Biaxial compression in steel membrane structure

[enginerding]

Does anyone have a good reference for designing for biaxial compression in steel plates for water storage structures? AWWA D100 provides membrane buckling capacities where the stresses are uniaxial compression or compression with hoop tension, but states that biaxial compression is beyond the scope of the specification.

I need some reference that includes this. Can anyone make a recommendation?

 

[ishvaaag]

If flat plates in biaxial compression I would look around fig. 4.31 at p. 177 in

Guide to Stability Design Criteria for Metal Structures, 5th edition
Theodore V. Galambos
Wiley 1998

The figure gives a quick look to the kind of interaction between the compressive stresses for elastic buckling; in slender plates, elastic buckling will happen first and is of course a safe limit to work with.

If curved plates with curvature then we need to look unto the buckling of shells with single or double curvature. If you are dealing with some shell please state the geometry and we may look deeper for the case.

 

[ishvaaag]

Well the figure is at p. 178

 

[enginerding]

It is a double curved membrane. Actually it is in reverse double curvature, which is the reason for the biaxial compression.

By reverse curvature I mean that the radius of the cross section is outside the section. Picture a single pedestal steel water tower, for example. The transition between the ball cone and the pedestal or the transition between the pedestal and the base cone both have reverse double curvature.

 

[ishvaaag]

Printout of one worksheet I once made...

http://www.google.es/url?sa=t&rct=j...18mpDA&usg=AFQjCNE8duFaGA3B2cUYR05uJ9KATm5s0A

Point 4 for double curvature shells taken from the Haas reference that sells miserably at $0.85 plus postage cost, make a search...

Design of Thin Concrete Shells: Vol. 2 - Negative Curvature Index (Hardcover)

Even if for concrete the formulations are in elastic terms hence quite likely mostly applicable to steel...

As much practically, showing your worse case in FEM stabilizes in permissible way when accounting for material and geometrical nonlinearities, and for so thin shells, taking unto account large deformations, will clear you from the buckling concern.

 

[ishvaaag]

... (for the FEM way) taking of course unto account reasonable -worse case- initial imperfections.

 

[enginerding]

Anything in English?

 

[ishvaaag]

Related documentation even if may not meet your need (an eurocode doc)

I would inspect if the draft has come to code form... haven't done yet.

http://files.engineering.com/getfile.aspx?folder=55469d9f-d10c-402b-8b07-0c

 

[ishvaaag]

Eurocode 3 — Design of steel structures — Part 1-6: Strength and Stability of Shell Structures

BS EN 1993-1-6:2007

The European Standard EN 1993-1-6:2007 has the status of a British Standard

Hence the draft has become an eurocode. By the index, it seems does not addresses the buckling of double curvature shells.