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CentralDifference.h

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00001 /* ****************************************************************** **
00002 **    OpenSees - Open System for Earthquake Engineering Simulation    **
00003 **          Pacific Earthquake Engineering Research Center            **
00004 **                                                                    **
00005 **                                                                    **
00006 ** (C) Copyright 1999, The Regents of the University of California    **
00007 ** All Rights Reserved.                                               **
00008 **                                                                    **
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00011 ** file 'COPYRIGHT'  in main directory for information on usage and   **
00012 ** redistribution,  and for a DISCLAIMER OF ALL WARRANTIES.           **
00013 **                                                                    **
00014 ** Developed by:                                                      **
00015 **   Frank McKenna (fmckenna@ce.berkeley.edu)                         **
00016 **   Gregory L. Fenves (fenves@ce.berkeley.edu)                       **
00017 **   Filip C. Filippou (filippou@ce.berkeley.edu)                     **
00018 **                                                                    **
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00020 
00021 // $Revision: 1.4 $
00022 // $Date: 2005/12/19 22:43:36 $
00023 // $Source: /usr/local/cvs/OpenSees/SRC/analysis/integrator/CentralDifference.h,v $
00024 
00025 
00026 #ifndef CentralDifference_h
00027 #define CentralDifference_h
00028 
00029 // Written: Andreas Schellenberg (andreas.schellenberg@gmx.net) 
00030 // Created: 02/05
00031 // Revision: A
00032 //
00033 // Description: This file contains the class definition for CentralDifference.
00034 // CentralDifference is an algorithmic class for performing a transient analysis
00035 // using the central difference integration scheme.
00036 //
00037 // What: "@(#) CentralDifference.h, revA"
00038 
00039 #include <TransientIntegrator.h>
00040 
00041 class DOF_Group;
00042 class FE_Element;
00043 class Vector;
00044 
00045 class CentralDifference : public TransientIntegrator
00046 {
00047 public:
00048     // constructors
00049     CentralDifference();
00050     CentralDifference(double alphaM, double betaK, double betaKi, double betaKc);
00051 
00052     // destructor
00053     ~CentralDifference();
00054     
00055     // methods which define what the FE_Element and DOF_Groups add
00056     // to the system of equation object.
00057     int formEleTangent(FE_Element *theEle);
00058     int formNodTangent(DOF_Group *theDof);        
00059     
00060     int domainChanged(void);    
00061     int newStep(double deltaT);    
00062     int update(const Vector &U);
00063     int commit(void);
00064     
00065     virtual int sendSelf(int commitTag, Channel &theChannel);
00066     virtual int recvSelf(int commitTag, Channel &theChannel, FEM_ObjectBroker &theBroker);
00067     
00068     void Print(OPS_Stream &s, int flag = 0);        
00069     
00070 protected:
00071     
00072 private:
00073     double deltaT;
00074 
00075     // rayleigh damping factors
00076     double alphaM;
00077     double betaK;
00078     double betaKi;
00079     double betaKc;
00080     
00081     int updateCount;                // method should only have one update per step
00082     double c2, c3;                  // some constants we need to keep
00083     Vector *Utm1;                   // disp response quantity at time t-deltaT
00084     Vector *Ut, *Utdot, *Utdotdot;  // response quantities at time t
00085     Vector *Udot, *Udotdot;         // response quantities at time t+deltaT
00086 };
00087 
00088 #endif

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