Slender Colums Flashcards
What may happen if a column is relatively slender?
It may deflect laterally when subjected t a compression force, P and fail by bending rather than direct compression.
What is the ‘buckling’ of columns?
When a slender structural member is loaded with an increasing axial compression force, the member deflects laterally and fails by combined bending and compression, rather than direct compression alone.
What is the critical load of a structure?
The load which creates the borderline between stable and unstable equilibrium of the structure .
What does P,cr equal?
pi^2 * E * I / effective length
What is the 4 different effective lengths?
Fixed-fixed = 0.5
fixed-pinned = 0.7
pinned - pinned = 1.0
fixed - open = 2.0
What is the slednerness ratio?
L / i , where i is the radius of gyration
What is i, the radius of gyration ?
Root (I /A)
What does pcr equal in terms of the slenderness ratio?C
P,cr = pi^2 * E / (slenderness ratio squared)
When does crushing occur in terms of pcr and fcd?
Crushing occurs when pcr > fcd
When does buckling occur in terms of pcr and fcd?
Bucking occurs when pcr < fcd
In braced columns, what are the columns designed to do / not to do?
Braced columns are not designed to resist lateral loads, whereas unbraced columns are designed to resist lateral loads.
When calculating the effective length of a braced member, wjat are the values of k for fixed and pinned conditions?
Ki —- infinity for pinned end condtion
ki —- 0 for rigid end conditions
What 2 directions is slenderness calculated in?
Both x and y directions
What are second order effects?
Additional action effects caused by structural deformations
Quick … how do you find the slenderness of a column?
1 - Find the slenderness ratio
2 - If the slenderness ratio is larger than the slenderness limit, second order analysis is required.
