# Elastic Section for Sensitivity
Both 2-D and 3-D elastic sections are available for response sensitivity computation.
```tcl section Elastic $secTag $E $A $Iz <$Iy $G $J> ```

secTag

unique section object integer tag.

E

Young’s modulus.

A

cross section area .

Iz

second moment of area about the local z-axis .

Iy

second moment of area about the local y-axis (optional, used for 3-D analysis).

G

shear modulus (optional, used for 3-D analysis).

J

torsional moment of inertia of section (optional, used for 3-D analysis).

For 2-D elastic sections, the sensitivity parameters can be: E, A, I.
For 3-D elastic sections, the sensitivity parameters can be: E, A, Iz, Iy, G, J.