I am performing a dynamic analysis (Response Spectrum) for a Structure with 2 basement levels. I have some queries regarding the use of STAAD commands to model the soil - structure interaction.
Results of static and dynamic analysis are combined using LOAD COMB command.
A finite element model of the basement levels was developed with STAAD. The basement walls were modeled as PLATE elements connected to beams and columns.
In order to model the soil as Winkler spring calculated on the basis of the modulus of subgrade reaction of soil, each joint of beam and column members have to be attached to a soil spring calculated on the basis of the influence area of that joint. Similarly, each joint of the plate elements have to be attached also to a soil spring representing the influence area of that plate element............. How to do this?
I was looking the example problem No. 27, an example to illustrate the usage of commands necessary to apply the compression only attribute to spring supports for a slab on grade, where the command used to instruct STAAD to generate support springs which are effective in the global Y direction was the STAAD facility for automatic generation of spring supports to model footings and foundation mats ..... But for the basement levels I don't think this is OK....?
All the appropriate loads including hydrostatic pressure on the basement walls were input in STAAD.
I was thinking to use the Spring Tension/Compression Specification, but based on the Technical Reference Manual, Section 5.27.5,........
"The SPRING TENSION command should not be used if the following load cases are present : Response Spectrum load case, Time History Load case, Moving Load case. If used, the SPRING TENSION /COMPRESSION will be ignored in all load cases."
"Do not use Load Combination to combine these cases. Tension/Compression cases are non-linear and should not be linearly combined as in Load Combination. Use a primary load case with the Repeat Load command."
What can I do.......?
Any help you can give me to model the soil-structure interaction would be appreciated.
Best Regards,
VETP
Dear Mr. Chris,
Thank you very much by your time and by your valuable opinion about this matter. Very usefull to improve my knowledge and to learn more about the capabilities of the STAAD to perform this type of analysis.