E-TN-CBD-AISC-LRFD360-05-010

Bending and Deflection Checks Page 1 of 2

This Technical Note describes how the program checks bending and deflection for AISC-LRFD 360-05 design.

Bending Check Locations

For each design load combination the program checks bending at the follow-ing locations:

? Point of maximum moment for the design load combination considered.

? Point load locations for the design load combination considered.

Bending Check at Point of Maximum Moment

For beams with no axial load, or when axial loads are not considered, the program uses Equation 1 to perform bending checks for both composite and noncomposite beams. If there is axial load to be considered, the interaction formulas described in Composite Beam Design AISC-LRFD 360-05 Technical Note Moment Capacity for Steel Section Alone are used rather than Equation 1.

u

n

M 1.0M φ≤ Eqn. 1

where,

Mu = The maximum required flexural strength, that is, the maximum

applied factored moment, kip-in.

Mn = Moment capacity for full composite connection or partial com-

posite connection, as applicable, kip-in.

φ = Resistance factor for bending, unitless. For positive bending in a

composite beam with an assumed plastic stress distribution,

Composite Beam Design AISC-LRFD 360-05 Bending and Deflection Checks φbcpp is used. For negative bending in a composite beam with an

assumed plastic stress distribution, φbcnp is used. For positive

bending in a composite beam with an assumed elastic stress

distribution, φbcpe is used. For negative bending in a composite

beam with an assumed elastic stress distribution, φbcne is used.

If the beam is specified to be noncomposite, φb is used.

If there is axial load to be considered, the interaction formulas described in Composite Beam Design AISC-LRFD 360-05 Technical Note Moment Capacity for Steel Section Alone are used rather than Equation 1.

Bending Check at Point Loads

The bending check at point load locations is performed by applying Equation 9 in Composite Beam Design AISC-LRFD 360-05 Technical Note Shear Connec-tors at the point load location. See the next section entitled "Bending Checks" for additional information.

Deflection Check

Deflection is calculated as described in Composite Beam Design Technical Note Beam Deflection and Camber. For full composite connection I tr is used in the deflection calculations. For partial composite connection I eff is used in the deflection calculations.

Bending and Deflection Checks Page 2 of 2