Multiframe allows loading on members to be applied relative to the direction of the global coordinate system or relative to the direction of the local member coordinate system.  Loads that are applied at an angle to either of these systems, can be modelled by using vector components of the loads.

A global distributed load is a load which is distributed along all or part of a member, and acts in a direction parallel to one of the reference x, y or z axes.

To apply a global distributed load to a member

§    Select the member or members to be loaded

§    Choose Global Dist'd Load from the Load menu or short cut menu

A dialog box will appear with icons to indicate the shape and direction of loading.

§    Click on the icon which shows the shape of the load

In a two dimensional view, there will be four icons indicating the four possible loading directions.  In the 3D view, all six possible icons will be displayed with the patterns in the icons showing the direction of the action of the loads.  Each icon has a pattern with lines running parallel to the direction of action.

§    Click on the icon which shows the direction in which the load is to act

§    Type in values for the magnitude of the load at each end

§    Click the axes in which to apply the load

The axis of the load determines how the load is distributed along the members. With Global or Projected axes, the magnitude of a global distributed load refers to its load per length where the length is measured perpendicular to the direction of the load.  This means a vertical distributed load applied to an inclined member will apply a total load equivalent to the magnitude of the load times the horizontal projected length of the member.  For loads applied in local axes, the magnitude of the distributed load refers to its load per length where the length is the actual length of the load measured along the member.

§    Click on the OK button

Note that when working in dialog boxes, you can use the Tab key to move from one editing box to the next.  If you do this in this case, the right hand end magnitude will automatically be set to the same value as the left hand end magnitude.  You may type over this second value if you wish to have a non-uniform load.

There is no need to enter '+' or '-' signs for your load magnitudes.  The directions are determined from the icon that you select.

When you enter positions of loads in the member loading dialogs or the Data window, you can enter calculation expressions for the position.  For example, if you want a load to start at one third span you can enter L/3 for its start position.  If you enter this in a load dialog, this expression will be calculated for all the selected members.  This means you can apply this load to a number of members of different lengths simultaneously.  You can also enter more complicated expressions such as 2*L/3 or 1.35+(L-4)/2.  The variable L is always available and contains the length of the member, the syntax of the expressions is the same as that used in the CalcSheet.