Ribs in Advance Design - Case Study

 

This case study focuses on using the Ribs design function for conducting analysis by considering linear elements as ribs.

 

Example 1: When the ribs element has B1 ≠ B2 ≠ 0:

Ribs design option in Advance Design

Ribs design option in Advance Design

 

In this scenario, the Ribs design option plays a significant role in determining whether beams should be treated as ribs of the slab. When the option is enabled, beams are considered ribs, while disabling the option excludes beams from being treated as ribs of the slab.

 

Effective flange width parameters

Effective flange width parameters

 

 

To begin, the distances B1(b1) and B2(b2) need to be manually inputted in the Ribs-Effective width dialog:

 

Effective width- Ribs dialog

Effective width- Ribs dialog

 

 

Once the FEM+RC design is completed, open the Effective Width dialog to examine the values of Beff1 and Beff2.

 

Ribs characteristics

Ribs characteristics

 

 

These values can be obtained using the following formula:

NOTE: l0 refers to the distance that varies based on the span type. For rib elements with a single span,  l0 is equal to the span between the two axes.

 

Effective flange width parameters

Effective flange width parameters

 

 

 

In this case, the manual calculation is as follows:

Beff,1 = 0.2 x 1.85 + 0.1 x 6 = 0.97m ≤ 1.20m
             0.97m ≤ 1.85m
Beff,2 = 0.2 x 2.85 + 0.1 x 6.0 = 1.17m
             1.17m ≤ 2.85m

 

Example 2: When the rib element has B1 ≠ 0 and B2 = 0:

In this case, the Ribs design option is still relevant, with B1 representing the distance in the 'Y-' direction and B2 being 0.

 

Ribs design - Properties

Ribs design - Properties

 

 

B1=(6.00m-0.30m)/2=2.85m
B2=0

 

Effective width- Ribs dialog

Effective width- Ribs dialog

 

After completing the FEM+RC design, refer to the Effective Width dialog to observe the values of Beff1 and Beff2, obtained through the same calculation formula mentioned earlier.

 

 

Ribs characteristics

Ribs characteristics

 

For Span1:
Beff,1 = 0.2 x 2.85m + 0.1 x (0.85 x 4m) = 0.91m ≤ 0.68m
0.68m ≤ 2.85m

For Span2:
Beff,1 = 0.2 x 2.85m + 0.1 x (0.85 x 6m) = 1.08m ≤ 1.02m
1.02m ≤ 2.85m

 

These calculations demonstrate the effective widths of the rib elements in each scenario.

 

 

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