Learn & Support

The analysis of the seismicity according to Eurocode EN 1998-1

Forum » General » General Discussion
Pages: 1
The analysis of the seismicity according to Eurocode EN 1998-1, (dynamic load case type 44)
Good evening! Help me to understand, please. I want to analyze seismicity in accordance to Eurocode and I have a few questions for which there are no explanatory answers:
  1. It is necessary to set independently a few parameters. It is all clear with behavior factor and soils. The last factor probably is betta, that is equal to 0.2 (correct me if I wrong). What is "correction factor for earthquake loads"? Is it building importance factor gamma 1? If no, how to take into account the importance factor of the building? Finally, main question for parameters: what is regional factor? Eurocode does not have it. How to set it and what it considers?
  2. It is possible to choose only type1 or type2 from spectrum; however, there are other for spectrum coefficients for other countries. Is it somehow possible to set coefficients Tb, Tc, Td and S independently for the spectrum?
  3. It is possible to choose earthquake (5) or special during setting the DCF table. There are only and as normative documents. How it affects the analysis and does it matter?
  4. Is it necessary to set coefficient 0.9 or 1 at transformation of static loads into masses?
I really hope that you will help me to understand, because unlike other modules, there isnt written which coefficient from which table was taken in Eurocode.
Thank you in advance for your help
Dear Anma!
1.      Correction factor allows applying of certain coefficient multiplied by seismic forces in non-standard situations such as non-standard acceleration etc. As a rule, it is equal to 1. It does not apply directly to the rules. Regional factor k refers to the calculation of the spectrum of acceleration in a particular region, also to the lower limit of the graph. You can set it equal to 1.
2.      Parameters Tb, Tc, Td belong to Eurocode. If it is necessary to perform analysis for non-standard spectrum Sd(T), then it is recommended to use response spectrum analysis method (dynamics module 41). There you can specify any custom graph of acceleration (speed, movement) fr om the angular frequency omega.
3.      The calculation of the DCF is performed according to the set of coefficients combinations. Therefore, in principle it does not matter which rules are used for obtaining combinations of forces. However, for reinforcement it is essential. Therefore, it is better to calculate combinations for the DCL, where Eurocode is applied.
4.      In accordance to the transition of static load cases in the mass weights depends on the type of loading: Dead (D), Live (L), Short-term (Sh). Therefore, the mass weight for seismicity analysis is recommended to calculate according to the formula Weight=0.9*D+0.8*l+0.5*Sh.
5.      By the way, these types of load cases in the DCF should be applied with the same coefficients.
According to Eurocode the similar formula is different:
Weight = G+ 0.5*Q1 + 0.35*Q wh ere Q1 is Leading variable load; In - Other Variable loads.
Sincerely, E. Streletskii.
Thank you very much for your reply.
  1. Do I understand correctly that in the module 41 I set the spectrum by myself? (which previously had been calculated by Eurocode and set Tb, Tc, Td, S from the national application). Please see the example of the spectrum. Should it be set in such a way in the module? The first column is the angular frequency (rad/sec) - calculated from the time period taken at intervals of 0.05 seconds (in general from 0 to 4, s) (may be I have to be more often?).
  2. In the second column the rspectrum, which has already taken into account the gravitational acceleration g, then as I understood, I put the coefficient equal to 1, instead of 9.81?
  3. Also, please explain me which value do I need to choose: acceleration, velocity or displacement? How it affects the calculation?
Thanks again for your reply.
Pages: 1
Users browsing this topic