private void _calc_service_NA(double modRatio) //calculate neutral axis without axial load
{
this.calcReinf();
double crackedNA = 0;
double compressionDepth = 1;//_radius/2*.8999633;
double targetNA = _radius - compressionDepth;
CircularSegment compressionBlock = new CircularSegment(_radius, compressionDepth);
double increment = 12.321;
while (targetNA != crackedNA)
{
crackedNA = (ReinforcingFirstMoment + (compressionBlock.Area * compressionBlock.CG) / modRatio) / (ReinforcingArea + compressionBlock.Area / modRatio);
if (Math.Round(crackedNA, 6) == Math.Round(targetNA, 6))
{
break;
}
else if (targetNA > crackedNA)
{
compressionDepth += increment;
}
else
{
increment *= 0.5;
compressionDepth -= increment;
}
targetNA = _radius - compressionDepth;
compressionBlock.CompressionDepth = compressionDepth;
}
_cracked_NA = crackedNA;
}
private void _calc_cracked_moment_of_inertia(double modRatio)
{
//_calc_service_NA(modRatio);
CircularSegment compressionBlock = new CircularSegment(_radius, _radius - _cracked_NA);
this.calcReinf();
_cracked_moment_of_inertia = ReinforcingInertia + ReinforcingArea * Math.Pow((_cracked_NA - ReinforcingCG), 2) +
(compressionBlock.Cracked_I + compressionBlock.Area * Math.Pow(_cracked_NA - compressionBlock.CG, 2)) / modRatio;
} //calculate moment of inertia without axial load
private double[,] _concrete_service_terms(double radius, double neutralAxis, double stress, int increments) //calculate total concrete force, moment and CG
{
CircularSegment compressionBlock = new CircularSegment();
compressionBlock.Radius = radius;
double stressIncrement = stress / increments;
double compressionDepthIncrement = (radius - neutralAxis) / increments;
double force = 0;
double firstMoment = 0;
double[,] outputTerms = new double[1, 3];
for (int i = 0; i < increments; i++)
{
compressionBlock.CompressionDepth = (radius - neutralAxis) - compressionDepthIncrement * (i + 0.5);
force += compressionBlock.Area * stressIncrement;
firstMoment += compressionBlock.Area * compressionBlock.CG * stressIncrement;
}
outputTerms[0, 0] = force; //total concrete force
outputTerms[0, 1] = firstMoment / force; // concrete force CG
outputTerms[0, 2] = firstMoment / 12; //total concrete force moment
return(outputTerms);
}
