Method newStep

SRC/analysis/integrator/HHTHSFixedNumIter.cpp:169–230

int HHTHSFixedNumIter::newStep(double _deltaT)
{
    deltaT = _deltaT;
    if (beta == 0 || gamma == 0 )  {
        opserr << "HHTHSFixedNumIter::newStep() - error in variable\n";
        opserr << "gamma = " << gamma << " beta = " << beta << endln;
        return -1;
    }
    
    if (deltaT <= 0.0)  {
        opserr << "HHTHSFixedNumIter::newStep() - error in variable\n";
        opserr << "dT = " << deltaT << endln;
        return -2;
    }
    
    // get a pointer to the AnalysisModel
    AnalysisModel *theModel = this->getAnalysisModel();
    
    // set the constants
    c1 = 1.0;
    c2 = gamma/(beta*deltaT);
    c3 = 1.0/(beta*deltaT*deltaT);
    
    if (U == 0)  {
        opserr << "HHTHSFixedNumIter::newStep() - domainChange() failed or hasn't been called\n";
        return -3;
    }
    
    // set response at t to be that at t+deltaT of previous step
    (*Utm2) = *Utm1;
    (*Utm1) = *Ut;
    (*Ut) = *U;
    (*Utdot) = *Udot;
    (*Utdotdot) = *Udotdot;
    
    // determine new velocities and accelerations at t+deltaT
    double a1 = (1.0 - gamma/beta);
    double a2 = deltaT*(1.0 - 0.5*gamma/beta);
    Udot->addVector(a1, *Utdotdot, a2);
    
    double a3 = -1.0/(beta*deltaT);
    double a4 = 1.0 - 0.5/beta;
    Udotdot->addVector(a4, *Utdot, a3);
    
    // determine the velocities and accelerations at t+alpha*deltaT
    (*Ualphadot) = *Utdot;
    Ualphadot->addVector((1.0-alphaF), *Udot, alphaF);
    
    (*Ualphadotdot) = *Utdotdot;
    Ualphadotdot->addVector((1.0-alphaI), *Udotdot, alphaI);
    
    // set the trial response quantities
    theModel->setVel(*Ualphadot);
    theModel->setAccel(*Ualphadotdot);
    
    // increment the time to t+alpha*deltaT and apply the load
    double time = theModel->getCurrentDomainTime();
    time += alphaF*deltaT;