protected override TCIterationBound GetSolutionBoundaries(SectionAnalysisResult result,
LinearStrainDistribution ApproximationStrainDistribution)
{
double prestressForce = this.GetPrestressForceEffective();
if (prestressForce == 0)
{
//TODO: add check for prstressing if needed
//throw new NotPrestressedBeamException();
}
//prestressed beam strain iteration is different (from regular RC) from regular concrete because we are assuming that
//the maximum depth of compression zone is 0.6d. Therefore this determines the start of iterations
TCIterationBound bound = new TCIterationBound();
switch (currentCompressionFiberPosition)
{
case FlexuralCompressionFiberPosition.Top:
bound.MinStrain = ApproximationStrainDistribution.BottomFiberStrain;
break;
case FlexuralCompressionFiberPosition.Bottom:
bound.MinStrain = ApproximationStrainDistribution.TopFiberStrain;
break;
default:
throw new CompressionFiberPositionException();
}
bound.MaxStrain = CalculateMaximumSteelStrain(currentCompressionFiberPosition);
return(bound);
}
protected virtual TCIterationBound GetSolutionBoundaries(SectionAnalysisResult result, LinearStrainDistribution ApproximationStrainDistribution)
{
double t = Math.Abs(result.TForce);
double c = Math.Abs(result.CForce);
SectionAnalysisResult secondResult = new SectionAnalysisResult();
TCIterationBound data = new TCIterationBound();
LinearStrainDistribution secondApproximationStrainDistribution = null;
double MaxSteelStrain = CalculateMaximumSteelStrain(currentCompressionFiberPosition);
//Step 1: create adjusted strain distribution
if (t > c)
{
if (currentCompressionFiberPosition == FlexuralCompressionFiberPosition.Top)
{
secondApproximationStrainDistribution = new LinearStrainDistribution(ApproximationStrainDistribution.Height,
ApproximationStrainDistribution.TopFiberStrain, this.MaxConcreteStrain);
}
else
{
secondApproximationStrainDistribution = new LinearStrainDistribution(ApproximationStrainDistribution.Height,
this.MaxConcreteStrain, ApproximationStrainDistribution.BottomFiberStrain);
}
}
else
{
if (currentCompressionFiberPosition == FlexuralCompressionFiberPosition.Top)
{
secondApproximationStrainDistribution = new LinearStrainDistribution(ApproximationStrainDistribution.Height,
ApproximationStrainDistribution.TopFiberStrain, MaxSteelStrain);
}
else
{
secondApproximationStrainDistribution = new LinearStrainDistribution(ApproximationStrainDistribution.Height,
MaxSteelStrain, ApproximationStrainDistribution.BottomFiberStrain);
}
}
//Step 2: Fill in data for output
if (currentCompressionFiberPosition == FlexuralCompressionFiberPosition.Top)
{
data.MinStrain = -Math.Max(Math.Abs(ApproximationStrainDistribution.BottomFiberStrain), Math.Abs(secondApproximationStrainDistribution.BottomFiberStrain));
data.MaxStrain = -Math.Min(Math.Abs(ApproximationStrainDistribution.BottomFiberStrain), Math.Abs(secondApproximationStrainDistribution.BottomFiberStrain));
}
else
{
data.MinStrain = -Math.Max(Math.Abs(ApproximationStrainDistribution.TopFiberStrain), Math.Abs(secondApproximationStrainDistribution.TopFiberStrain));
data.MaxStrain = -Math.Min(Math.Abs(ApproximationStrainDistribution.TopFiberStrain), Math.Abs(secondApproximationStrainDistribution.TopFiberStrain));
}
return(data);
}
protected virtual SectionAnalysisResult FindPureMomentResult(FlexuralCompressionFiberPosition CompressionFiberPosition,
TCIterationBound bound, double StrainConvergenceTolerance = 0.00001)
{
currentCompressionFiberPosition = CompressionFiberPosition; //store this off because it will be necessary during iteration
StrainHeight = GetStrainDistributionHeight(CompressionFiberPosition); //store this off because it will be necessary during iteration
double SteelStrain = 0;
double StrainMax = bound.MaxStrain;
double StrainMin = bound.MinStrain;
double targetTCDelta = 0;
LinearStrainDistribution finalStrainDistribution = null;
//SteelStrain = RootFinding.Brent(new FunctionOfOneVariable(GetTandCDeltaForSteelStrainIteration), TCDeltaMin, TCDeltaMax, StrainConvergenceTolerance, targetTCDelta);
SteelStrain = RootFinding.Brent(new FunctionOfOneVariable(DeltaTCCalculationFunction), StrainMin, StrainMax, StrainConvergenceTolerance, targetTCDelta);
switch (CompressionFiberPosition)
{
case FlexuralCompressionFiberPosition.Top:
finalStrainDistribution = new LinearStrainDistribution(StrainHeight, this.MaxConcreteStrain, SteelStrain);
break;
case FlexuralCompressionFiberPosition.Bottom:
finalStrainDistribution = new LinearStrainDistribution(StrainHeight, SteelStrain, this.MaxConcreteStrain);
break;
default:
throw new CompressionFiberPositionException();
}
SectionAnalysisResult finalResult = GetSectionResult(finalStrainDistribution, CompressionFiberPosition);
return(finalResult);
}
public IStrainCompatibilityAnalysisResult GetNominalFlexuralCapacity
(FlexuralCompressionFiberPosition CompressionFiberPosition)
{
currentCompressionFiberPosition = CompressionFiberPosition;
//Step 1: Assume strain distribution with all bars below section centroid yielding
LinearStrainDistribution TrialStrainDistribution = GetInitialStrainEstimate(CompressionFiberPosition);
SectionAnalysisResult TrialSectionResult = GetSectionResult(TrialStrainDistribution, CompressionFiberPosition);
double Mn = 0;
//check id T and C force are equal
//if T<>C
if (GetAnalysisResultConverged(TrialSectionResult, ConvergenceToleranceStrain) == false)
{
SectionAnalysisResult IteratedResult = null;
try
{
TCIterationBound bound = GetSolutionBoundaries(TrialSectionResult, TrialStrainDistribution); //make sure solution exists
IteratedResult = FindPureMomentResult(CompressionFiberPosition, bound, ConvergenceToleranceStrain);
RebarPointResult controllingBar = GetMaxSteelStrainPoint(TrialSectionResult.TensionRebarResults);
Mn = IteratedResult.Moment;
return(new ConcreteSectionFlexuralAnalysisResult(Mn, IteratedResult.StrainDistribution, controllingBar));
}
catch (SectionAnalysisFailedToConvergeException)
{
throw new SectionFailedToConvergeException();
}
}
//if T=C
else
{
IStrainCompatibilityAnalysisResult result = GetResult(TrialSectionResult);
return(result);
}
}