General
...
| Info |
|---|
This page is devoted to frequently asked questions (FAQ) related to Modeling techniques. |
On this page:
| Table of Contents |
|---|
How is flange local buckling
...
checked?
Extended Question: Is it possible to check for flange local buckling in SAP2000? I am trying to apply load to a column but the model always assumes the load transfers to through the center mass, so how can I make sure that the load is applied to the flange of the W shape column only?
Answer: You would need to create local model to evaluate the local flange buckling. This could be done by modeling the column flanges and webs using shell elements and by evaluating only a local portion of the model in the vicinity of the point of interest. The loads and boundary conditions would need to be applied in such a way that the interaction with the rest of the model is correctly accounted for.
How can I model a deep beam?
Since SAP2000 frame element formulation includes both bending and shear deformations, frame elements can be used to model deep beams. This may be reasonable approach to evaluate global response, but localized response may need to be determined by a more refined model. For example, the beam could be modeled by shell or solid elements. Depending on the beam material, it may be also worthwhile to use more specialized methods, such as the strut and tie method for the analysis and design of reinforced concrete deep beams.
How can I model as simple beam model that is subjected to cyclic loading?
You can evaluate this behavior by performing time history analysis or staged construction analysis.
The time history analysis will solve the problem including the dynamic effects. You may apply the loads slowly (quasi-statically) to disregard the dynamic effects. The speed of load application to disregard these dynamic effects would be structure dependent and would be influenced by factors such as the natural frequencies of the structure. You may determine this yourself by trying different speeds of load application and checking the sensitivity of the response.
If you do not want to use time history analysis, you could also use staged construction analysis. You would need to add the entire structure in the first stage and then define separate stages for each load application increment.
How does SAP2000 consider the safety factor for the analysis and design?
Depending on the design methodology, the safety factors can be considered either by increasing the applied loads or by decreasing the resistance of the structural members. This can be done by means such as I am interested in loading the flange of a W-section column, but the load seems to transfer through the center of mass. How is flange local buckling modeled and analyzed?
Answer: Flange local buckling may be evaluated by creating a local model where shell objects simulate the column web and flanges. Loads and boundary conditions should be applied in a manner which correctly accounts for interaction with the global model.
Additional information is available in the warping article.
How is a deep beam modeled?
Answer: Frame objects may be used to model deep beams since frame formulation includes both bending and shear deformation. While this should be sufficient for global response, a more refined local model may be necessary for localized response. Shell and solid objects may be useful for creating a local model, and such specialized methods as strut-and-tie modeling may be worthwhile if analysis and design involves reinforced-concrete materials.
How is a simple beam model subjected to cyclic loading?
Answer: Cyclic loading may be evaluated through either of the following methods:
- Time-history analysis, where the dynamic effects of load application are taken into account. Dynamic effects are dependent upon the rate of load application, along with properties inherent to the structure itself, such as natural frequencies. Load may be applied slowly, in a quasi-static manner, such that dynamic effects are negligible, or at the rate desired. To gauge the sensitivity of response, various rates may be applied and compared.
- Staged-construction analysis, where the entire structure is added in the first stage, then separate stages are defined for each increment of load application.
How is safety factor considered during analysis and design?
Answer: Depending on design methodology, safety factors may be considered by applying a factor which either reduces the resistance of structural members (ASD), or increases the magnitude of loading (LRFD). This may be accomplished through a number of means, including factored load combinations, allowable stresses, resistance factors, etc. SAP2000 allows the user to set up The modeling procedure appropriate for any given project depends on the building code being followed. CSI Software then enables factored load combinations and perform design procedures to be based on allowable stresses or ultimate resistance, but the way to set up the model would really depend on the design code that you are using.
Is there a command to copy objects along with their assignments?
Answer: The replication feature replicates objects along with their assignments, including loads, restraints, constraints, etc. Replication, however, is not applicable to group assignments, as is described in the Replication of group assignments article.
Cut, copy, and paste commands only transfer the geometry and connectivity of selected objects, and not their assignments. To copy assignments with the objects modeled, select Assign > Copy Assigns and Assign > Paste Assigns.