Question
What is the reason for residual displacement occurring when loads are removed during the construction stage analysis?
I have a question regarding the construction stage analysis.
In Construction stage 1, I applied a load, and then I removed the load in Construction stage 2. While the moment and stress returned to zero, there was residual displacement left.
I am curious about how this mechanism works.
Answer
The strength development of concrete is considered in the analysis model.
Since the modulus of elasticity is determined by the strength of the concrete, it increases as the strength increases.
When a load is removed, the program internally considers applying a load in the opposite direction. In this case, because the age of the concrete when the load is applied and the age when the load is removed are different, the stiffness of the concrete becomes greater when the load is removed, causing residual deformation to remain even after the load is removed.
If the elastic modulus is the same when the load is considered and when it is removed, the residual displacement appears to be zero.