public NodalDisplacement DetermineRigidbodyPointDisplacement(Point2D coordinate, LoadPattern loadPattern)
{
LateralLevelForce forceAtLoadPattern = Forces.First(f => f.LoadPattern == loadPattern);
var alpha = new Unitless((coordinate - LateralLevel.CenterOfRigidity).SignedAngleTo(Vector2D.XAxis));
var d = new Length(coordinate.DistanceTo(LateralLevel.CenterOfRigidity), LengthUnit.Inch);
Moment M = forceAtLoadPattern.TotalT(LateralLevel.CenterOfRigidity);
var rotation = (Unitless)(M / LevelStiffness.J);
Length displacementX = (Length)(forceAtLoadPattern.DirectX / LevelStiffness.X + d * rotation * Result.Sin(alpha));
Length displacementY = (Length)(forceAtLoadPattern.DirectY / LevelStiffness.Y + d * rotation * Result.Cos(alpha));
if (LoadPatternTypeConverter.Convert(loadPattern) == LoadPatternType.Earthquake)
{
displacementX = (Length)(displacementX * Cd);
displacementY = (Length)(displacementY * Cd);
}
return(new NodalDisplacement
{
LoadPattern = loadPattern,
Ux = displacementX.ConvertTo(LengthUnit.Inch),
Uy = displacementY.ConvertTo(LengthUnit.Inch),
Rz = 0
});
}