Before proceeding with the modelling of the transfer beam, it is important to understand how the physical model translate to an analytical model when building analysis is performed.

• The physical model is what you see on the modelling screen where all members are rendered in 3D according to the actual sizes
  
• The analytical model is a wire-frame model that is created by solver which is actually what is analyzed finally.
  
• The analytical model can be viewed by clicking Analytical Model in Analysis tab. 
  

Do not use FE Floor Analysis Chasedown for the analysis and design of transfer beam as it is beyond the scope of FE Floor Analysis. Always run Building Analysis. 

For more explanation refer :  Modelling, Analysis & Design Flowchart

Physical Model Versus Analytical Model

In ProtaStructure, we can visualize all members as single line wire-frame created along the axis or axes intersection:

• A column will be a single line wire frame at the intersection of 2 axes.

               Physical Model                                                Analytical Model

• A beam is a single wire-frame line along the insertion axis. Hence for the column and beam members to connect properly, they need to meet at the exact axes’ intersection.

      Physical Model                                            Analytical Model

When modelling a discontinuous column supported by a transfer beam, the column should use the same longitudinal axis as the beam to be supported.  In the example below :

1. The transfer beam is modeled using axis 1
   
2. The upper column is inserted using intersection of axis 1 & C
   
3. The lower column is inserted using intersection of axis 2 & D

When viewing the plan view transfer storey, it's useful to switch on "Display Transfer Columns and Walls on Plan" via Visual Interrogation to show the discontinuous columns above the transfer storey. As shown above, the discontinuous columns are shown in a different color (blue) on the plan view of ST01.

For more information you can refer :  How to show transfer (discontinuous) columns and Walls on Plan view

After the analysis, the Model and Analysis Results Display clearly shows only the upper column is supported as it inserted using the same Axis 1 as the transfer beam.

Transfer Columns with auto Rigid Links

In example model below, transfer column S1 is using the same insertion axis 1 as the beam.  Transfer column S2 is inserted using a different offset axis 2.  

A comparison is done with analysis done with "Transfer Member" unchecked and checked (as shown below). 

After the analysis, the Analytical model clearly shows the lower column S2 is now supported by the transfer beam via a rigid beam.  

The rigid beam is rendered as dark blue line.  The eccentric forces of the offset column will be considered, e.g. there will be additional torsion on the transfer beam due to this offset.

Support Offset Transfer Column with Dummy Beam

1. Click Beam element icon
   
2. Connect the dummy beam from the transfer beam axis to insertion axis of the discontinuous column
   
3. The dummy beams may be of any size and will be considered as rigid links to connect the transfer beam and the eccentric discontinuous column.

After the analysis, recheck the Analytical Model, which shows the lower column is now supported by the transfer beam (via a rigid beam) :

Transfer Beam Supporting Discontinuous Wall

A wall is a single plane along the longitudinal insertion axis. Therefore, for a discontinuous wall to be supported by the beam, both the beam and wall members must share the same longitudinal axis. 

                                                          Physical Model                                  

1. As shown in the Analytical Model above, the Mid-Pier assumption will be unrealistic or unreasonable as the transfer wall will exert a point load in the middle of the wall.  This inaccuracy will worsen with longer transfer wall. 
2. The FE Shell model will give an accurate & realistic result as the transfer wall loading on beam approximate that of a uniform load; as each shell will exert a separate load on the transfer beam. 

Do not use Wall Model Type as "Mid-Pier wall" for transfer wall. This is because Mid-Pier will transfer the load as a single point load on the transfer beam, which is inaccurate. 

Supporting Offset Discontinuous Wall with Dummy Beams

If the transfer wall is not using the same longitudinal insertion axis as the transfer beam below, it will not be supported, even if "Transfer Member" is checked in wall properties (unlike similar situation for transfer column). 

In such cases, dummy beams must be manually created to connect both ends of the wall to the transfer beam insertion axis.  The steps are : 

• Create ghost axes for the dummy beams.
  
• Connect the dummy beam from the transfer beam axis to the axis of the transfer wall.
  
• Ensure that appropriate intersection points are available for the creation of the wall and beam elements.
  
• The dummy beams may be of any size and will be considered as rigid links to induce the appropriate forces onto the transfer beam.

As shown in the example model above, the dummy beams will be converted to rigid link during the analysis and will result in :

1. The load transferred from the discontinuous walls to the transfer beam
   
2. Induced torsional moment to the transfer beam

Moment of Transfer Beam Supporting Wall