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[GEN/Load]When some criteria do not have a 'Response Correction Factor' or 'Importance Factor' input

Question

When analysing the response spectrum, some of the Design Response Spectrum regulations do not have a response correction factor input field. How do I account for the response correction factor in these cases?

 

 

Answer

GENerates a design response spectrum that includes a response modification factor for some regulations as a convenience, but for most regulations, the elastic spectrum is the default. The elastic spectrum is a pure response spectrum with no response modification factor.

The elastic spectrum is the pure response spectrum without any 'Response modification factor'.
In this case, there are two ways to include the Response modification factor

1. Using Scale Factor in the Response Spectrum Function

2. Using Scale Factor in the Response Spectrum Load Cases

If your response modification factor is 4, you would enter 0.25, which is a quarter, for Scale Factor.

-Elastic spectrum without response modification factor : IBC2000(ASCE7-98), UBC(1997), UBC88-94, NBC(1995), Eurocode-8(2004) Horizontal Elastic Spectrum, Eurocode-8(2004) Vertical Elastic Spectrum, Eurocode-8 (1996) Elastic

- Design spectrum with response modification factor : KBC(2008), KBC(2005), Korea(Arch.2000), Korea(Arch.1992), Korea(Bridge), Eurocode-8(2004) Horizontal Design Spectrum, Eurocode-8(2004) Vertical Design Spectrum, Eurocode-8(1996) Design, China(GB50011-2001), China Shanghai(DGJ08-9-2003), China(JTJ004-89), China(GBJ11-87), Japan(Arch.2000), IS1893(2002), Taiwan(2006), Taiwan(1999) Horizontal, Taiwan(1999) Vertical, TaiwanBrg(89) Horizontal, TaiwanBrg(89) Vertical

 

Question

When applying the response spectrum analysis of the UBC or IBC2000 Code, the response correction factor and significance factor fields are not present, what should I do?

 

Answer

The response modification factor can be reflected in the Scale/Scale Factor.

If the response modification factor is 4, you can simply input a Scale Factor of 0.25.
(Response Spectrum Load Case>SpectrumLoad Case>Scale Factor) Alternatively, in the response spectrum load condition, you can enter a
Scale Factor as 0.25.

The reason there isn't a separate input for this is because the response spectrum is primarily based on elastic response spectra.

Response modification factors and importance factors are related to design response spectra but not to elastic response spectra.

For this reason, when explicitly specified in the code as elastic response spectra, GEN defaults to generating elastic response spectra. Some codes define elastic and design response spectra differently, so both options are provided to accommodate these variations.

In the initial versions of GEN, some codes were addressed by including response modification factors and importance factors in the design response spectra. However, to maintain consistency across various national standards, the approach shifted to generating pure elastic response spectra. In the case of domestic standards in Korea, which have long used design response spectra, the option to continue using response modification factors and importance factors to generate design response spectra has been retained.

 

 

 

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