# ANSI/AISC 360-10

ANSI/AISC 360-10 - 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).

https://www.aisc.org/WorkArea/showcontent.aspx?id=41132

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).

Note: Tension, Compression and Shear checks are performed for 6 section types: circular tubes, rectangular tubes, I, C, L and T shapes. Bending and Combined checks are performed for: Double Symmetric I beams, circular tubes and rectangular tubes.

To add ANSI/AISC 360-10 standard execute

– from the main menu. Alternatively use context menu:To see what elements are not verified for all checks or bending checks according to AISC 360-10 press

.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

to set (rolled or built-up).Press Define to set Cb (lateral-torsional buckling modification factor):

where

M_{max} | = absolute value of maximum moment in the unbraced segment, kip-in. (N-mm) | |

M_{A} | = absolute value of a moment at a quarter point of the unbraced segment, kip-in. (N-mm) | |

M_{B} | = absolute value of a moment at a centerline of the unbraced segment, kip-in.(N-mm) | |

M_{C} | = 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.

User 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 C* _{b}* is presented in the Standard Commentary.

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

Formulas of ANSI/AISC 360-10 standard use Yield Stress from materials, Warping Constant and Y and Z Neutral Axis Offset. It is important to set this value for each material/property.

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:

Press to evaluate Offsets and Warping Constants in Femap and update in SDC Verifier.

Loads for Tables/Plots - creates standard tables and plots for Axial, Bending, Shear and Overall Checks for selected Loads:

When all settings are defined, press

to create standard.Standard contains 17 checks: 1 - beam member characteristics, 2-7 - calculation dimensions and factors for 6 shapes, 8-11 - Bending for Double Symmetric I beams, 12 - additional calculations for the compression, 13 - Tension and Compression check, 14 -Bending Check, 15-16 - Shear Check, 17 - All Checks together with the combined.

To verify the model create table for Overall Check:

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

Note: Elastic Section Modulus (S) is calculated using a moment of inertia. In Femap 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% error.

In Shear Check for circular tube equation G6-2a is not used, because it is not possible to define L_{v} 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 * F_{y})

but shall not exceed 0.6 F_{y}

User 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 make control.