STATIC SEISMIC ANALYSIS

Equivalent static seismic load generation as per EC8 is currently not available in STAAD.Pro. One can do a response spectrum load generation as per the EC8, in case that helps.

Hi Sye

Can you please let me know where I can find a step by step example for EC8, I could find this one below but no step by step

You can refer to that attached example-

Eurocode8_RC designer.std

How the ZPA acceleration value is set on frequency units, 33 HZ. The acceleration should be on unitary values of g. What value of g correspond to 33Hz

Please refer to the attached section of Technical Reference manual. The parameter value used in ZPA corresponds to Hz.

PDF

Just want to add that ZPA value is used for missing mass correction only.

"Zero Period Acceleration" refers to spectral acceleration for a (near) zero period structure or an extremely rigid SDOF structure under an earthquake excitation. So, the units of ZPA is indeed the units of acceleration and the value would be equal to the ground acceleration.

If you look into the Technical Reference Manual, you will see that you would need to enter a value f6 (please refer to Technical Reference Section that DSANJU has produced in his response). You would need to enter that value along with "MIS" parameter. "MIS" represents the command to the program to calculate the missing mass from the difference of total mass and the cimulative mass that has been considered in the number of modes considered. f6 is nothing but the spectral acceleration related to the rigid SDOFs. So, the units are in the units of acceleration.

However, if you choose to specify the boundary frequency beyond which the structure can be considered to be rigid in stiffness - then the ZPA can be read off from the spectral data specification against the value of frequency (reciprocal of the boundary time period). In the Technical reference, the ZPA f7, expects f7 in frequency against which the ZPA would be read off from the spectral data specification.

33 Hz is generally considered as the boundary frequency from which the  modes can be considered as rigid under earthquake excitation.

I hope this explains.

"Zero Period Acceleration" refers to spectral acceleration for a (near) zero period structure or an extremely rigid SDOF structure under an earthquake excitation. So, the units of ZPA is indeed the units of acceleration and the value would be equal to the ground acceleration.

If you look into the Technical Reference Manual, you will see that you would need to enter a value f6 (please refer to Technical Reference Section that DSANJU has produced in his response). You would need to enter that value along with "MIS" parameter. "MIS" represents the command to the program to calculate the missing mass from the difference of total mass and the cimulative mass that has been considered in the number of modes considered. f6 is nothing but the spectral acceleration related to the rigid SDOFs. So, the units are in the units of acceleration.

However, if you choose to specify the boundary frequency beyond which the structure can be considered to be rigid in stiffness - then the ZPA can be read off from the spectral data specification against the value of frequency (reciprocal of the boundary time period). In the Technical reference, the ZPA f7, expects f7 in frequency against which the ZPA would be read off from the spectral data specification.

33 Hz is generally considered as the boundary frequency from which the  modes can be considered as rigid under earthquake excitation.

I hope this explains.