Hello Everyone,

Can anyone let me know that how should we can put "Spectrum Data Point" manually. I have the inputs from clients "Time periods vs gravity acceleration".

As per CAESAR guide lines, when I entered in "Dynamic Analysis>Tools> Spectrum Data Point" then one window is open to select the spectrum name. But it is blank and I am unable to do further process. Is that I am missing something ? Please guide me.

Thanks
Dhiraj

First you need to generate a spectrum in Dynamic Analysis>Tools>DLF Spectrum Generator and save it. Then you will have this spectrum available in the Spectrum Data Point.
Give a try.

Review the example job "NUREG9", in the /Examples folder.

Thankyou Dan and Richard for reply.

I have gone through the example file "NUREG9". But I have few concern on input parameter:

1. In static model, there is no temperature input. Is there any specific reason for that ?

2. In static model, supports are provided with stiffness values. Are we getting this values from Dynamic analysis ?

3 In Dynamic Input, 4 Support group spectrum are defined. Where we can define that which support are in which group.

4. In Spectrum Load Case Factor factor is 386.4. From where we get this input value.

5. In Lumped masses Mass is defined as 585.948.rom where we get this input value.

6. In control parameter, frequency cutoff value is zero & there is no load case is selected. Are we not going to check any natural frequency for the system.

Thankyou in advance.

Thanks
Dhiraj

1) The NUREG jobs are dynamic benchmarks only - there is no static analysis for these jobs.

2) The support stiffnesses are provided in the NUREG bulletins.

3) Think about piping supported on the ground, then the 1st level of a rack, and also the 2nd level of a rack. The seismic activity excites the supports on the ground. Some of these supports will be pipe supports, others will be the rack supports. As the rack is excited, the supports on the 1st and 2nd level will also be excited, but differently from the ground and from each other. In this example, there would be three support groups. Note though, these other spectra were also provided in the NUREG bulletin - usually you would obtain this information from your Structural group. Alternatively you can model the rack and let CAESAR II do all the work.

4) This is the acceleration of gravity in "in/sec2".

5) This is also an input defined in the NUREG bulletin.

6) The frequency extraction stops at either: the cut-off value you specify, or the number of frequencies you specify. Typically you would use a cut-off value since you don't know how many frequencies exist below any certain value. In this benchmark example, the NUREG bulletin specified the number of frequencies to extract.

You don't need a referenced static load case unless the job is non-linear (has non-linear supports like +Ys, gaps, or friction).

A response spectrum analysis always begins with the natural frequency extraction.

Thankyou Richard for your reply.

Regarding the Lumped mass, I have keep it blank as this is an additional mass which I understand from your reply.

In My Dynamic Output > General Result > Active BCs,
Stiffness is showing zero for all the restraint which having the gap (more than zero) & Loads are showing zero for those restraint. What does it means ? & How I can get the loads for those restraint from dynamic output.

Also can we get the response spectrum for our system in graphical mode ?

Thanks
Dhiraj

Regarding the "lumped mass" input:" In most cases you should model the weight of the system properly - therefore you won't need to specify lumped masses. This is more of an academic input value.

Active BCs: Spectrum dynamics are linear in nature, because of the natural frequency extraction - even if the model includes non-linear restraints. In CAESAR II, we use the referenced static load case to set the non-linear boundary conditions - based on the output of that specific (static) load case. If in that (static) load case, the gaps don't close, those restraints are removed completely from the dynamic model. If the gap does close, the gap is removed from the restraint. Similarly, if you have a +Y in the model, and it lifts off in the referenced static load case, then that restraint is removed completely. If the +Y doesn't lift off in the referenced static load case, it is changed to a full Y support in the dynamic model.