Used to input seismic load data—either directly or by parameters which the program will then use to calculate code-specified seismic loads. The following codes are supported:
- ASCE 7-2005 (US)
- IS-1893 Part 1 (Indian)
| Setting | Description |
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| Direct Seismic Load Input |
Set this option to manually input seismic load values.
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| Shear Unit |
(Direct entry) Select the units of force used for shear values.
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| Moment Unit |
(Direct entry) Select the units of moment used for shear values.
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Convective Seismic Load / Impulsive Seismic Forces
The simplified model for seismic loads is that of a two component spring/mass. A short period, impulsive mode is assumed as the primary response mode. A secondary convective mode is assumed to account for the sloshing of fluid.
| Setting | Description |
|---|
| Operating Shear |
Type the lateral shear force due to the convective or impulsive force, respectively, under normal operating conditions.
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| Test Shear |
Type the lateral shear force due to the convective or impulsive force, respectively, under testing conditions.
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| Operating Moment |
Type the moment value due to the convective or impulsive force, respectively, under normal operating conditions.
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| Test Moment |
Type the moment value due to the convective or impulsive force, respectively, under testing conditions.
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Seismic Ground Motion Values - US Code
The program will calculate seismic loads per ASCE 7-2005 for you. You have the option to use database mapped acceleration values based on Zip code or to specify values directly.
- Select using Zip Code- Populates the Select Zip combo box with all U.S. zip codes. Choosing any one of them will (or simply type in the value to select faster) will selected mapped acceleration values for that geographic location.
- Enter Value Manually- Specify values for S1 and Ss in the respective fields.
| Setting | Description |
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City / Latitude / Longitude
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(non editable) Displayed for the specified zip code to verify location. |
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S1 / Ss
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The 1-second and short period acceleration values from ASCE 7 maps. |
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Site Class
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Value of Fa and Fv, which are functions of Site Class and mapped acceleration values.
Note: If Site Class is selected as F, Fa and Fv may be entered manually.
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Seismic Parameters
These values are specified when the Direct Seismic Load Input option is not set.
| Setting | Description |
|---|
| Seismic Use Group |
Select the use group as defined in ASCE 7.
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| Damping Adjustment Factor |
Type the damping adjustment factor. This may be varied to account for different fluids or soil conditions.
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| Long-Period Transition Period (TL) |
Type the value for TL.
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| Setting | Description |
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