Response Spectrum ASCE 7-05 Function Definition

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/Display Graph of the form.

Provide input parameters for the following areas on this form:

• Ss and S1 from USGS  - Choose to obtain these values from the United States Geological Survey

• •  User Specified - When this option is selected, specify values for the following:

  •  0.2 Sec Spectral Accel, Ss - The 5% damped design spectral response acceleration at short periods as specified in ASCE 7-05 11.4.1.

  •  1 Sec Spectral Accel, S1 - The 5% damped design spectral response acceleration at a one second period as specified in ASCE 7-05 11.4.1.

  • by Lat/Long (latitude/longitude) - When this option is selected, specify a Site Latitude (degrees) and a Site Longitude (degrees)  to identify the site location, and the program will retrieve the appropriate values for Ss and S1. If needed, click the   button to display the Latitude/Longitude Limits and Discretization - For Information Only form. Use that form to help identify the latitude and longitude for the site location.

  •  by Zip Code - When this option is selected, specify a Site Zip Code (5 Digits) that in turn will identify the latitude and longitude for the site location, and the program will retrieve the appropriate values for Ss and S1.  If needed, click the   button to display the Zip Code Data form. Use that form to select a zip code that will help identify the latitude and longitude for the site location.

• Long-Period Transition Period -  as specified in ASCE 7-05 11.4.5

• Site Class - Site Coefficient, Fa and Site Coefficient, Fv, depend on the Site Class selected. Site class A to F as specified in ASCE 7-05 11.4.2. For all options other than Site Class = F, the values are defaults that cannot be edited. When the Site Class = F, the values can be input by the user.

• Calculated Values for Response Spectrum Curve - These values update automatically as changes are made to the other options on the form. They cannot be adjusted directly.

The ASCE7-05 response spectrum function is based on the procedure described in ASCE 7-05 11.4.

Access the Response Spectrum ASCE 7-05 Function Definition  form as follows:

1. Click the Define menu > Functions > Response Spectrum command to access the Define Response Spectrum Functions form. Then do one of the following:

   • Select ASCE7-05  from the Choose Function Type to Add drop-down list; click the Add New Function button.

   • Highlight an existing ASCE7-05  function definition in the Response Spectra display area and click the Modify/Show Spectrum button.