Solutions Discussed: Structural analysis and design of concrete-framed buildings
Products Discussed: RAM Structural System
1) Rotate the view of the model dynamically
When viewing the 3D perspective of model (the default screen in Steel Column and RAM Concrete), it is well known that the view of the structure can be panned by dragging the mouse with the left mouse button. What is lesser known is that holding down the CTRL key while doing this will cause the view to rotate. This is often quicker and easier than rotating through use of the arrow keys.
2) Export a floor you have created in RAM Concept to RAM Structural System
This feature is now available in RAM Concept r3.2. RAM Concept now offers the option to export the floor, including slab, beams, columns, and walls, into RAM Structural System as a new floor layout type. This opens up a whole new flexibility in the concrete building workflow.
3) Reduce your RAM Frame analysis time by creating an eigenvalue load case
The modes of vibration of the structure are computed in RAM Frame in some situations even where no seismic or dynamic load cases are created. An example is the IBC 2006 wind load generation, which uses the fundamental periods of the structure to determine the design loads. By default, RAM Frame uses the total possible number of modes calculated for the structure. For a large building this can mean thousands of modes and an undesirably long analysis time.
The solution to this is simply to create a dynamic load case of the "eigenvalue" type. Then set the number of modes to consider to a more reasonable value. The modal participation report can be used to verify that sufficient mass participation is achieved. For very large structures that utilize semi-rigid diaphragms, the analysis time could very well go from hours down to a few minutes.
4) Model a pile-supported mat foundation using a floor layout
The conventional means of modeling a foundation in RAM Structural System is to lay out a spread footing, continuous footing, pile cap, or mat in Modeler. The spreads, continuous, and pile caps are then designed in RAM Foundation, and the mat can be exported to RAM Concept and the design conducted there. But what if something more elaborate is required?
A pile-supported mat is a good example of a foundation system that can be modeled in RAM using an individual layout type reserved solely for the foundation. The mat itself is modeled via a two-way slab, with an appropriate thickness set. Circular concrete columns are then added at the desired locations beneath the slab to represent the piles. The story height for the foundation level will reflect the depth of the piles. If pile depths vary, another layout type and story can be created with the deeper piles continuing down to the base of this level.
In RAM Frame, the story corresponding to the mat can be assigned as the ground level. Thus no lateral translation occurs at or beneath the mat.
5) Export report data to a spreadsheet
The data in any report in RAM Structural System can be sent to a text file or csv format. To do this simply select "File" as the option before viewing the report (as opposed to the usual "Screen"). From here the text can be opened in a spreadsheet for further post-processing.
6) View stress contours for walls
In RAM Frame, prior to running the analysis, make sure you have selected "Store wall stresses" in the General Criteria dialog. Now run the analysis. Next open RAM Concrete and run the shear wall design. In the View/Update dialog, below the 3D view window, select to view the mesh, and select the type of stress to display. Now select any load combination on the Axial/Flexural tab and the stresses for this load combination will be drawn.
7) Print the ACI axial-flexural interaction data points for a concrete column
One of the additions to RAM Concrete in V14.0 was a report in Concrete Column that lists the P vs. M data for a selected column. So the interaction points that make up the graphic in the View/Update dialog can now be sent to a report for more detailed processing (into a spreadsheet, for instance).
8) Use nodal loads
Nodal loads are a convenient way to account for various types of loads. Remember that in Modeler you need to be in elevation view mode for the nodal load menus to be visible.
9) Create customized reinforcing tables
The *.ren files in the RAM data directory are the reinforcing bar tables RAM Concrete chooses the bars from when designing. The table is selected in RAM Manager. To create your own table simply copy an existing file and edit it as desired. The new table will now be available for selection the next time you choose a bar table.
10) Develop an instinct for expected building proportions
Young engineers today have great opportunities to utilize the industry's latest technology not only for the benefit of their company, but also for their own understanding of buildings. It has never been easier to move through the entire structural design process for a building, including the creation of the building model, analysis for gravity and lateral forces, design of the steel and concrete superstructure, and design of the foundation system. With a platform like RAM Structural System, the impact of various inputs, such as bay dimensions, floor loads, seismic criteria, material properties, and member dimensions, can be assessed relatively quickly due to the integrated nature and reusability of the data within the model. With enough repetitions of this exercise, engineers can get to a point where their preliminary estimates of the building proportions are very close to the final requirements (and few things are more impressive in a young engineer than a good feel for expected member proportions). With today's technology the time it takes to get to this point has been drastically reduced. Stand alone software applications have this ability to "teach" when it comes to individual members or components, but very few platforms can make the same claim for the systematic evaluation of the building.
Thanks for Tip #8 on Nodal Loads. The RAM Frame help file and pdf manual neither would tell how to get to the nodal loads input, just that they were input in Modeler. The manual mentioned that they were input under PropTable, but not that that option only shows up in an elevation view. Thanks for stating that. I was going crazy trying to find how to input them. Now if I could just get RAM Frame to recognize the load I input in Modeler.
Nam, I faced the same problem as you did. I think its a bug in the software. Josh, the moment capacities reported are those of the steel sections and not the composite sections.
Thank you for your tips. ABout the tip #5, co you provide more details about how to export beam design? I tried to export the beam summary into a text file. However, the file only contains the moment capacity (Mn) of non-composite design while my beams were designed as composite members.
Great tips. Thanks Josh:)