Patch Loads (2019+)

The program also enables the application of general gravity patch loads to an area of panels in which gravity area loading has been applied. It can be seen as providing additional loading over a specific area on top of the area loads already on the panels.

A patch load can be applied to a panel or over a range of panels and its location is simply measured relative to a particular member, which acts as a datum or can be manually drawn on the floor levels of the model. The patch load will be distributed according to the span characteristics of the panel, i.e. one way or two way spanning.

Each definition of patch load is given an individual name and stored in the patch load group. The information held in the group relates to the position and dimensions of the patch load relative to a member and also the magnitude of dead and live loading in kN/m.

Patch loads can be placed over area loading panels. The patch load will be resolved according to the direction of span of the panel and transferred to the panel’s supporting members.

Notes

•If your patch load, or part of it, lies beyond the external bounds of the area loading panels, the portion of load beyond the boundary members will not be taken into account.

Opening the Patch Load Editor

1.Open the Area Loading Editor

By default, the Area Loading Editor should open on the “Area Loading Panel Groups” tab. The Line Loads button is the fourth button to the right of it.

2.Click the Patch Loads button

Alternatively, go to the Loads > Floor and Roof Panels – Area Loading and Construction (Pro) > Patch Loads on Panels  option on the top menu.

Adding a Patch Load

   Add an item, ie, a new patch load.

   Copy the selected item and add a new item to be the same as the copied item.

   Delete items.

   Select All items. Use standard windows Shift and Ctrl to multi-select items.

   Inverts the current selection of items.

1.Click on the Add an Item button .

The remainder of the procedure to add patch loads essentially follows that of placing line loads on the floors, except for the following minor differences.

The Placement Method only includes 2 options now – Offset from a Member or the Draw method. The Offset from a Member option is the same as that for the line loads above. The Draw method is slightly different in that instead of drawing a line between 2 points, the Place Mode allows for the drawing of Polygonal shapes, Rectangles or Picking Panels which have previously been created.

For Polygonal shapes you can pick a series of points to define the polygon, ensuring that the polygon is a closed region.

Note that the load boundary can be moved graphically. Click on the particular load to highlight its perimeter in red. Handles will appear at the ends and centre of the perimeter lines around the load. Any one of these can be dragged to a new position to move the load.

For the Rectangle placement method select 2 diagonally opposite corners and the enclosed rectangle will fill in.

For the Pick Panels placement method just click on a panel to infill it.

Varying Patch Loads Method

A patch load with varying values can be set up easily. Set the Varying Load option to Yes and then enter three ratios for 3 points on the perimeter of the varying patch load. Finally select the 3 points that these ratios apply to by first clicking on the grey box at the right hand end of the Varying Points cell, then click on the 3 individual points.

This feature would be useful when applying snow loading to the valley of a portal roof, for example.

The Edit Tools options are the same as for the line load so the patch load can be moved laterally, rotated, copied or removed. An additional tool is the Clean Up option  which will delete lines that do not form patch shapes and so keep the input tidy.