Calc. No. CALCULATION SHEET Project No. Project Title: Calc. By Date Rev. Subject: Steel beam capacity calculation in accordance with the "Manual of Steel Construction" Load and Resistance Factor Design" (LRFD) Beam Design for Flexure and Lateral-Tortional Buckling. Section properties Braced length Section Lb = 150 in A = in2 beam cross-sectional area Lb - distance between points braced against lateral Iy = in4 moment of inertia about Y axis displacementof the compression flange or between Sx = in3 elastic section modulus - major axis points braced to prevent twist of the cross section. ry = in radius of gyration about minor axis (This parameter can not be mdoified in the Demo Version) J = in4 tortional constant Cw = in6 warping constant Zx = in3 Steel properties E = ksi modulus of elasticity of steel per Manual of Steel Construcion (LRFD) G = ksi shear modulus of elasticity of steel Chapter F Section 2.a Fy = ksi minimum yield stress of the type of steel being used Fyf = ksi yield stress of flange Fyw = ksi yield stress of web Fr = ksi compressive residual stress in flange for rolled shapes Fr = 10 ksi, for welded shapes Fr = 16.5 ksi Cb = bending coefficient dependent upon moment gradient Cb is permitted to be conservatively taken as 1.0 fb = resistance factor for flexure Yielding flexural design strength per Manual of Steel Construcion (LRFD) Mp = Fy * Zx = kip-ft plastic section moment < 1.5 My Chapter F Section 1. 1.5*My = Fy * Sx = kip-ft Mn = Mp = kip-ft fb * Mn = kip-ft Yielding flexural design bending moment Lateral - torsional Buckling per Manual of Steel Construcion (LRFD) Lr - limiting laterally unbraced length Chapter F Lp = 1.76*ry*sqrt(E/Fyf) = in Eq. F1-4 for I shaped members and channels FL = smaller of (Fyf - Fr) or Fyw FL = ksi Mr = FL * Sx = kip-ft Eq. F1-7 X1 = (p/Sx)*sqrt(EGJA/2) = ksi Eq. F1-8 X2 = 4*(Cw/Iy)*(Sx/GJ)2 = ksi-2 Eq. F1-9 Lr = (ry*X1/FL)*sqrt(1+sqrt(1+X2*FL2)) = in Eq. F1-6 for Lb < Lr Chapter F Section 2.a applies Mn = Cb*[Mp-(Mp-Mr)*(Lb-Lp)/(Lr-Lp)] = Eq. F1-2 fb * Mn = for Lb > Lr Chapter F Section 2.b applies Mn = Mcr Mcr = Cb*Sx*X1*sqrt(2)/(Lb/ry)*sqrt(1+X12*X2/(2*(Lb/ry)2) Mcr = fb * Mn = References: Manual of Steel Construction - American Institute of Steel Construction Inc., 2005