Method newStep

SRC/analysis/integrator/HHTExplicit_TP.cpp:133–201

int HHTExplicit_TP::newStep(double _deltaT)
{
    updateCount = 0;
    
    if (gamma == 0)  {
        opserr << "HHTExplicit_TP::newStep() - error in variable\n";
        opserr << "gamma = " << gamma << endln;
        return -1;
    }
    
    deltaT = _deltaT;
    if (deltaT <= 0.0)  {
        opserr << "HHTExplicit_TP::newStep() - error in variable\n";
        opserr << "dT = " << deltaT << endln;
        return -2;
    }
    
    // get a pointer to the LinearSOE and the AnalysisModel
    LinearSOE *theLinSOE = this->getLinearSOE();
    AnalysisModel *theModel = this->getAnalysisModel();
    if (theLinSOE == 0 || theModel == 0)  {
        opserr << "WARNING HHTExplicit_TP::newStep() - ";
        opserr << "no LinearSOE or AnalysisModel has been set\n";
        return -3;
    }
    
    // set the constants
    c2 = gamma*deltaT;
    c3 = 1.0;
    
    if (U == 0)  {
        opserr << "HHTExplicit_TP::newStep() - domainChange() failed or hasn't been called\n";
        return -4;
    }
    
    // set weighting factors for subsequent iterations
    alphaD = alphaR = alphaP = alpha;
    
    // set response at t to be that at t+deltaT of previous step
    (*Ut) = *U;
    (*Utdot) = *Udot;
    (*Utdotdot) = *Udotdot;
    
    // determine new displacements and velocities at time t+deltaT
    U->addVector(1.0, *Utdot, deltaT);
    double a1 = 0.5*deltaT*deltaT;
    U->addVector(1.0, *Utdotdot, a1);
    
    double a2 = deltaT*(1.0 - gamma);
    Udot->addVector(1.0, *Utdotdot, a2);
    
    // no need to zero accelerations because alphaM = 0
    //Udotdot->Zero();
    //theModel->setResponse(*U, *Udot, *Udotdot);
    
    // set the trial response quantities
    theModel->setDisp(*U);
    theModel->setVel(*Udot);