To start the beam design

In STAAD.Pro, ensure you are on the Frame | Design page in the Building Planner mode.

Tip: When you import STAAD.Pro model data into RCDC, grids are automatically detected and assigned. You can manually edit both the exact locations of grids as well as grid labels in RCDC for drawing generation.

In the top-right dialog, check the Level :1 option and then click Design Beams.

RCDC opens and the New Project dialog opens.
Enter the project data and select the design code:
1. Type Tutorial in the Project field.
2. (Optional) Type Client and Engineer name. This information is used as the header for all reports. It will be automatically imported from the STAAD.Pro input file Job Information block if available.
3. Select EN 02 - 2004 from the Design Code drop-down list. This tutorial uses the Eurocode. However, you can select any available code. Just note that some design settings and features may vary based on the code selection made here.
The beam continuity is automatically detected as the analytical model data is read.
Either:

select the General and Reinforcement Settings tool

or
select Settings > General and Reinforcement Settings

The General and Reinforcement Settings dialog opens.
In the Rebar list, clear the check mark by both 32 (mm) and 40 (mm). The initial design will be evaluated using smaller size bars where possible.
Note: All other design settings are left as their defaults, but you can make many design and detailing changes here.
Click OK.

Note: There are numerous other detailing and drawing settings in RCDC that allow you to customize the concrete detailing for your client or organization’s needs. For details on these options, refer to the RCDC help by pressing <F1> or selecting Help > Contents.