The RAM Steel Column Module is the module where gravity columns and gravity base plates are optimized. Unsized lateral columns are also assigned a preliminary size. All columns in this module are assumed to be simply supported and they are designed for Dead and Live Load applied on one-way decks only. Base plates are optimized for Dead and Live Load only although the columns will be designed for moments induced by the eccentricity of the supported beam connections. This section can only be completed if you have installed the RAM Steel program and have a license available. To invoke the Steel Column module from RAM Manager:
The graphical area will then show a 3D view of the building with the steel columns show in design colors and the other members in grey. You might think of them as status colors. The various colors and the meanings are listed below. (Note that you should only see yellow steel columns upon entering the steel column program with the tutorial model).
The graphics will change to the pen colors used in the Modeler.
A third color option called Interaction Colors is available after the columns have been designed.
Besides altering colors, you may also want to change the information or members displayed in the graphics window. To alter the text or members that are shown:
This dialog box is organized by the various types of members. Each can be labeled with a variety of labels or turned off completely.
Sometimes it's easier to work in Plan or Elevation mode than in 3D. If that's the case you can select View - Elevation or View - Plan. An additional option in the Steel Column module is to View - Column Plan. This takes you to a compressed aerial view where you can see the entire 3D structure from above with no perspective.
As with the Beam design module, a light in the lower right corner indicates the current status of the file. When the designs are all current the light will be green.
The RAM Steel Column module automatically detects the brace points for columns based on the framing. When a beam or joist frames into a column it braces the column in that axis. In the case of skewed framing, there is a maximum angle for which this is true.
Notice that the deck can also be sufficient to brace interior columns when there are no beams framing into it. In some cases you may wish to alter the program determined brace points. To do so now:
As soon as the command is started, the graphic will indicate the current brace locations using green triangles in the plan of the bracing.
Column splices are also preset when entering the Steel Column Module. When we defined the story data in the modeler, this also established the splice levels. When the story data was specified to have a splice at the 4th floor (story #3), that tells the program to change size for the columns above this level. The columns between 4th and 5th floors won't change size. There are exceptions to this rule, places where the program will splice the column at non-splice levels. These automatic or temporary splice location result whenever the column changes material, shape or orientation between levels. Lateral columns can also have splice at non-splice levels since the column sizes are specified level-by-level.
The splices are indicated as red squares at the levels where the splice occurs. In practice, the splice will be a few feet above the floor but for the purpose of design, the column size changes just above the level.
Columns and Base Plates may be designed per requirements of five different codes including Allowable Stress Design (ASD), Load and Resistance Factor Design (LRFD), Canadian (CAN/CSA - S16.1 - 94), British (BS5950:1990 or 2000) and Eurocode. For more information about design codes see the Design Codes Section in the RAM Steel Column documentation. To set the design codes:
The Gravity Column program uses trial groups to optimize column sizes. In the Modeler, columns are assigned shape (I, HSS, Pipe), material strength and orientation. The design of the columns is performed by selecting the lightest adequate column size from a maximum of three column groups.
Column groups are identified by the section depth in the designation (e.g. W12, UC254, etc.). The program will select the lightest column from the available column groups which are defined in the Column Design Table.
If any changes are made to the trial groups, you will receive a message asking if you want to assign new trial groups to existing column lines.
NOTE: This criteria applies to the whole model globally. When one column line needs to be designed using a different sizes, they may be assigned to that column line by selecting the Assign - Trial Groups command.
The columns are now ready to be designed. The Process - Design All menu item may be selected to perform the design of all columns or the View/Update menu item may be selected to look at one particular column line.
Once complete, the view will automatically shift to showing the interaction colors. A dialog box labeled Color Scale opens.
NOTE: This box may be moved if it is in the way of a menu item or icon you wish to use.
Notice that all of the columns are checked, even the lateral columns. It is important to note that the design of the lateral columns is not complete. So far, the columns have been checked for gravity loads only (and those loads are based on simple, tributary areas). The effect of moment connections, braces, and lateral loads is only examined in RAM Frame.
