help me for modal analysis of steel structure
 

i want to make modal analysis of steel structure

Problem Description
Section properties:
Columns:
Box section 4 x 4 cm, thickness 2 mm
Beams:
Box section 4 x 2 cm, thickness 1.5 mm

Material properties:
Weight per unit volume γ = 7.849 t/m3
Poisson’s ratio σ = 0.3
Modulus of elasticity E = 2x107 t/m2

Weight of steel plates:
140 kg at each floor
Their mass is concentrated at columns

Notes:
• All column to beam connections are completely rigid
• Columns are fixed at base.

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i want to ask about

1- element type
2- meshing options
3- how to apply loads due to weight
4-how to get the damping with natural frequencies and mode shapes
5- 'All column to beam connections are completely rigid; what is the mean of this statement in the options of analysis