Navigation:  Working With Beam Calculations > Concrete Beam Calculations > T-Beam Sections

Concrete beam calculations may be launched with T-Beam geometry IF AND ONLY IF the beam and slab have been joined to each other.  If the beam and slab are not joined, the launched process will behave as described in Rectangular Beam Sections - Unjoined.

 

An example of a concrete beam joined to a slab was previously illustrated in Rectangular Beam Sections - Joined:

 

 

 

When the calculation launch process reaches the "Section Geometry" tab, the user will be informed that the beam IS eligible for design as a T-Beam.  Using the "Select" button on the row marked "Skip" and "No T-Beam" will launch the calculation as a rectangular beam without any Tee geometry.  Clicking the "Select" button of any other row in the table will launch the concrete beam calculation with the T-Beam geometry shown in that row.

 

 

 

As discussed in Rectangular Beam Sections - Joined, the table always includes an option to skip T-Beam behavior.  In addition, the table also displays any T-Beam section geometry detected from the model, as well as an option for the user to manually override the effective width conditions.  The "Side 1" and "Side 2" conditions displayed in the table are computed from physical conditions in the Revit model using the ACI 318 criteria for concrete T-Beam effective width.  In ACI 318-14 and -19, these provisions are displayed in Table 6.3.2.1 "Dimensional limits for effective overhanging flange width for T-beams".

 

In the case of an interior (non edge) beam, the effective width on EACH SIDE is taken as the least of:

 

•8h                8 times the slab thickness (h)

 

•sw / 2        Half the clear distance (sw) to the nearest adjacent beam web

 

•ln / 8                One-eighth of the current clear span (ln)

 

 

In the case of an edge beam, the effective width on ONE SIDE is taken as the least of:

 

•6h                6 times the slab thickness (h)

 

•sw / 2        Half the clear distance (sw) to the nearest adjacent beam web

 

•ln / 12        One-twelfth of the current clear span (n)

 

 

ENERCALC for Revit checks each of these criteria automatically, and the criterion found to control effective width for each respective side is indicated in the "Condition" column.  This includes detecting whether the beam falls at an edge condition, and invoking the applicable ACI criteria accordingly:

 

 

 

When varying conditions are discovered, the user will be presented with multiple geometry conditions to choose from.  The user must assign a single controlling section geometry which will apply to all spans (special note #6 in Concrete Beam Sections).

 

For example, when a multi-span beam has differing clear spans, the table displays a T-Beam geometry line item for each condition found:

 

 

 

 

Similarly, when a beam has varying adjacency conditions, different geometry options will be presented to the user accordingly.  Of the conditions automatically discovered by EFR, only one may be selected to control the design.  The user should select whichever conditions is deemed to be the most appropriate limitation for a safe design calculation.

 

 

 

 

 

In addition to the auto-detected geometry options, the user also has the option to specify an arbitrary custom T-Beam effective width geometry using the table row marked "Override".  Override geometry is set by manually editing the "Side 1" and "Side 2" cells to the desired effective widths.  The "Total" cell value will update automatically as each side is modified:

 

 

 

Note that if the total effective width cell value is zero, then clicking the "Select" button on the "Override" table row will NOT cause the calculation to launch.  This button will not respond until one or both side width override values are set to non-zero amounts:

 

 

 

 

When a concrete beam calculation loads in the ENERCALC interface, the user will not find options to toggle the beam section type (unlike conventional non-Revit-linked calculations).  If a concrete beam is sent to ENERCALC as a T Beam, then the calculation will load with only this option displayed:

 

 

 

 

Users will also note that the "Top Flange Width" and "Top Flange Thick" input values that define T-Beam geometry are NOT available for modification in the ENERCALC interface.  These values are driven exclusively by the physical geometry of the Revit model, or by user overrides applied during calculation launch:

 

 

 

The value displayed for "Total Height" of the beam uses the same behavior described in Rectangular Beam Sections - Joined.  The total height assigned to the T-Beam will represent the combined effect of 1.) slab thickness, 2.) beam depth, and 3.) slab and beam relative locations (i.e., vertical offsets).  Similarly, when the calculation is saved, the Revit model will be updated with a new beam section geometry which creates the proper overall design depth in conjunction with the slab.  As a result, the gross dimensions of the beam element itself may not necessarily match the design depth shown in ENERCALC, but the overall combined depth will match.