In STAAD Foundation Advanced, I have a machine foundation that will end up having 10 different reciprocating machines on a large 50'x75'x11' foundation with high dynamic loads and frequency. Is there any way to model multiple machines that may be reciprocating without being in sync with one another in the Vibrating Machine Module?
No as of now, there is no way to that in STAAD Foundation Advanced. You would need to use STAAD.Pro for this. Model the mat using a mesh of plates and apply these dynamic loads at appropriate locations as time history loading ( harmonic function).
Are there any good tutorials for how to do a mat for a machine foundation in STAAD.Pro. I have found other models that have done something similar but I think I am running into an issue with meshing such a large mass that so many nodes are created and the program seems to just crash or run so slowly that after the plates are assigned that much else can be done.
The key is to use a mesh size that is not too fine as that may lead to creation of too many plate elements and you may not actually need that many. I would say try to limit the number of plates to under 10,000.
Although there is no tutorial specific to modeling a mat for machine foundation but you may take a look at the following Learn Server video which talks about the various meshing options that you will need to generate the mat.
https://learn.bentley.com/app/VideoPlayer/LinkToIndividualCourse?LearningPathID=111693&CourseId=125072&MediaID=5016458
In addition, the following page has a document on analyzing mat foundation in STAAD.Pro that you may download and check out ( ensure that you are logged in )
https://communities.bentley.com/products/ram-staad/m/structural_analysis_and_design_gallery/253408?CommentId=2559d31e-316f-4401-92d7-e9cb19603ba4
I believe that I may have the model properly working but still have a few questions. I will attach the model in case that will be helpful for seeing if the mat is behaving properly.
The mat is modeled as a 1'-0" x 1'-0" mesh of plates with each plate being 11'-0" thick. A spring support is applied at the bottom of the mat with the lower of the soil stiffness (vert vs horz) supplied by the geotech applied in all directions. I went though design example 22 as best as I could to set up the analysis. The loading is broken into static and dynamic over a certain area.
Criteria of the mat are as follows.
Max 10 Total Units Running Independently at Once
Unit Size = 17'-0" x 4'-0"
Max Accel - 0.1 G
Max Velocity - 0.5 in/s
Max Displace - 0.005 in
Max Operating Frequency - 40 Hz
Vert Static - 18 kips = 0.265 KSF
Vert Dynamic - 60 kips = 0.882 KSF
Horz Dynamic - 35 kips = .515 KSF & 22 kips = 0.324 KSF
My questions are as follows.
1. I want the vertical loads on one half to going up will the other loads are going down. Is this done by using a sin function on the one side and cosine on the other, as done in the model?
2. For dynamic loads, I have the amplitude in the time history functions applied at the made KSF for each vertical and horizontal load. Do these loads also need to be applied as uniform loads on the plates and then also as time history loads? Should the static load be applied on the plates and then the dynamic loads applied with the time history? I guess I am unsure which loading to apply in which state from the example.
3. When applying the damping properties in the time-history function, is the damping to be the damping of the soil, or the internal damping of the concrete?
4. I've figured out how to get the maximum displacements of the foundation, is there a way to get maximum velocities of the foundation?
1121.Slab.STD