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Re: Response Spectrum Analysis
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- Subject: Re: Response Spectrum Analysis
- From: "Jason Emoto" <jasone(--nospam--at)kpff.com>
- Date: Fri, 4 Feb 2000 10:12:40 -0800
The equations for spectral accelerations for the '97 UBC design response spectra (Figure 16-3) are as follows: IF T<To SA = Ca+1.5*Ca/To*T*g IF To<T<Ts SA = 2.5*Ca*g IF T>Ts SA = Cv/T*g Plugging your values into these equations yields: T(s) SA(g) 0.000 0.360 0.120 0.900 0.600 0.900 1.600 0.875 2.600 0.850 3.600 0.825 4.600 0.800 5.600 0.775 6.600 0.750 7.600 0.725 8.600 0.700 9.600 0.675 The number of period time steps you use will affect the accuracy of your analysis. Because these numbers are fairly easy to generate using a spreadsheet and computing time is pretty fast these days, I would recommend using a fairly small time step after Ts. Jason Emoto ----- Original Message ----- From: "Gobo, Gina" <ggobo(--nospam--at)DLRGROUP.com> To: "'seaint'" <seaint(--nospam--at)seaint.org> Sent: Friday, February 04, 2000 9:47 AM Subject: Response Spectrum Analysis I am doing a response spectrum analysis of a steel covered playground. I am using an older version of SAP2000 that has the 94 UBC response spectrum functions for soil types S1, S2, S3. I would like to manually input a response spectrum from the 97UBC. I understand that when T = 0, Ca = 1.00 and from To through Ts Ca = 2.5. What I am not clear about are the points in between. I know that when T>Ts, Ca =Cv/T, but I was not sure what increments of T should be used. I just used increments of 1.00. after Ts. I have generated the response spectrum curve from the 97UBC as follows: Cv = 0.54 Ca = 0.36 T Ca 0 1 .12 2.5 .60 2.5 1.6 0.34 2.6 0.21 3.6 0.15 4.6 0.12 5.6 0.10 6.6 0.08 7.6 0.07 8.6 0.06 9.6 0.06 Is this correct? or, should I figure out an equal number of increments from Ts = 1.6 to T = 10? Does someone have an example function that I could look at? What parameters are typically used for the response spectrum analysis using SAP2000? Thanks in advance, Gina T. Gobo, E.I.T. Structural Engineering DLR Group Seattle Ph. 206.461.6000 Fax 206.461.6049 ggobo(--nospam--at)dlrgroup.com
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