensional requirements. Also is a check for bearing only required when the stiffener is fitted? This seems to be supported in the statement “For fitted bearing stiffeners, see Section J7”
With regards to welding requirements I have a few questions there as well.
“The welds of the flange shall be sized for the difference between the required strength and available limit state strength.” This means that the weld capacity has to support the actual load – flange capacity?
“The stiffener to web welds shall be sized to transfer to the web the algebraic difference in tensile force at the ends of the stiffener.” This I am not so sure about. It would seem that if the stiffener were partial depth then the algebraic difference is whatever force is resisted by the stiffener – 0 as there is no support on the other side. For a fitted stiffener, would welds on the web even be required?
“The weld connecting full depth bearing stiffeners to the web shall be sized to transmit the difference in compressive force at each of the stiffeners to the web.” There is nothing here regarding the welding of the stiffener to the flange. Does the quote indicate that the weld should simply be strong enough to take the difference in the required strength and capacity?
I’m sure there is a lot more to know, but I figured I would start there.
I am going through AISC 13th Section J10 and trying to get my head wrapped around the stiffener requirements. From what I gather there are three different types of transverse stiffeners:
Full Depth (extending from one loaded flange to the opposite “k”)
Partial Depth (extending from one loaded flange to at least the midpoint of the web)
Fitted (extending from one loaded flange to the opposite loaded flange)
I want to make sure that I have a good grasp on the usage for each stiffener. I think that I have a good understanding as to where to use both Full Depth and Partial Depth stiffeners, but I don’t really know when Fitted Stiffeners would be required. If anyone could shed some light on this and correct me if I am misunderstanding something that would be fantastic. Here is my current understanding:
Full Depth Stiffeners: These are use to reinforce the web at unframed ends of beams and girders (J10-7) and web compression buckling (J10-5)
Partial Depth Stiffeners: These are used for the other governing conditions except those that require full depth stiffeners
Fitted Stiffeners: These are used when there is a pair of concentrated forces acting at the same location e.g. both flanges require reinforcing.
Are there any other reasons to use fitted stiffeners? It seems like they should be avoided when possible as they are going to be much more expensive to fabricate and install due to the precise dimensional requirements. Also is a check for bearing only required when the stiffener is fitted? This seems to be supported in the statement “For fitted bearing stiffeners, see Section J7”
With regards to welding requirements I have a few questions there as well.
“The welds of the flange shall be sized for the difference between the required strength and available limit state strength.” This means that the weld capacity has to support the actual load – flange capacity?
“The stiffener to web welds shall be sized to transfer to the web the algebraic difference in tensile force at the ends of the stiffener.” This I am not so sure about. It would seem that if the stiffener were partial depth then the algebraic difference is whatever force is resisted by the stiffener – 0 as there is no support on the other side. For a fitted stiffener, would welds on the web even be required?
“The weld connecting full depth bearing stiffeners to the web shall be sized to transmit the difference in compressive force at each of the stiffeners to the web.” There is nothing here regarding the welding of the stiffener to the flange. Does the quote indicate that the weld should simply be strong enough to take the difference in the required strength and capacity?
I’m sure there is a lot more to know, but I figured I would start there.
