5.7design procedure

Step 1. Choose trial values for the beam sections, column sections, and RBS dimensions $a, b$, and $c$ (Figure 5.1) subject to the following limits:

where

• $\begin{aligned} a & =\text { horizontal distance from face of column flange to start of an RBS cut, } \\ & \text { in. (mm) }\end{aligned}$

$b \quad$ = length of RBS cut, in. (mm)

$b_{b f}=$ width of beam flange, in. (mm)

• $c \quad$ = depth of cut at center of reduced beam section, in. (mm)
• $d \quad=$ depth of beam, in. (mm)

Confirm that the beams and columns are adequate for all load combinations specified by the applicable building code, including the reduced section of the beam, and that the design story drift for the frame complies with applicable limits specified by the applicable building code. Calculation of elastic drift shall consider the effect of the reduced beam section. In lieu of more detailed calculations, effective elastic drifts may be calculated by multiplying elastic drifts based on gross beam sections by 1.1 for flange reductions up to 50% of the beam flange width. Linear interpolation may be used for lesser values of beam width reduction.

Step 2. Compute the plastic section modulus at the center of the reduced beam section, $Z_{R B S}$ :

(5.7-4)

where

$\begin{aligned} Z_{b} & =\text { plastic section modulus of beam, in. }^{3}\left(\mathrm{~mm}^{3}\right) \\ t_{b f} & =\text { thickness of beam flange, in. (mm) }\end{aligned}$

Step 3. Compute the probable maximum moment at the plastic hinge, $M_{p r}$, in accordance with Section 2.4.3, where $Z_{e}=Z_{R B S}$.

Step 4. Compute the distance of the plastic hinge from the face of the column, $S_{h}$ :

(5.7-5)

Step 5. Compute the shear force at the plastic hinge, $V_{h}$, in accordance with Section 2.4.4.

Step 6. Compute the probable maximum moment at the face of the column, $M_{f}$, in accordance with Section 2.4.5.

Step 7. Compute the plastic moment of the beam based on the expected yield stress, $M_{p e}$ :

(5.7-6)

where $F_{y} =$ specified minimum yield stress, ksi (MPa) $R_{y} =$ ratio of expected yield stress to specified minimum yield stress

Step 8. Check the flexural strength of the beam at the face of the column:

(5.7-7)

If Equation 5.7-7 is not satisfied, adjust the values of $c, a$, and $b$, or adjust the section size, and repeat Steps 2 through 8.

Step 9. Check the design shear strength of the beam in accordance with the AISC Specification.

The required shear strength of the beam shall be determined in accordance with Section 2.5.

Step 10. Design the beam web-to-column connection in accordance with Section 5.5.

The required shear strength of the beam web-to-column connection shall be taken equal to the required shear strength of the beam.

Step 11. Check continuity plate requirements in accordance with Section 2.6.

Step 12. Check the panel zone in accordance with Section 2.7.

Step 13. Check the column-beam moment ratio in accordance with Section 2.8.