Member Loading

In Member Loading individual members are selected and loads applied to them to act directly on the chosen members. Other methods of applying loads within MasterFrame include Area Loading and Wind Loading which apply gravity loads over a floor area or wind loads over a building envelope. These loads are then automatically distributed by the program on to the frame members. See the manual sections on Area Loading and Wind Loading below for details on how to apply these loads to a frame.

To apply member loads, select Member Loading from the Loads menu at the top of the screen.  If you are currently in either the Member Section Properties or Member Angle area you can shortcut to the Member Loading by clicking on the  button at the top right of the screen.

In the bottom left of the screen a set of Add Loads icons will appear. To expand these click on the ‘More Loads’ button.

The Member Loading area can be used in three different modes, i.e. Member , Global  and Copy To   modes, in very similar fashion to the section properties and member orientation areas.

Member Mode

Member Mode is the default mode and perhaps the mode that you will use most frequently.

In Member mode you can apply and edit loads on a member-by-member basis.  To do this,

1.Select the member you want to apply or change the loads on.  You can select a member by,

a)clicking on it in the main frame geometry area, or

b)if you know the member number you wish to edit then you enter the number in the 

c)by selecting the member number from the

The selected member is highlighted in 3D member profile in the frame geometry window.  For this reason it is recommended not to turn on the global 3D member profile option from the top tool bar while working in this area.

Using the Member Loading application buttons apply the desired load types on the member.  The loads will appear in the list of loads in the loads editing area.

Use the Loads Editing Area to define the magnitude, direction and load group of each load.  See Using the Loads Editing Area below.

While in member mode all changes made in the loads editing area are automatically applied to the selected member.  All changes made affect the current selected member only.

When you select a member in member mode, the current member loads on that member are listed in the loads editing area.  Therefore member mode can be used to investigate the current loads on members.

Global Mode

Global mode is used to change the member loads on a group of members that have the same pattern of loads or single load applied. In other words global mode can be used to change all occurrences of the same single load/load pattern at once.

Global mode groups member together that have the same single load or load pattern depending on which option is selected. Beneath the global mode icon the drop list indicates how many different member groups have been created, i.e. how many different single load/load patterns are currently applied in the frame.

The difference between the single load and load pattern options is best understood by the following simple example. The four members shown have member loads applied to them.

While in Global (Load Pattern) mode the program will create a group of the members that have the same configuration of loads applied. Hence here three groups will be generated comprising of,

Member Load Group 001 – M1

Member Load Group 002 – M2 and M3

Member Load Group 003 – M4

No Loads – in this example there are no members in the group since all members are loaded.

When in Global (Single Load) mode the members that have the same single item of load applied will be grouped together. Since in this example only two different items of load exist only two groups have been created.

D1 UDLY –005.00 (kN/m) – M1, M2 & M3

L1 UDLY –007.00 (kN/m) – M2, M3 & M4

To change member loads while in global mode,

1.Click on the  icon to switch to Global mode. 

2.Select to work in either single load or load pattern, depending on how you wish to change your loads.

3.Select the existing Single Load/ Load Pattern you wish to change from the drop list.

Tip: When in Load Pattern mode a group may be selected by clicking on a member in the frame geometry area.

The members in the group are highlighted in red on the screen, i.e. the highlighted members all have the same single load or pattern of loads.

1.Edit the member loads in the loads editing area. Items of load can also be either added or deleted.  See Using the Loads Editing Area below.

As in member mode the changes are applied automatically to all members in the currently selected group. Once you are finished in Global mode it is recommended that you return to the Member mode.

Copy To Mode

This is one of the most powerful editing modes, which is used for copying an arrangement of member load(s) to a member or group of members in one operation.

The key concept in Copy To mode is that the List of Loads in the Loads Editing Area becomes the template of information to be pasted onto the members you select.  In this sense the Copy To mode differs greatly from the Member and Global modes in that if you change information in the List of Loads, you are not changing any existing loads on the frame.  Copy To can be used can be used in either Add/Delete or Replace Loads mode. 

In Copy To (Add/Delete) mode the loads in the template (list of loads) are applied to selected members in addition to any existing loads.  If the loads that are being copied already exist on a selected member then the loads are deleted from that member.

