Earthquake Code Statement (3.6.2.4)

B3 is the Discontinuity of the Vertical Elements of the Structural System, where the vertical elements of the carrier system (columns or curtains) are lifted on some floors and placed on the top or end of the beams or gusset columns, or the curtains on the upper floor are placed on the lower columns ( Figure 3.4 ).

Open

According to Article 3.6.2.4 of TBDY , the following items are valid for B3 type irregularity conditions.

• Columns are never permitted to be placed on the cantilever beams on any floor of the building or on the gussets formed in the columns below.

• If the column rests on a supported beam at both ends, it is sufficient to make a vertical earthquake calculation according to 4.4.3 .

• The curtain on the upper floors is never allowed to rest on the columns below.

• It is never permitted to sit the curtains on any floor of the building, on the beams in their own plane, in the middle of the opening.

In ideCAD Static, it is possible to define columns on cantilever beams or gussets formed in columns on any floor, defining curtains on columns or defining curtains to the middle of the span on the beams. However, when this definition is made, B3 type irregularity is created and it is a definition that does not comply with the Article 3.6.2.4 of TBDY . This modeling technique is under user control but should not be done.

Columns can be defined on any supported beam in ideCAD Statics. However , when this definition is made according to Article 3.6.2.4 (b) of TBDY , the vertical earthquake calculation should be made according to 4.4.3 .
(See: Vertical Seismic Response Spectrum Analysis (4.4.3.1))