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A VARH element is defined as follows :
The member has the properties of a symmetric I section (Formcode=1), where only the height is linear variable along the member. The system length for buckling around the local yy-axis (strong axis), is equal to member length.
For this non-prismatic section, the critical Euler force is given in the next section.
For a VARH element we can define:
|
ky |
buckling coefficient around the yy-axis |
|
Ly |
system length around the yy-axis |
|
Iy, max |
maximum moment of inertia around the y-axis |
| Iy, min | minimum moment of inertia around the y-axis |
|
Iy,eq |
equivalent moment of inertia around the y-axis |
|
E |
modulus of Young |
|
Ncr,y |
critical Euler force around the y-axis |
Hirt and Crisinel (Ref[10],pp. 291) present expressions for the elastic critical load of axially loaded non-prismatic members of double symmetric cross-sections (i.e. I-sections formcode 1). Flexural buckling about the strong axis of the cross-section occurs for:
where:
And C is a coefficient that depends on the parameter r, defined as the ratio between the minimum and the maximum moments of inertia.
For a tapered member:
