- Enter pre-stress loads for beams, or modify or delete previously entered loads.
- The concept of defining the pre-stress loads in beams is illustrated below.
- The cable drape is located on a 2-D curve passing through 3 eccentric points. It is assumed that the eccentric points are on the beam element's local x-z plane. The tension in the cable is assumed to be uniform over the entire length of the drape.
- For accurate calculation results, after dividing the beam element into four segments, the program uses the following method to calculate equivalent loads on the beam element.
1. Calculate the equation corresponding to the cable drape.
2. Calculate the slope of the cable drape at each intersection at the end of four segments and the cable drape.
3. Shear, moment and distributed load for each segment can be calculated by the following equations:
(a) Beam member subject to a pre-stress load
(b) Equivalent load applied to the beam element by prestressing force
From the main menu, select [Load] tab > [Type : Prestress] > [Prestress Loads] group > [Prestress Beam Loads]
Prestress Beam Loads dialog box
Load Case Name
Assign the load case name. Click to the right to enter, additional load cases and modify or delete existing load cases.
Load Group Name
Select the desire Load Group that will include the entered Prestress Beam Loads data. Select "Default", if a Group assignment is unnecessary. Click to the right to add, modify or delete Load Groups.
Add : To enter new or additional pre-stress loads for beam elements
Replace : To replace previously entered pre-stress loads for beam elements
Delete : To delete previously entered pre-stress loads for beam elements
Refer to the figure under the Load Type selection field to enter the drape shape and pretension value.
Tension : Pretension Force (enter only a positive value)
Di : Cable drape in the local ± z -direction at the beam element start point (i-side N1 end)
Dm : Cable drape in local ± z -direction at the beam element mid-point
Dj : Cable drape in local ± z -direction at the beam element end point (j-side N2 end)
Define the method of selecting elements to which prestress loads will be applied.
Selection : Prestress load is applied to individual elements selected.
Line (by 2 Nodes) : Prestress load is applied to the elements selected by 2 nodes as a single element.