AISC 360-10 Members (14th, 2010)

AISC 360-10 (14th, 2010) - an American national standard "Specification for Structural Steel Buildings" released in June 22, 2010. Checks are performed according to the provisions for the load and resistance factor design (LRFD)and Allowable Strength Design (ASD).

This Standard implements checks for the design of members for tension, compression (Chapter D and E including Torsional and Flexural-Torsional Buckling), bending (Chapter F), shear (Chapter G) and combined (Chapter H) and support double symmetric I-beams, single symmetric Channels, Circular, double symmetric Rectangular tubes, Circular and Rectangular bars.

To add AISC 360-10 standard execute StandardANSI/AISC 360-10 - AISC 360-10 Members (14th, 2010) from the main menu. Alternatively, use the Standard context menu:

Standard_AISC Members

To see what elements are not verified for all checks or bending checks according to AISC 360-10 press Preview Not Supported.

It is possible to check the design according to the load and resistance factor design (LRFD) or Allowable strength design (ASD). The difference between these 2 designs is in the load combinations and resistance factors:

According to the standard Design Strength is multiplied on LRFD factor and divided on ASD factor for tensile yielding in the gross section:

In SDC Verifier multiplication is always used. ASD factor are converted to 1 / Sf (ASD). For example, a tensile resistance factor (F_t) = 1 / 1.67 = 0.6.

Press Define to set Section Build Type (rolled or built-up).

Press Define to set Cb (lateral-torsional buckling modification factor):

where

Mmax = absolute value of maximum moment in the unbraced segment, kip-in. (N-mm)
MA = absolute value of a moment at a quarter point of the unbraced segment, kip-in. (N-mm)
MB = absolute value of a moment at a centerline of the unbraced segment, kip-in.(N-mm)
MC = absolute value of a moment at three-quarter point of the unbraced segment, kip-in. (N-mm)

For cantilevers or overhangs where the free end is unbraced, C b = 1.0.

Note: For the doubly symmetric members with no transverse loading between the brace points, Equation F1-1 reduces to 1.0 for the case of equal end moments of the opposite sign (uniform moment), 2.27 for the case of equal end moments of the same sign (reverse curvature bending), and to 1.67 when one end moment equals zero. For singly symmetric members, a more detailed analysis for Cb is presented in the Standard Commentary.

For Shear Check for webs with the transverse stiffeners it is required to define a clear distance between the transverse stiffeners (Chapter G2.1):

Standard_AISC_shear_check

If members are recognized stiffener distance is set to the members length from torsional direction.

According to the calculation procedure, Beam Length for Y and Z direction is required. Data from Beam Member Finders is used automatically:

If beam members are not recognized press .

Formulas of AISC 360-10 standard use Yield and Tensile Stresses from materials. Standard checks if the values are defined for all materials:

Standard checks, in case if all Yield Stress is not equal to zero, Y and Z Offsets for C and T sections and Warping are evaluated:

If count > 0 then press to edit Yield Stress:

It possible to use AISC 360-10 in combination with API 2A RP (1st, 1993) standard. Set option Use API 2A RP for tubular shapes checked to use the standard for circular tubes, press to define settings.

It is possible to take into account second order effects (see explanation in AISC 360-10, Appendix 8):

To include a Torsion check set option Include Torsion check ON.

For torsion the check warping is neglected and if Utilization Factor for torsion exceeds 0.3, the warning code 1234 is set to UF. Additional assessment for torsion is required:

SDC Verifier covers only symmetric and double symmetric shapes. In case your model contains non-symmetric I-beams, Channels, Rectangular tubes press to automatically map them with symmetric shapes.

When all settings are defined, press OK to create standard.

Standard_AISC_material_char

The Standard contains 17 checks: 1 - beam member characteristics, 2-6 - calculation dimensions and factors for 6 shapes, 7-11 - axial/shear/bending Strength, 12 - Tension and Compression check, 13 -Bending Check, 14 - Shear Check, 15- Torsion Check, 16 - All Checks together with the combined.

To verify the model create table for Overall Check:

Standard_AISC_overall_check

All Checks have Utilization Factor parameter = (Force, Moment, etc.) / Design Strength. It should be below one (<1) then the check passes.

The value 12345678 is used when the calculations cannot be performed due to geometrical limitations or calculations are out of scope.

Note: Elastic Section Modulus (S) is calculated using a moment of inertia. Fillets are ignored and to get more accurate results a moment of inertia should be adjusted. Plastic Section Modulus is counted ignoring fillets which in results gives ~1-2% difference.

In Shear Check for circular tube equation G6-2a is not used, because it is not possible to define Lv automatically - distance from maximum to zero shear force. It cannot be defined by user as it is different for each individual load.

The Nominal Shear Strength for the circular tubes equals Minimum of G6-2b and Shear Yielding (0.6 * Fy)

but shall not exceed 0.6 Fy

Note: The shear buckling equations, Equation G6-2a and G6-2b, will control D/t over 100, high-strength steels, and long lengths. For the standard sections, shear yielding will usually take control.