Precast prestressed beam - prestressing loss due to elastic shortening of concrete

When I provide the prestressing force there is a problem in Sofistik with calculation the prestressing loss due to elastic shortening of concrete - Sofistik doesn’t do that. Is there any solution for it (the best with considering the Young Modulus change in time) or I must calculate it per hand?

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Hello Paula,
the losses from elastic shortening are considered!
However, whether these losses occur or not depends on the point in time at which the tendon is grouted. Attached you find an adapted example with straight tendons without tensioning force losses.
If it is calculated with input line 361, grouting only takes place after prestressing. Then, of course, the full prestressing force is applied, see 01a and 01b.jpg.
If calculated with input line 362, the tendons are already grouted during shortening and then we obtain lower stresses, see 01c and 01d.jpg.

I hope that helps.
Best regards,
Jost
csm31_design.dat (43.2 KB)




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