Please refer to the Response Spectrum Functions topic for help with the Function Name and Function Damping Ratio edit boxes, Defined Function area, Convert to User Defined button, Function Graph and Plot Options of the form.
The 2004 Eurocode 8 response spectrum function is constructed as described in EN 1998-1-1:2004 Section 3.2.2.5.
Country drop-down list. Choose the country for the function definition.
Direction drop-down list. Choose is the function is horizontal or vertical. When the Horizontal option is selected, the Ground Type and Soil Factor are considered. When the Vertical option is selected, the function considers the Acceleration Ratio, Avg/g.
Ground Acceleration, ag/g edit box. Any positive, nonzero value can be specified for the design ground acceleration.
Spectrum Type drop-down list. Select a spectrum type of 1 or 2.
Ground Type drop-down list. The ground type can be A, B, C, D or E. See EN 1998-1:2004 Section 3.1.2 for site subsoil class definitions. The ground type in combination with the period, T1, are used to look up the spectral design spectrum, Sd(T1), as described in Subsection 3.2.2.5 of the EN 1998-1:2004.
Soil Factor, S drop-down list. Depends on the specified ground type and spectrum type. Taken from Table 3.2 or 3.3 in 1998 Eurocode EN 1998-1-1:2004 Section 3.2.2.5.
Acceleration Ratio, Avg/g edit box. Depends on the specified ground type and spectrum type. Taken from Table 3.2 or 3.3 in 1998 Eurocode EN 1998-1-1:2004 Section 3.2.2.5.
Spectrum Period, Tb display box. Depends on the specified ground type and spectrum type. Taken from Table 3.2 or 3.3 in 1998 Eurocode EN 1998-1-1:2004 Section 3.2.2.5.
Spectrum Period, Tc display box. Depends on the specified ground type and spectrum type. Taken from Table 3.2 or 3.3 in 1998 Eurocode EN 1998-1-1:2004 Section 3.2.2.5.
Spectrum Period, Td display box. Depends on the specified ground type and spectrum type. Taken from Table 3.2 or 3.3 in 1998 Eurocode EN 1998-1-1:2004 Section 3.2.2.5.
Lower Bound Factor, Beta edit box. The lower bound factor for horizontal design spectrum, β, is given in the National annex. The default value of β is 0.2.
Behavior Factor, q edit box. The behavior correction factor must satisfy q ³ 1.5 (the program will accept any nonzero value).
The ordinates of the response spectrum are calculated using Eqns. 3.13 through 3.16 in EN 1998-1-1:2004 Section 3.2.2.5. The values of Tb, Tc, Td, and S are taken from Table 3.2 or 3.3 in 1998 Eurocode EN 1998-1-1:2004 Section 3.2.2.5. Note that the value of these items depends on the specified ground type and spectrum type.
Access the EuroCode8 - 2004 Function Definition form as follows:
Click the Define menu > Functions > Response Spectrum command to display the Define Response Spectrum Functions form. Then do one of the following:
Select EUROCODE8-2004 from the Choose Function Type to Add drop-down list; click the Add New Function button.
Highlight an existing EUROCODE8-2004 function definition in the Response Spectra display area and click the Modify/Show Spectrum button.