D1.A.10.6 Updates to AISC 360-16

Section Classification

The width to thickness ratio limits for members in flexure have been updated for the following element types as per AISC 360-16:

Stems of tees (14) are considered slender when $d / t > 1.52 \sqrt{\frac{E}{F_{y}}}$
Flanges of box sections (21) are considered slender when $b / t > 1.49 \sqrt{\frac{E}{F_{y}}}$

CHAPTER E Compression Checks: Torsional & Flexural-Torsional Buckling Calculations

Design for the following profile shapes/conditions have been updated to use the corresponding clauses/equations from AISC 360-16:

2.a Cl. E4: Non-Slender Double Angles & Tee Shapes

Calculation of Fez and Fey to use (E4-9) and (E4-8).
Calculation of Fe to use (E4-3).
Calculation of Fcr to use (E3-2) or (E3-3).
Calculation of Pn to use (E4-1).

2.b Cl. E5: Single-Angle Compression Members

·Flexural torsional buckling limit for single angles changed to $b / t \leq 0.71 \sqrt{\frac{E}{F_{y}}}$ .

2.c Cl. E7: Compression Members with Slender Elements

Calculation of nominal compressive strength and critical stress F_cr updated to follow the updated criteria from Clause E7.

CHAPTER F Flexure Checks

Design for Flexural members has been updated to use the following:

3.a Cl.F4 : Non-Standard(other) I Shaped Members

Lateral Torsional Buckling:

The calculation of effective radius of gyration, r_t , updated to use the AISC 360-16 equation F4-11 for I-shapes with a rectangular compression flange:

r_{t} = \frac{b_{f c}}{\sqrt{12 (1 + \frac{1}{6} a_{w})}}

(F4-11)

3.b Cl.4 : Tension Flange Yielding

The tension flange yielding checks have been updated to use the updated web plastification factor calculations as per equations F4-16a to F4-17.

When I_yc/I_y > 0.23

When

\frac{h_{c}}{t_{w}} \leq λ_{p w}

R_{p t} = \frac{M_{p}}{M_{y t}}

(F4-16a)

When

\frac{h_{c}}{t_{w}} > λ_{p w}

R_{p t} = [\frac{M_{p}}{M_{y t}} - (\frac{M_{p}}{M_{y t}} - 1) (\frac{λ - λ_{p w}}{λ_{r w} - λ_{p w}})] \leq \frac{M_{p}}{M_{y t}}

(F4-16b

When I_yc/I_y ≤ 0.23
R_pt = 1.0 (F4-17)

3.c Cl.F7 : Flexural checks for Square and Rectangular HSS & Box Sections

Cl.F7.2: Flange local buckling checks updated to use F7-4 & F7-5 of AISC 360-16 to calculate the effective width of slender elements.

For HSS

b_{e} = 1.92 t_{f} \sqrt{\frac{E}{F_{y}}} (1 - \frac{0.38}{b / t_{f}} \sqrt{\frac{E}{F_{y}}}) \leq b

(F7-4)

For box sections

b_{e} = 1.92 t_{f} \sqrt{\frac{E}{F_{y}}} (1 - \frac{0.34}{b / t_{f}} \sqrt{\frac{E}{F_{y}}}) \leq b

(F7-5)

Cl.F7.3: Web local buckling checks updated to use F7-6 through to F7-9 of AISC 360-16.

For sections with noncompact webs

M_{n} = M_{p} - (M_{p} - F_{y} S) (0.305 \frac{h}{t_{w}} \sqrt{\frac{F_{y}}{E}} - 0.738) \leq M_{p}

(F7-6)

where

h

=

depth of web, as defined in Section B4.1b, in. (mm)

For sections with slender webs

compression flange yielding
M_n = R_pgF_yS (F7-7)

compression flange local buckling

M_n = R_pgF_crS_xc

(F7-8)

and

F_{c r} = \frac{0.9 E k_{c}}{{(\frac{b}{t_{f}})}^{2}}

(F7-9)

where

R_pg	=	defined by Equation F5-6 with a_w = 2ht_w/(bt_f)
k_c	=	4.0

Cl.F7.4: Lateral torsional buckling checks updated to use F7-6 through to F7-13 of AISC 360-16.

3.d Cl.F9 : Flexural checks for Tees and Double Angles

Yielding checks for Tee sections updated to use Eqn F9-4 of AISC 360-16.
Yielding checks for Double Angle sections updated to use Eqn F9-5 of AISC 360-16.
M_p = 1.5M_y (F9-5)
Lateral torsional buckling checks updated to use Eqns F9-6 through to F9-13 of AISC 360-16
Flange Local Buckling calculations of Tees and double angle legs updated to include criteria as per CL. F9.3 (b) of AISC 360-16
Web local buckling checks for Stem of Tee sections updated to use Cl F9.4 - Eqns F9-17 through to F9-19 of AISC 360-16.
Web local buckling checks for legs of double angle sections updated to use Cl F9.4 (b) of AISC 360-16.

3.e Cl.F10 : Flexural checks for Single Angles

Lateral Torsional Buckling checks updated to use Eqns F10-4 through to F10-5b of AISC 360-16.

CHAPTER G Shear Checks

4.a Cl.G2: I Shapes and Channels

Calculation of Shear strength coefficient Cv updated to use Eqns G2-2 to G2-4 of AISC 360-16
Calculation of Shear buckling coefficient kv updated to use Eqns from section G2 of AISC 360-16.
Criteria for consideration of Tension field action updated as per Section G2.2 of AISC 360-16.
Shear strength calculations for cases with tension field action updated to use Eqns G2-6 through to G2-11 of AISC 360-16