Adding prestressed loads to members in SkyCiv Structural 3D
Prestressing loads can be accessed at anytime in Structural 3D by visiting the top navigation bar, or, right clicking a member (or group of members) and clicking Add Member Prestress Load:
From here, the left menu will open up for you to enter or edit any prestressed forces in the model. The inputs required are member IDs, the prestressed load magnitude (+ for tension, – for compression) and the load group you wish to assign for this load.
Tip: you can enter comma separated members (e.g. 1,2,6) or a range (e.g. 3-6) or a combination of both (e.g.1,2,3-6) for easier and faster input!
Once submitted, the prestressed loads will appear in the GUI, with tension forces shown in blue and compression forces shown n red:
Adding Temperature Loads or Strain Loads using Member Prestress Loads
Users can add temperature loads or strain loads using member prestress loads to simulate the elongation and shrinkage of members due to temperature effects.
This axial strain (elongation and shrinkage) can be be applied using prestressing the member. If the member is shrinking that would be prestress tension. If the member is elongating then that would be a prestress compression. Thermal Expansion of Steel for instance is normally calculated by the following relationship:
ΔL = L0 α (t1 – t0)
where, ΔL = change in length
α = thermal expansion coefficient (m/moC, in/inoF)
t0 = initial temperature (oC, oF)
t1 = final temperature (oC, oF)
Once you have calculated the change in member length (for instance the elongation), the prestress force is calculated by the following relationship: