The User {Seismic, Wind} Loads on Diaphragms form can be used to specify a seismic load pattern or a wind load pattern by specifying the load in the X and Y directions around the moment Z.
Number of Load Sets edit box. Because the form offers a high degree of flexibility, any number of potential load sets could be specified. For example, both positive and negative load values can be specified on various levels and diaphragms at various locations. It is assumed that this edit box might be used to specify multiple load sets such that the positive values would be in one load set and the negative values in another.
On the User Wind Loads on Diaphragms form, the Loads are Reversible for Combos check box can be used to reverse the sign on the loads automatically when the load pattern is used in a load combination. Uncheck the check box to specify the sign of the loads in each load set yourself.
Tower drop-down list. If the Options menu > Allow Multiple Towers command is enabled, this drop-down list can be used to select the Tower to which the seismic or wind load pattern is being applied.
Story and Diaphragm drop-down lists. Use these drop-down lists to identify the location of the load relative to the overall structure.
Fx, Fy and Mz cells. Enter the values for the Seismic load or the Wind force at X and Y around Moment Z.
X Ordinate and Y Ordinate cells. Use these cells to specify the location of the seismic load or wind force.
On the User Seismic Loads on Diaphragms form, when the Apply Load at Diaphragm Center of Mass check box is checked, specification of these values is unnecessary so the columns are not displayed. In addition, when the Apply Load at Diaphragm Center of Mass check box is checked, the Additional Eccentricity Ratio (all Diaphragms) edit box becomes available. Use it to specify a value for eccentricity for all diaphragms. Five percent is the default and is entered as 0.05.
Right click in a cell of the spreadsheet to display commands to Copy and Paste data within the spreadsheet area. Standard Windows Copy and Paste commands can be used to copy and paste data into the spreadsheet from another program, such as Excel, assuming that the original data has the appropriate tabular format.
Use the Add Row and Delete Row(s) buttons to add or delete rows of data from the spreadsheet area.
Sort Rows button. Use this button to arrange the data according to Story level, in descending order.
See Also
Access the User { Seismic, Wind} Loads on Diaphragms form as follows:
Click the Define menu > Load Patterns command to access the Define Load Patterns form.
Type a unique name for the load pattern in the Load edit box, select Seismic (to define Seismic loads) or Wind (to define Wind loads) from the Type drop-down list, and select User Loads from the Auto Lateral Load drop-down list.
Click the Add New Load button
Highlight the newly define load case in the display area and click the Modify Lateral Load button.
After a Quake or Wind load pattern has been defined as described above, highlighting the name of the previously defined pattern and clicking the Modify Lateral Load button will also display the form.