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HHT1.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 **                                                                    **
00009 ** Commercial use of this program without express permission of the   **
00010 ** University of California, Berkeley, is strictly prohibited.  See   **
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 **                                                                    **
00019 ** ****************************************************************** */
00020                                                                         
00021 // $Revision: 1.4 $
00022 // $Date: 2003/02/14 23:00:48 $
00023 // $Source: /usr/local/cvs/OpenSees/SRC/analysis/integrator/HHT1.h,v $
00024                                                                         
00025                                                                         
00026 #ifndef HHT1_h
00027 #define HHT1_h
00028 
00029 // Written: fmk 
00030 //
00031 // Description: This file contains the class definition for HHT1.
00032 // HHT1 is an algorithmic class for performing a transient analysis
00033 // using the HHT1 integration scheme.
00034 //
00035 // What: "@(#) HHT1.h, revA"
00036 
00037 #include <TransientIntegrator.h>
00038 
00039 class DOF_Group;
00040 class FE_Element;
00041 class Vector;
00042 
00043 class HHT1 : public TransientIntegrator
00044 {
00045   public:
00046     HHT1();
00047     HHT1(double alpha);
00048     HHT1(double alpha, double alphaM, double betaK, double betaKi, double betaKc);        
00049 
00050     ~HHT1();
00051 
00052     // methods which define what the FE_Element and DOF_Groups add
00053     // to the system of equation object.
00054     int formEleTangent(FE_Element *theEle);
00055     int formNodTangent(DOF_Group *theDof);        
00056 
00057     int domainChanged(void);    
00058     int initialize(void);        
00059     int newStep(double deltaT);    
00060     int update(const Vector &deltaU);
00061 
00062     int commit(void);
00063 
00064     virtual int sendSelf(int commitTag, Channel &theChannel);
00065     virtual int recvSelf(int commitTag, Channel &theChannel, 
00066                          FEM_ObjectBroker &theBroker);
00067 
00068     void Print(OPS_Stream &s, int flag =0);        
00069     
00070   protected:
00071     
00072   private:
00073     double alpha;
00074     double gamma;
00075     double beta;
00076 
00077     double alphaM, betaK, betaKi, betaKc;
00078 
00079     double c1, c2, c3;  // some constants we need to keep
00080     Vector *Ut, *Utdot, *Utdotdot; // response quantities at time t
00081     Vector *U, *Udot, *Udotdot; // response quantities at time t + delta t
00082     Vector *Ualpha, *Udotalpha; // response quantities at time t+alpha delta t
00083 };
00084 
00085 #endif
00086

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