Responce Spectrum Analysis and its results
Responce Spectrum Analysis and its results
(OP)
hi,
when we use the Responce Spectrum analysis, because of the mode combination methods (CQC, SRSS) all the results such as forces and moments have the same sign and all are positive. my question is how we can find out which one is positive and which is negative? which one is tension force and which is compression force? . . . There are some procedures that we can use to find out this , but none of them is practical to use in softwares. I need a guide that can be used in structural design softwares such as SAP & ETABS and use analysis results directly to design and Iterate to achieve convergance in final design in shortest possible time.
Thanks alot.
when we use the Responce Spectrum analysis, because of the mode combination methods (CQC, SRSS) all the results such as forces and moments have the same sign and all are positive. my question is how we can find out which one is positive and which is negative? which one is tension force and which is compression force? . . . There are some procedures that we can use to find out this , but none of them is practical to use in softwares. I need a guide that can be used in structural design softwares such as SAP & ETABS and use analysis results directly to design and Iterate to achieve convergance in final design in shortest possible time.
Thanks alot.





RE: Responce Spectrum Analysis and its results
The beauty of the RSA is the simplicity and the high degree of certainity associated with the "maximum" value. The downside is giving up the notion of what a structure's response is every fraction of a second. Which, for the most part, unnecessary. However, to achieve the time-history analysis of a structure you have to use that method of analysis (time history). The problem with the time history is that it is only good for a single location, single event, and is very sensitive to the soil-site investigation and scaling of known accelograms.
Regards,

Qshake
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
RE: Responce Spectrum Analysis and its results
If you desire the response of a structure every second for a forty second or more period then you will have to use the time history analysis. And as I've stated above the input is far more complicated.
Regards,

Qshake
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
RE: Responce Spectrum Analysis and its results
tg