General > Add_Damping2State

`Add_Damping2State`

## Purpose

setup damping matrix of structural model as field of data structure STATE

## Synopsis

`State = Add_Damping2State (type,Model,State,zeta,mode)`

## Description

ADD_DAMPING2STATE setup damping matrix of structural model as field of data structure STATE STATE = ADD_DAMPING2STATE (TYPE,MODEL,STATE,ZETA,MODE) the function sets up the structural damping matrix C as a field of data structure STATE the free DOF stiffness matrix is supplied in the field Kf of STATE and the free DOF lumped mass vector in the field Ml of MODEL; the damping matrix is calibrated so that the mode numbers in row vector MODE have the damping ratios specified in the row vector ZETA; the character variable TYPE should be either 'StifProp', 'Caughey' or 'Modal' Note: Caughey with one mode reduces to a mass proportional damping matrix and with two modes reduces to Rayleigh damping; for more than 2 modes Caughey damping works only if Ml is fully populated; Modal damping refers to the method of superposing modal damping matrices by Wilson/Penzien; reference: Chopra, Dynamics of Structures, 2nd edition, pp. 455-463

## Cross-Reference Information

This function calls:

- Create_Damping setup damping matrix of structural model