Hello Dr. Pryl,

This is in reference to ATENA version 5.6.1.

I'm currently modeling a beam that ultimately failed in flexure due to an insufficient lap splice between rebar and prestressing strands. In order to simulate this failure mode, I've attempted to implement the Bigaj bond model to the prestressing strands. Since the bond model takes bar diameter as an input, I've used the equivalent diameter that would give me the area of the strand (in this case, 0.495 inches diameter to give me an area of 0.192 in2.). I've also used the circumsphere that is automatically calculated from this bar diameter when determining the bar properties.

However, this leads to an underestimation in the transfer length of the strand (determined by checking the cable force along the strand after applying a prestressing force). Since the transfer length became so short, it was not possible to simulate the observed failure mode that we were trying to model; as such, I then manually decreased the circumsphere until the transfer length matched the value determined from building codes and standards.

Although this generated the correct failure mode, the failures were often premature in some beams likely due to the much smaller than expected circumsphere. I was wondering if there was an accepted practice when it comes to dealing with prestressing strand bond regarding the determination of the different parameters like bar diameter and circumsphere, as there wasn't much I could find regarding this in the literature.

Thank you as always!

mqambar