Areas can be used to create loads that are independent of the model. Area Loads are automatically distributed to model elements based on tributary areas and the Span Data. Area Loads are applied to selected areas using the Loading | Apply Area Loads command or the Ctrl+3 hotkey. Area Loads apply only to objects that lie within the boundary and plane of an area (i.e. loads will not project onto elements that are not in the plane).

Area Loads on Plates

When area loads are applied to plates, the pressures are transmitted directly to the plate elements within the plane and confines of the area. If there are holes in the plate mesh, then no load will be applied over this portion of the mesh (i.e. loads are not 'distributed' to nearby plates). If an area load extends beyond the plate element mesh or is completely within a single plate element (but not completely over that plate), then the loads may not be generated as expected. Enable the Generated Loads parameter under the Load Details in the Project Manager | Model Filter tab to validate how the loads were applied to the plates for analysis. A Generated Plate Loads report table can be created to validate how the load were applied to the plates.

Tributary Area Loads on Members

Area loads are distributed to members according to the Span Type specified for the area (either a one-way or two-way distribution can be chosen). Member Offsets will not prevent a member from receiving load from an area (i.e. members whose nodes lie in the plane of the area will be loaded). The Load Braces parameter for an Area can be disabled to prevent members with a bracing framing type from receiving any load from the area. Tributary area loads applied to members are generated numerically through numerical-integration, which is an approximation (the accuracy is a function of the size of the area, the arrangement of members in the plane, and the Project Manager | Modify | Performance settings in the project). Enable the Generated Loads parameter under the Load Details in the Project Manager | Model Filter tab to validate how the loads were applied to the members for analysis. A Generated Member Loads report table can be created to validate how the load were applied to the members.

ASCE 7 Wind Loads on Areas

VisualAnalysis has a built in wind-load generator that can help with ASCE 7 Wind load application. The generator is based on the Directional Procedure (Wind Loads on Building- MWFRS) in Chapter 27 of the ASCE 7 design specification for Enclosed and Partially Enclosed buildings (Open structures are not supported for Area Loads). The generator calculates the pressure on the area based on the wind parameters that are set for each load, each load case, and for the entire project.

Steps to Create Area Wind Loads:

1. Create one or more Areas to accept a wind load pressure
2. Select or Create a Service case with a Wind Load Source (Wind+X, Wind-X, Wind+X+Y, etc.)
3. Apply an Area Load(s) to the selected Area(s) using the Loading | Apply Area Load command in the wind load service case
4. Select the Area Load(s) and set their Type to ASCE 7 Wind in Area Loads section of the Project Manager | Modify tab. Also, specify the Apply To parameters.
5. Specify the Outward Area Normal parameter and select the Wind Surface from the dropdown in the Wind Load section of the Project Manager | Modify tab.
6. Define the Wind Parameters (Exposure Category, Enclosure Category, Project Width, etc.) for the specific Load Case by using the Loading | Edit Load Case command or in the Project Manager | Modify tab when a wind load is selected in the Model View.
7. Define the project wide IBC Wind parameters (Ground Elevation, Mean Roof Height, Wind Speed, Gust Factor) using the Loading | Edit Load Case command in any wind Load Case or in the Project Manager | Modify tab when a wind load is selected in the Model View.
8. The Calculated Pressure for a selected area load is displayed in the Wind Load section of the Project Manager | Modify tab. The calculated Area Wind Load pressures are also displayed in the Find Tool.

Area Side Loads

Requires: Advanced Level

A uniform force or moment can be applied to area sides (in any direction, including in the plane of the area) by selecting the side and using the Loading | Apply Area Side Load command.  The Area Side Load is distributed to the nodes along the edge (both manually created nodes and nodes from auto-meshing). If the sides for an area cannot be seen in the Model View, make sure the Sides parameter is enabled in the Area Details section of the Project Manager | Model Filter tab. If the sides are still not visible, select the area and enable the Auto Generate Sides? parameter in the Project Manager | Modify tab or use the Structure | Add Area Sides command to generate the sides manually.