Steel Design

• Design procedures in accordance with 15th Edition AISC Steel Construction Manual and 2016 Specification for Structural Steel Buildings (ANSI/AISC 360-16) provisions for Allowable Stress Design (ASD).

• Section dimensions and properties of steel shapes are USCS values given by AISC Shapes Database.

• ASTM material specifications given by AISC Steel Construction Manual Table 2-4.

  • All W shapes are designed using ASTM A992.

  • The modulus of elasticity () for all steel members is equal to 29,000 ksi.

• Lateral-torsional buckling modification factor () conservatively taken equal to 1.0 and cannot be modified in software.

• Stiffeners, doubler plates, and/or beam bearing plates are not considered for design.

• All user input loads are assumed to be applied from above to the top flange or through shear center of the member.

• The length of bearing (ℓ) for point loads is equal to 3.25 in., unless noted otherwise.

• Deflection analysis considers applied loads and the nominal weight of a member.

  • Shear deflection and deflection due to long-term loading (e.g. creep) are not considered.

• The allowable flexural strength (Mn/Ωb) is determined in accordance with ANSI/AISC 360-16 Chapter F. For all provisions of ANSI/AISC 260-16 Chapter F, the value of Ωb = 1.67.

• The allowable shear strength (Vn/Ωv) is determined in accordance with ANSI/AISC 360-16 Chapter G. For Section G2.1(a), the value of Ωv = 1.50. For all other provisions of Chapter G, Ωv = 1.67.

The applicability of the limit states for flanges and webs with concentrated forces is given in the table below.

[1] Flange local bending applies to only tensile concentrated forces (e.g. negative point load, uplift at support).

[2] Web local crippling applies to only compressive concentrated forces.

[3] Web sideways buckling applies to only compressive concentrated forces where relative lateral movement between the loaded compression flange and the tension flange is not restrained.

[4] Web compression buckling applies to only a pair of compressive concentrated forces (e.g. point load over support).

• Design procedures in accordance with 11th Edition CISC Handbook of Steel Construction and 8th Edition CSA S16 Design of Steel Structures (CAN/CSAS16-14) provisions for Limit States Design (LSD).

• Section dimensions and properties of steel shapes are SI values given by AISC Shapes Database.

• ASTM material specifications given by CISC Handbook of Steel Construction Table 6-7 and Table 6-8.

  • All W shapes are designed using ASTM A992. This grade was chosen since the CISC Handbook of Steel Construction Table 6-8 refers to A992 as the “grade preferred for relative availability” for W sections. Steel shapes in CISC Handbook of Steel Construction refer to ASTM A6/A6M which in turn details A992 for use in building framing.

  • In terms of strength comparisons, CAN/CSA G40.21-04 350W grade of steel has an Fy = 350MPa, whereas the Fy = 345MPa for ASTM A992. Therefore, A992 should give a (slightly) conservative result.

  • The modulus of elasticity () for all steel members is equal to 200,00 MPa.

  • The shear modulus of elasticity () for all steel members is equal to 77,000 MPa.

  • The coefficient of linear expansion () for all steel members is equal to 0.00117 per 100°C change in temperature.

• In lieu of a more accurate analysis, Mu was determined using ω=1.0 with effective unbraced beam length equal to 1.2L for simply supported ends and 1.4L for segments with any other flexural end restraint.

• Stiffeners, doubler plates, and/or beam bearing plates are not considered for design.

• All user input loads are assumed to be applied from above to the top flange or through shear center of the member.

• The length of bearing (ℓ) for point loads is equal to 82.55 mm (3.25 in.), unless noted otherwise.

• Deflection analysis considers applied loads and the nominal weight of a member.

  • Shear deflection and deflection due to long-term loading (e.g. creep) are not considered.

The applicability of the limit states for flanges and webs with concentrated forces is given in the table below.

[1] Flange local bending applies to only tensile concentrated forces (e.g. uplift at support, negative point load).

[2] Web local crippling applies to only compressive concentrated forces.

[3] Web compression buckling applies to only a pair of compressive concentrated forces (e.g. point load over support).

* Weyerhaeuser software shall return a warning message if point load located at ≤.