In Copy To (Replace Loads) mode the loads that are being copied will replace any existing loads on the selected members.

To use the Copy To mode,

1.Click on the  icon to switch to Copy To mode. 

2.Select to work in either Add/Delete or Replace Loads.

3.Set up the loads to be copied in the template.  This can be done either by,

a)Selecting an existing pattern of loads (Member Load Template) or existing single load from the drop list.

b)Using the Loads Editing Area.

As you edit the loads in the template, members that match the modified template are shown in red.  All other members are shown in black

1.Paste this information onto the frame by selecting member(s) in the frame geometry area.  You can select member(s) by,

a)Clicking on individual members. 

b)Windowing a group of members

In Copy To (Add/Delete) mode, when you select members the loads in the template are applied to the members in black and removed from members in red.  Hence the Copy To can be used to add and remove member loads.

Copy To mode can continue to be used by repeating steps 3 and 4.

Important Note: Bear in mind that when you are in Copy To mode that when you select a member you have changed the loads on that member.  It is vitally important to be aware which editing mode you are in, since haphazardly selecting members while in Copy To mode could disrupt your model.  Remember that in Member and Global modes, changes are made as you edit. In Copy mode changes are only made when you click or select members in the frame geometry area.

Tip! When you are finished using Copy To, move back to Member mode.  Member mode is safer in that when you select a member you are not changing anything by doing so.

Using The Loads Editing Area

The list of loads in the editing area represents the loads on the selected member when in Member mode, the loads on a group of members when in Global mode, and the loads to be copied to members when in Copy To mode.

To add loads to the list click on one of the loads type application buttons.  Each of these loads types is described in further detail below. 

The loads added will appear on the list on the right of the screen.  The load definition in the list will contain information about its Load Group, load type, direction, magnitude, and dimensions (where applicable). 

A typical example of a member point load PY is shown below.

D1 PY  -050.000   1.520     (kN, m)   where,

D1                    Load Group – Dead Load in Load Set 1

P                    Load Type. Non-editable

Y                    Load Direction

-050.00          Load Sign and magnitude

1.520                    Distance of the point loads from end1 (lower node number) of the member

(kN, m)          Indicates the units for the numerical values in the load type.  In this case we can

see that the first value is a load in kNs, while the second value is distance in metres.

Non-editable.

The items in the list of loads can be directly edited from the keyboard. Any editable item can be changed by clicking on the relevant text to position the red cursor. Text can be directly entered from the keyboard starting from the location of the red cursor. The position of the red cursor can be changed using the mouse or using the arrow keys on the keyboard. Note that it is not possible to enter an invalid character for load group and load direction.

To edit a load that has been added to the list:

1.Firstly, select the load in the list by clicking on any character in the load definition

2.The load group can be changed by either,

a)selecting the load group and load set from the drop lists at the bottom right of the screen

b)Over-typing the load group text, e.g. D1, in the load definition.  Click on D to place the red cursor and then type one of the load group letters, i.e. D, L, W or N.  The red cursor will move to the number, where a number between 0 and 9 can be typed.  The items in the drop list below should change to reflect what has been entered.

3.The load direction can be changed by either,

a)Clicking on one of the load direction buttons

b)Typing the load direction directly in the load definition by entering X, Y, W, Z, N or M from the keyboard.  The load direction types are described in more detail below.

4.Change the numerical values of load magnitude or load distances directly in the load definition from the key board.  Note that the position of the decimal point in a value can be changed.  The  buttons can also be used to change the sign of the forces in the load definition.

To delete a load

1.Select the load in the list by clicking on any character in the load definition

2.Press the  at the bottom right of the screen

Other options in the loads editing area include:-

For some items in the load list, the order that they appear in the list can influence their effect. The sort spin button will move the selected load’s position in the list.

By clicking on the horizontal spin button to the right of the text box the currently selected load will move on the member by the increment in metres specified in the text box. Only member loads with distance definitions are influenced by this function.

The second spin button will change the load group of all the loads in the list in the order of D, L, W and N. For example, if we have two loads in the list with load groups D1 and L2, then these would be changed to L1 and W2.

The third spin button will increase or decrease the load set number of all the loads in the list. Again taking the example, as above, the load sets could be changes to D2 and L3.

