Prestressed concrete bars which consist of high performance concrete having a compression strength f_(ck) >= 85 N/mm~2 can be used as reinforcing elements for tensile forces in concrete members. Prestressing is accomplished by a centrically positioned highly prestressed strand St 1570/1770 by pretension. Prestressed concrete bars can only maintain their positive properties, if the prestressing force is permanently kept on high level. In this paper an algorithm is presented which allows a computation for state I of the loss of prestressing force due to shrinkage and creeping after casting the concrete member.
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机译：由抗压强度f_（ck）> = 85 N / mm〜2的高性能混凝土组成的预应力混凝土钢筋可用作混凝土构件中拉力的增强元件。预应力是通过居中放置的高预应力钢绞线St 1570/1770通过预拉伸来完成的。如果预应力永久保持在较高水平，则预应力混凝土钢筋只能保持其积极性能。本文提出了一种算法，该算法可以计算由于浇铸混凝土构件后的收缩和蠕变引起的预应力损失的状态I。
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