Predicting bond formulations for prestressed concrete elements

• An experimental database of transmission length values for prestressed concrete elements is gathered.
• Substantial weakness in terms of predicting capacity of existing models is found.
• New general formulations for transmission length is proposed.
• Refined statistical analyses are performed for the validation of the new proposal.

One of the most important features in design of pretensioned concrete elements is the determination of correct transmission (transfer) length. A number of formulations have been proposed by some authors, codes and guidelines but, although a huge experimental literature is available, the problem does not seem completely solved. In this work an experimental database of measured values of transmission length in prestressed concrete specimens is gathered and an assessment of some current formulations is developed. A statistical analysis is also performed in order to identify the effect of the main variables influencing transmission length. Some useful information is obtained and can be eventually used for a possible validation/improvement of actual relations; a new formulation for transmission length evaluation is also proposed.