NEED TO ADD ADD_INERTIA_LOAD TO INTERFACE .. SEE EARTHQUAKE_PATTERN CLASS.

Element

#include <element/Element.h>

class Element: public DomainComponent

TaggedObject

MovableObject

DomainComponent

Element is an abstract class, i.e. no instances of Element will exist. The element class provides the interface that all element writers must provide when introducing new element classes.

// Constructor

// Destructor

// Public Methods dealing with Nodes and dof

// Public Methods dealing with State

// Public Methods for obtaining Linearized Stiffness, Mass and Damping Matrices

// Public Methods for obtaining Resisting Forces

// methods for obtaining information specific to an element

To construct an element whose unique integer among elements in the domain is given by tag, and whose class identifier is given by classTag. Both of these integers are passed to the DomainComponent constructor.

The destructor. Declared as virtual to allow subclass destructors to be invoked.

To return the number of external nodes associated with the element.

To return an ID containing the tags of the external nodes for the element.

To return the number of dof associated with the element. This should equal the sum of the dofs at each of the external nodes. To ensure this, each subclass can overwrite the DomainComponent classes setDomain() method.

virtual int commitState(void) =0;

The element is to commit its current state. To return \(0\) if successful, a negative number if not.

virtual int revertToLastCommit(void) =0;

The element is to set it’s current state to the last committed state. To return \(0\) if successful, a negative number if not.

virtual int revertToStart(void) =0;

The element is to set it’s current state to the state it was at before the analysis started. To return \(0\) if successful, a negative number if not.

virtual int update(void);

This method is invoked after the response quantities have been updated in the Domain, but not necessarily committed, e.g. during a non-linear Newton-Raphson solution algorithm. To return \(0\) if successful, a negative number if not. This base class implementation returns \(0\).

virtual bool isSubdomain(void);

The element is to return true if the element is of type (or subtype) Subdomain, else the element should return false. This base class implementation returns \(false\).

virtual Matrix &getTangentStiff(void) =0;

To return the tangent stiffness matrix. The element is to compute its stiffness matrix based on the original location of the nodes and the current trial displacement at the nodes. \[\K_e = {\frac{\partial \f_{R_i}}{\partial \U} \vert}_{\U_{trial}}\]

virtual Matrix &getSecantStiff(void) =0;

To return the elements secant stiffness matrix. The element is to compute its stiffness matrix based on the original location of the nodes and the current trial displacement at the nodes. THIS SECANT MAY BE REMOVED.

virtual Matrix &getDamp(void) =0;

To return the damping matrix. The element is to compute its damping matrix based on the original location of the nodes and the current trial response quantities at the nodes. \[\C_e = {\frac{\partial \f_{R_i}}{\partial \dot \U} \vert}_{\U_{trial}}\]

virtual Matrix &getMass(void) =0;

To return the mass matrix. The element is to compute its mass matrix based on the original location of the nodes and the current trial response quantities at the nodes. \[\M_e = {\frac{\partial \f_{I_i}}{\partial \ddot \U} \vert}_{\U_{trial}}\]

virtual void zeroLoad(void) =0;

This is a method invoked to zero the element load contributions to the residual, i.e. \(\P_e = \zero\)

virtual Vector &getResistingForce(void) =0;

Returns the resisting force vector for the element. This is equal to the applied load due to element loads minus the loads at the nodes due to internal stresses in the element due to the current trial displacement, i.e. \[\R_e = \P_{e} - \f_{R_e}(\U_{trial})\]

virtual Vector &getResistingForceIncInertia(void) =0;

Returns the resisting force vector for the element with inertia forces included. This is equal to the applied load due to element loads (loads set using addLoad(), minus the loads at the nodes due to internal stresses in the element due to the current trial response quantities, i.e. \[\R_e = \P_e - \f_{I_e} (\ddot \U_{trial}) - \f_{R_e}(\dot \U_{trial}, \U_{trial})\]

setResponse() is a method invoked to determine if the element will respond to a request for a certain of information. The information requested of the element is passed in the array of char pointers argv of length em argc. If the element does not respond to the request a \(-1\) is returned. If it does respond, an integer value greater than or equal to \(0\) is returned. This is the responseID passed in the getResponse() method. In addition the Element object is responsible for setting the Information object eleInformation with the type of the return, i.e. IntType, DoubleType, MatrixType, VectorType, IDType, and for creating a Matrix, Vector or ID object for the Information object, if the information to be returned is of any of these types. The information object is responsible for invoking the destructor on these objects. The base class responds to no requests and will always return \(-1\).

getResponse is a method invoked to obtain information from an analysis. The method is invoked with the integer argument returned and the Information object that was prepared in a successful setResponse() method invocation. To return \(0\) if successful, a negative number if not. The base class implementation will always return \(-1\).