When a column spans multiple levels, each segment of the column will be checked independently, but each will use the overall, multi-story unbraced length in the design. To review the results for a particular member:
The interactive View/Update dialog box that opens has many important functions. In the upper left corner is the final design, the sizes selected by the program for each level. If there are more than 8 stories, the slider on the right side will allow you to scroll down. Information about the splicing, bracing and yield stress of the columns as well as the current interaction ratio also appear in the upper left area.
If a sloping column is selected you will notice a series of colors indicating dependencies of that column. For more information on column dependencies see the steel column manual by clicking Help-Manual.
In the upper right area are the results for the three trial groups (assuming three were used). The program will select the lightest working design from the three trial groups. In this case, there were no HSS6x6 columns sufficient to support the loads with no intermediate bracing so the Trial Group 1 indicates "None Worked". Either HSS10x10 or HSS 12x12 will work, but the 10x10 sections are lighter, so they were selected by default.
When the View/Update dialog opens for a particular column line, the top column of the column line will be highlighted in white between splices. In this case, that is the 3rd level only.
NOTE: At this time, nothing in the grid has changed. The original optimized size and interaction value are still listed under the Final Design.
Now we will investigate the design of another column line.
NOTE: If a View/Update is done on a column line containing floors with unspliced levels, highlighting one of the floors (4th for example) causes the program to highlight the continuous levels together.
The result of the controlling column segment (in this case the 4th floor controls) will be indicated on the Story - Analyze tab.
Do NOT click the Select button to choose this new size as part of the final design.
To review the results for the selected column:
The design report starts with the top level. Click page down to proceed to the other levels. Notice that the columns are being designed for axial loads and moments using the full unbraced length. The moments are a result of the eccentricity of the beam connections. The column eccentricity may be set in the Modeler using Layout - Columns - Assign Eccentricity. The program considers all possible patterns of live load when evaluating the column design and the governing combination of patterns used at the top and bottom of the column determines the design data that is reported here. To turn off the skip loading altogether, go to Criteria - Design Defaults. Refer to the technical notes in the RAM Steel Column documentation for an explanation of the design methods and results.
In the graphics mode, the column now appears with the modified interaction colors. Feel free to View/Update other columns in the model.
The Story - Optimize and Column Line tabs provide other options for investigation. Using the Story - Optimize tab for example, you can see what size "HSS" section would work for the column at B-1 even though it was initially modeled as an I section.
If you have one column saved with the sizes you want to keep, that column line design can be easily copied to other column lines.
At this point, the program is going to make the column at R-4 just like the column at R-2. This saves you the step of performing a View/Update on all columns with identical designs.
NOTE: If the new design is insufficient for the column at R-4, then a warning message will pop up asking if you want to cancel the operation.
At certain stages of the project you might want to freeze the column designs without making any changes to the program selected sizes.
The Target cursor will appear and any column line you select will be frozen. The sizes will not be re-optimized by the program unless cleared first. Using the [Update Database] button in the View/Update dialog box is the same as freezing a column line.
User assigned or frozen column sizes may be cleared by using one of the Process - Clear Design commands from the menu.
NOTE: Process - Clear Design - All will only clear sizes from the gravity columns. If you want to clear the sizes of lateral columns, you must use the Process - Clear Design - Column Line command.
Several reports are available from the Reports Menu including all Summary Reports for column, column loads and base plate design.
Because the program alternates Live Loads on columns to obtain the controlling combination of unbalanced moment and axial loads, the Column Summary report should not be used to obtain maximum loads at column bases. The total loads are reported in the Loads Report or Loads Summary report. A steel takeoff of all gravity columns is also available from the Reports menu:
NOTE: You can save your model at any time form any module, but you are not required to save before exiting. If you close the Manager completely or change to another model, then the program will prompt you to save any recent changes.