Graphical Display of Loads in the Editor

The loads in the list are graphically displayed in the Selected Member graphics window at the top right of the screen. 

The graphical display is controlled by the options at the right of the screen.

Draw Current Member will display a load diagram of the total loads on the member, while the Draw Current Load option will only display the load that is currently selected in the list.

Spin button to graphically move the origin of the load(s) relative to the centre line of the member

Increase (up button) /decrease (down button) the graphical scale of the distributed member loads

Increase (up button) /decrease (down button) the graphical scale of the point member loads

Display numerical value of current member load or total member loads depending on which Draw Current option is selected.  The value displayed is always in kN/m units for the distributed load and kN for point loads.

If the loads are not visible it may be their graphical scale needs to be increased.

Tip:  The thick blue line on one side of the distributed member load diagram can be thought of as the arrowhead of the load direction, while the side where the value is displayed is the tail of the arrow.  This will help to clarify the load direction.

The frame load diagram can also be displayed which draws all the loads for the current frame view in the frame geometry area.  Press the button in the top tool bar.

  See section on the Top Toolbar for further description of this utility.

Load Directions

Each member load type can have a number of different load directions.  In a load definition the load direction is indicated by the character at the end of the load type.  For example, in the load definition,

D1 UDLY  -050.000          (kN/m) 

UDL is the load type and Y is the load direction.  The various different load directions are described below.

Y Load Direction

Global Y axis, where a negative value of load acts downwards.  In the case of distributed loads the load is applied over the horizontal projected length of the member.

X Load Direction

Global X axis, where a positive value of load acts from left to right.  In the case of distributed loads the load is applied over the length of the member projected onto the YZ plane.

Z Load Direction

Global Z axis, where a positive value of load acts from front to back.  In the case of distributed loads the load is applied over the length of the member projected onto the XY plane.

W Load Direction

Y direction distributed load calculated for true member length and not just the X-Z plane projection.  Useful for applied self-weight UDL in kN/m units. This load direction is only applicable to the UDL load type

N Load Direction

Load direction normal to the major axis of the member. 

The positive direction of the load depends on the node numbering of the member, and is found by rotating 90 deg anti-clockwise from direction of member from lower to higher node. 

M Load Direction

Load direction normal to the minor axis of the member.

Tip: When unsure about the load direction or sign convention it is best to rely on graphical validation since this will always be correct.

Member Load Types

When one of the member load type buttons are pressed, the associated load type is added to the list in the loads editing area.  The use of the loads editing area is described above.  The purpose and format of each of the load types is described here.

Standard Member Loads

In the following descriptions the load direction indicator in the load definition is underlined, e.g. in UDLY the Y character defines the load direction. See above for load directions available.

UDLY

Applies a uniformly distributed load W (kN/m) over the full (projected horizontal) length of the member. 

D1 UDLY          -000.000             ( kN/m )                     

                    W (kN/m)

PY

Applies a point load F in the specified load direction at a distance x measured along the member axis from the lower node number.

D1 PY     –000.000     0.000       ( kN,m )

                    F(kN)              x(m)

PTRY

Applies a partially distributed triangular load starting at a distance x1 with the intensity W1 going to the distance x2 with the intensity W2.  All distances are measured from the lower node number.

D1 PTRY    –000.000   0.000   0.000   –000.000

               W1(kN/m)   x1(m)   x2(m)   W2(kN/m)

PDLY

Applies a partially distributed load W based on the total  load F between the x1 and x2 dimensions measured along the length of the member from the lower node number.

D1 PDLY    –000.000   0.000   0.000   (kN,m,m)

                    F (kN)   x1(m)  x2(m)

TY1,2

The total load F is distributed over the full member length in a triangular pattern.  The distributed load varies from the maximum intensity W(kN/m) at one end of the member to zero intensity at the other end.  For TY1 the W occurs at end 1 of the member, and for TY2 W occurs at end 2 of the member.  W = F * 2 /L.

D1 TY1    -000.000        ( kN )

                    F (kN)

TYC

The total load F is distributed over the full member length in a triangular pattern.  The distributed load varies from zero at one end to the maximum intensity W(kN/m) at the centre of the member, then back to zero at the other end .  W = F * 2 /L.

