RAM Concrete Beam Tutorial


To design all your concrete beams you need to be in the Concrete Beam Design Mode. To switch to the concrete beam mode:

The mode drop-down on the toolbar will indicate when you are in the Concrete Beam Design Mode. The same toolbar can be used to switch between modes rather than using the menus.
Note; before you can enter the concrete beam design mode, the concrete gravity analysis must be performed. If you have lateral concrete beams you will also want to make sure your model has been analyzed in RAM Frame. If you are unsure of the current status of the model:

To design all your concrete beams you need to be in the Concrete Beam Design Mode. To switch to the concrete beam mode:

The mode drop-down on the toolbar will indicate when you are in the Concrete Beam Design Mode. The same toolbar can be used to switch between modes rather than using the menus.

NOTE: Before you can enter the concrete beam design mode, the concrete gravity analysis must be performed. If you have lateral concrete beams you will also want to make sure your model has been analyzed in RAM Frame. If you are unsure of the current status of the model:

Beam Design Criteria

The program has an extensive set of design defaults to customize the way concrete beams are designed and detailed. First you need to designate the concrete moment frame type:

To set up the beam design defaults which will be used for all beams:

This will result in the program using the code limits for all cover and spacing.

This is the value used by the program to establish the depth of the reinforcing.

At this time, the concrete beam design program does not design beams for additional torsional reinforcing. Nor does it consider the special detailing requirements of deep beams. When a beam exceeds the torsional limit of the concrete or the maximum depth to span ratio a warning will be given. Some users prefer not to get these warnings so that they can concentrate of other types of design issues.

In rare cases, the 3D finite element analysis performed by RAM Frame may actually be more accurate than the floor-by-floor approach used in the Concrete Analysis mode.

Detailing Defaults

To set the defaults for concrete beam bar placement

The Detailing Defaults window will open with separate tabs for Gravity Beams, Gravity Joists and Lateral Beams. Set the various bar lengths and Stirrup start Locations to the values shown in the figure below.

At this point you could also choose to make individual member assignments using the options under the Assign Menu, but for this example we will allow the default settings to apply to all members.

Load Combinations

Before any beams can be designed, you must specify the load combinations to consider. These may be created manually as User Defined Load Combinations or Code Generated Combinations can be utilized. To establish the Combinations for Concrete Design:

The Load Combinations box will be filled with load combinations and each should be checked to Use.

Design All and View/Update

With the design criteria set and the load combinations defined, we are ready to design the concrete beams. At this point, the beams should have changed from a light blue color to yellow, indicating that they are ready to be designed. To design the concrete beams:

The design process requires numerous code checks for all of the Load Combinations and may take some time to run on large concrete models. The status indicator again displays the progress of the design and indicates when the design is complete.

Click [Close] to dismiss this window. The Model graphics will be updated to display in design colors.

Green – Indicates that the beam was designed successfully with no design warnings.

Red – Indicates some aspect of the Concrete Beam design is insufficient or incomplete. Design warnings that elaborate on why a beam design failed can be seen in the View/Update dialog.

Blue – Indicates a successful design is Frozen. (A beam that has failed will always appear red even if it is frozen.) In either case, the way to review the details of the design and make changes if desired is through the View/Update command.

The View/Update dialog box will open as shown below. There are many options available from this dialog. For a complete explanation of the View/Update window see the RAM Concrete manual. For this example, we will touch a couple of the highlights.

The View\Update dialog is broken into 5 separate tabs. The first tab for Longitudinal reinforcement shows by default. The Top Reinforcement is shown by default.

Notice the diagram at the bottom which graphically indicates the reinforcing and plots the demand envelope (yellow diagram) and capacity (blue line) for the length of the member.

To switch the display to show Bottom Reinforcement:

To see the capacity at a particular location:

Changes to the reinforcement can be made in the spreadsheet of reinforcement in the top portion of the dialog.

While reviewing Bottom Reinforcement,

After doing this, the traffic light changes to yellow indicating that the results are no longer current.

The light should still be red in this case indicating that this new layout fails the design checks.

Now we will look at the Transverse Reinforcement.

Notice that the bottom graphic is adjusted to show shear information rather than bending now.

Here the stirrups are grouped into three sections. The first section has #3 stirrups at6” on center and continues for 13’ from the face of the column.

The Concrete Beam Design Report will open. Review the report. For more information on the designs performed in this check refer to the technical portion of the RAM Concrete Manual.

If the new design is acceptable, the color of the member will change to dark blue indicating that the design has been modified. This design will not change again unless it is changed manually, or the design is cleared using the Process – Clear Beam Design command.

There are two significant differences about this beam line. First note that the envelope of the demand moments (the yellow diagram) is thicker than the earlier gravity beam. That’s because this is a lateral member with more load combinations to consider. The second is the traffic light. If the traffic light is red then some aspect of the design has a warning.

To see what that warning is:

This beam happens to have the following warning for each span:

This warning will occur whenever the member Torsion exceeds the minimal capacity of the concrete as specified in the code. It is important to note that the rest of the design is still applicable, despite this warning. To avoid seeing torsion warnings at all:

When you change one of the design criteria you will get a reminder that the designs will have to be rechecked.

Concrete Beam Deflection

Any beams that are still red at this point have some other kind of warning.

Here the table lists the controlling deflection criteria. The first and long spans of the beam line are all within the long term deflection limits set in the deflection criteria.

To see the deflection ratios for all beams at once:

The screen will be updated to display the deflection using a color scale. The graphic can also be set to show Span to deflection ratio, Effective moment of Inertia or Deflection ratio.

Copy Design

Because the design and detailing of concrete beams can be complicated, it is often desired to use an identical bar layout for typical beams. In this example, many of the beams can be detailed the same. To apply identical design of one beam to another:

A target cursor with an arrow will appear with the arrow pointing up indicating that the program is expecting you to select the beam to copy the design from.

The arrow on the cursor will now point down indicating that the program expects you to select the beam to copy that design to.

When a design is copied to a beam, the new design is checked for code compliance. If the design is acceptable, the color of that beam will change to Blue indicating the design is frozen.

If the design is insufficient in the applied beam, then it will be painted red to show that the new design has failed.

The new design can be cleared from the beam by using the Process – Clear Beam Design command as before. The beam will then be colored Yellow to indicate it is no longer frozen and it is ready to be designed. The optimum design will be restored during the next Design-All or View/Update.

Tolerance and the copy command:

While the Tolerance Setting is set to “Perform copy only if beam lines are geometrically identical” copying the design from one beam to another will only occur if the geometry is identical. For example, you could not copy the beam reinforcing from a beam that spans between two columns to one of the infill beams because the support conditions are different. This makes the Single-to-Fence and Single-to-All copy options quite useful because you don’t have to worry about copying rebar that won’t fit in the various beams.

When the Tolerance Setting is set to “Perform copy if clear length of each corresponding spans is with ___%”, a greater number of beams can receive the copied design.

Because we selected to only allow copying between  beams with identical geometry, the only beam that is affected by this copy is the other beam on gridline 1. The rest of the beams maintain their design.

Reports

Many different reports can be generated from the Concrete Beam Module. The printed output is mostly generated using the Reports menu.

To print the load combinations used in concrete design:

To print a summary of the concrete beam designs:

A similar output is available for a single member through the View/Update dialog box by clicking [View Summary]. The complete design results are also available from the report menu.

Take time now to review the various reports available in the Reports menu.