Dear sir,

In case of pretension in ansys, the load stpe are divided into three stages, first load step should be prestrain only, then second with applying self weight and from third load steps onwards until failure, external loads are applied. It's clear for you I think so.

Then how can differentiate prestension and posttensioned Modeling in ansys.

I will tell my learning, in pretensioned concrete from first load step onwards the concrete steel interfaces are fully bonded until failure loads.

But in posttensioned case, whether it is bonded or unbonded, prior to the application of external loads(I. E. Up to prestress and self wt.) there won't be any bond between prestress steel and surrounding concret.

In unbonded case, the bond is always absent from initial loadstep to final loadstep. But in case of bonded one, upto self wt application, even though it is an bonded PT beams, but we need to keep unbond the prestress steel, becoz in post tensioned grouting is applied only after prestressing the wire, at this time the prestress force and self wt would be acted already, after that only we need to apply the bond condition, if it is unbonded post tensioned.

Now, for bonded case initially I use coupling nodes option to the extreme end nodes (two nodes only) of the P. S steel by fixed it in all three directions so that it can't move and will impart prestress to concrete, up to self wt application. When you are applying live loads you need to provide with combine39 spring element to provide the bond behaviour by applying coupling nodes in "Y, Z direction and assign the combine39 between coincident nodes only in the x - dire tion, so that the PS steel can move in x-direction.

For unbonded case only extreme end nodes of PS steel will we couple of merged in all x, y, z direction, and no any other actions are required through the simulation.

Hope it will help you. Thank you.

thank you so much Pandi Mani sir for your detailed answer.