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ASCE 7-16 Seismic Load Calculations

Using the SkyCiv Load Generator – ASCE 7-16 Seismic Load Calculations for Buildings

SkyCiv introduces the seismic load calculation for buildings using ASCE 7-16 Equivalent Lateral Force procedure. In addition to the parameters for wind and snow loads, the seismic load calculation uses seismic parameters obtained from U.S. Geological Survey (USGS) Web Services. Users will get the following data that can be modified to get the most appropriate seismic load for the structure:

  • Long-period transition period \( {T}_{L} \)
  • Design spectral response acceleration parameter at short period, \( {S}_{DS} \)
  • Design spectral response acceleration parameter at 1s period, \( {S}_{D1} \)
  • Mapped maximum considered earthquake spectral response acceleration parameter, \( {S}_{1} \)

Free users will be able to get these data but will only be able to calculate the seismic loads for a maximum of 3 solves per day. With a Professional Account or by purchasing the standalone Load Generator module, you can use all the features of this calculation as long as you want. You can purchase the standalone module thru this link.

Site Data

Together with the wind speed and ground snow load data, users can get the seismic parameters for the location obtained from USGS Web Services by defining the “Site Class” first and then the location:

ASCE 7-16 Site Site class parameter

Figure 1. ASCE 7-16 additional parameter (site class) for obtaining site seismic parameters.

USGS Seismic Parameters

Figure 2. Site seismic parameters from USGS Web Services.

Users can modify the parameters obtained from USGS Web Services to obtain the most appropriate seismic load for the structure.

Structure Data

To calculate the seismic load for the structure, the structure data should be filled. Moreover, the required site seismic parameters in Site Tab should have values defined. These are: \( {T}_{L} \), \( {S}_{DS} \), \( {S}_{D1} \), and \( {S}_{1} \). By meeting these conditions, you can check the “Calculate Seismic Load” checkbox.

Seismic data  of the structure

Figure 3. Seismic parameters of the structure.

The seismic parameters needed to be defined are the following:

  • Structure system – for determining the values of \({C}_{t} \) and \(x \) which will be used in calculating the approximate fundamental period of the structure \({T}_{a} \)
  • Approximate fundamental period of the structure \({T}_{a} \) – can be user-defined to more appropriate seismic load calculation
  • Response Modification Factor \( R \) – default value is 8.5 and be modified for more appropriate seismic results
  • Redundancy factor, \(  ρ \) – default value is 1.0 and can be modified. Used in diaphragm forces calculation
  • Floor Weights – used for the vertical distribution of base shear and for diaphragm forces. Data per level required are: Level (for designation), Elevation, and Weight

The approximate fundamental period of the structure is automatically calculated as guide for the users when the “Structure system” dropdown is changed. Users are free to edit this value which is affect the corresponding calculated base shear for the structure.

Results

Once all the parameters are defined, clicking the Generate Loads button will give a result as shown below.

Seismic input parameters used in the calculation.

Figure 4. Seismic input parameters used in the calculation.

Calculated seismic forces using the equivalent lateral force procedure.

Figure 5. Calculated seismic forces using the equivalent lateral force procedure.

Detailed Calculation

The detailed seismic load calculations can be accessed only by Professional account users and those who purchased the standalone load generator module. All the parameters and assumptions used in the calculation are displayed on the report to make it transparent to the user. You can download a sample detailed calculation thru this link.

Detailed seismic load calculation generated from SkyCiv Load Generator.

Figure 6. Detailed seismic load calculation generated from SkyCiv Load Generator.

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