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USFOS GETTING STARTED
9.1.4.3
9-9
Description
One compression brace of the upper panel fails when the external load reach a level of __.__.
From this level, the load in the other compression brace decreases, and the load is transferred to
the compression braces of the panel. At load level __.__, a compression brace of the lower panel
fails. Again, the other compression brace is unloaded, and further loading carried by the tension
braces. At load level __.__, the full plastic capacity of the tension braces is utilized. Any further
loading is carried entirely by the legs.
9.1.4.4 Program input
Control file
Head_orig.fem
Structure file Stru_orig.fem
Additional
~
file
Load case 1 Gravity load
Load case 2
Horizontal load
9.1.4.5 Analyses
1. Perform a pushover analysis of the frame, with the following input :
No initial deformations. Local buckling formulation OFF.
Load case 1 (gravity) to load level 1.0.
Increasing Load case 2
use DENT_OFF
Activate plastic utilisation. Magnify displacements by a factor of 2. Create
axial force versus global displacement diagrams for element no’s 4, 5 and
12. Step up along the curves and explain by physical reasoning the
interrelationship between the curves. Identify maximum resistance of frame
and buckling resistance of element 4.
2. Apply initial deformation equal to 0.002 times member length and perform
pushover analysis as for the base case. Compare maximum resistance of the
frame and buckling resistance of element 4 with the base case. Plot strain
distribuition in the frame using Result/BEAM/ELEMENT/Beam strain.
Adjust fringe range to 0 – 0.15 using Results/Fringe range. Identify the
deformation state with a maximum beam strain of 0.15.
use CINIDEF
3. Activate local dent formulation and perform pushover analysis. Compare
maximum resistance of the frame and buckling resistance of element 4 with
base case. Identify initiation of local buckling on element 4 response.
deactivate DENT_OFF
4. Experiment with step-size, and equilibrium iterations
modify CUSFOS
activate/deactivate CITER
MARINTEK 2001