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Thanks for your attention!
I have got stuck up generating spectrum in Staad using EC8 2004
Syntax: SPECTRUM CQC EURO 2004 ELASTIC RS1 X 1 Z 0.3 ACC DAMP 0.05 LIN SAVE SOIL TYPE C ALPHA 0.36 Q 2
when i change the Q factor above from 1 to 2 in EC8 2004 definition, i do not see any change in my spectrum values.
Indeed if i use EC8-1994 definition . i could see the change in the spectra values. Im bit worried , i havent done spectrum analysis in staad pro earlier.
Could someone help me on this? I need spectrum for the following conditions. Soil type:C, Q=2; Elastic Type I Spectra, Ground acceleration =0.36g, X=1,Z=0.3
It would be much helpful if someone gives a try and provides me the spectrum(As per EC-8, part -I), Period vs Acceleration values
Many Thanks in anticipation
You have specified the elastic response spectrum. To the best of my knowledge, the behaviour factor Q, does not have an effect on the elastic horizontal/vertical response spectrum. The equations for the spectral values for the elastic spectrum does not contain the term q. The same only has an effect if you use the design response spectrum. Please refer to the clauses 184.108.40.206, 220.127.116.11 and 18.104.22.168 of the EC8:2004 code.
Try using the design response spectrum and let me know if you stil cannot see any change. If not, please upload the STAAD file and i will look into the issue ind details.
Sudip Narayan Choudhury
Thank you very much for your valuable guidance. Its pretty clear now. I have identified where i went wrong. Thanks again.
If i am not bothering you.Just for my satisfaction, could i ask you to review my spectrum definition in staad and drop your comments? It would be of much help. I am attaching staad input file for your perusal. The basic loads are dead load, liveload, and crane loads, along with case A, Case B (seismic loads). In combinations , all the gravity loads + EQ loads .
pls clarify me that i can relay on the results that are generated from the combinations for design of my pile sections.
Many thanks in anticipation.
From the STAAD's point of view, the Eurocode response spectrum specifications appear to be alright to me. Alos, the load combinatins appears to capture all possible situations. However, I think you need to specify the mass definitions only in the first response spectrum load case. I find that you have specified the mass definition twice, once for each response spectrum load case. The mass distribution of a structure is supposed to be constant.