D1 TYC     -000.000       ( kN )

                    F (kN)

TRY

The total load F is distributed over the full member length in a trapezoidal pattern.  The distributed load varies from zero at end 1 to the maximum intensity W(kN/m) at the x1 distance, remaining at that intensity to the x2 distance, then returning to zero at end 2 of the member.

D1 TRY   -000.000    0.000    0.000    (kN,m,m)

                    F (kN)            x1(m)             x2(m)

PTY1

The total load F is distributed over a partial length of the member in a triangular pattern.  The distributed load varies from the maximum intensity W(kN/m) at a distance of x1(m) along the member to zero intensity at the x2(m) distance end.  All distances are measured from the lower node number.  W = F * 2 /(x2 - x1).

D1 PTY1   -000.000    0.000    0.000   (kN,m,m)

                    F (kN)    x1(m)    x2(m)

PTY2

As per PTY1, however with the zero intensity located at x1 and the maximum intensity W (KN/m) located at the x2.  W = F * 2 /(x2 - x1).

D1 PTY1 -000.000 0.000 0.000 (kN,m,m)

              F (kN)   x1(m)   x2(m)

PMN

Applies a point moment M in the specified load direction at the distance x1 measured long the member axis from the lower node number.

D1 PMN   +000.000    0.000    (kN.m,m)

                 M (kN.m)  x1(m)

EM1,2

Applies the moments M1 and M2 to the local major axis of the member at end 1 and end 2 respectively.  Note that no other load directions apply in the load type.

D1 EM1   +000.000    EM2    +000.000    (kN.m)

               M1(kN.m)                     M2(kN.m)

EndM

Applies moments Mz to the major axis and My to the minor axis at the specified end node n (1 or 2) of the member.

D1 EndM 1    +000.000    +000.000    (Mz, My)

             n      Mz(kN.m)     My(kN.m)

Density

Applies a local density to a member.  This option should not to be used in conjunction with the global density option found from the Properties or Loads menus, which automatically applies a single density to all members in the structure. 

D1 D     024.000     ( kN/m3 )

          D (kN/m3)

Rise

Defines the temperature differential on a member for the application of thermal loading.  Note that it is essential that the member has a defined co-efficient of thermal expansion either from the global definition in the Properties menu or locally from the Loads menu – see below.

D1 DT    +000.000          (Degree C)

Co-

Applies a Co-efficient of thermal expansion to the member.  This is more of a material property of the member rather than a load.  Thermal loading is not applied to the member until a temperature differential value is applied through the Rise load type. See above.  Like the density a global value of thermal expansion co-efficient can be applied to all member from the Properties menu, in which instance this local member definition should not be used.  The value of the co-efficient represents the amount of thermal strain that is produced through a 1 degree Celsius rise in temperature.

D1 Alpha  12.0E-6 (Thermal Expansion)

Short

Applies a shortening of a member along its length. This will result in the strain due to the shortening of the member being taken up in the rest of the frame. Note that the shortening is defined in metres.

D1 DL  -00.000 (m)

Torq ecc

The torq ecc. has the effect of offsetting the member loads from the shear centre of the member in both the members local major (ey) and minor axis (ex), hence creating a torque load on the member.  The torque eccentricities specified apply to all member loads that follow after it in the list of loads applied to that member.  Hence the following example shows how a UDL on a member is made eccentric by 50mm from the minor axis to create a torque force, while the point load remains applied relative to the shear centre of the member.

D1 PY      050.000     01.550    ( kN, m)

UT Torq  ex +0.050 ey +0.000 ( m, m )

D1 UDLY       015.000             ( kN/m )

For further information on applying torsional loads and loading on asymmetrical members and their shear centres follow this technical note link.

Frame Spacing

The frame spacing has the effect of multiplying all loads that follow after it in the list of loads by the specified factor.  The frame spacing value is entered in meter units.  For example, when using a frame spacing along with a UDL, the value entered for the UDL can be thought of as the area (kN/m²) load since it will be multiplied by the spacing value.

UT Spacing 01.000 (Multiply AllLoads)

Note: MasterFrame will move the position of the Spacing definition to the top of the list of loads during analysis, therefore ensuring that the multiplication factor is applied to all loads on that member.