internal double RhsStressInteractionQf(HssPlateOrientation PlateOrientation)
        {
            double Qf   = 0.0;
            double Beta = GetBeta();

            if (IsTensionHss == false)
            {
                if (PlateOrientation == HssPlateOrientation.Transverse)
                {
                    //(K1-16)
                    Qf = 1.3 - 0.4 * U / Beta;
                    Qf = Qf < 1.0 ? Qf : 1.0;
                }
                else
                {
                    //(K1-17)
                    Qf = Math.Sqrt(1.0 - Math.Pow(U, 2));
                }
            }
            else
            {
                Qf = 1.0;
            }
            return(Qf);
        }
        internal double RhsStressInteractionQf(HssPlateOrientation PlateOrientation)
        {

            double Qf = 0.0;
            double Beta = GetBeta();

            if (IsTensionHss == false)
            {
                if (PlateOrientation == HssPlateOrientation.Transverse)
                {
                    //(K1-16)
                    Qf = 1.3 - 0.4 * U / Beta;
                    Qf = Qf < 1.0 ? Qf : 1.0;
                }
                else
                {
                    //(K1-17)
                    Qf = Math.Sqrt(1.0 - Math.Pow(U, 2));
                } 
            }
            else
            {
                Qf = 1.0;
            }
            return Qf;
        }