Answer:
By selecting the load type "End Prestress" in the load definition of RFEM 5, the program increases the load internally until the axial force equals the prestress force.
You can display the internal load by displaying the continuous deformation load in the x-direction in the Results navigator.
This results in a deformation of −0.00168 for the end prestress of the structural system. With the modulus of elasticity of the member and the cross-section of it, you can also determine the initial prestress:
V = ɛ * E * A = 0.00168 * 21,000 * 7.07 = 249.4 kN
