The post tensioned tendon anchorages for a high rise building were installed without traditional hairpin reinforcing bracketing the dead ends of banded tendons under between 27 and 33 kips of tension.
The omitted reinforcing had the potential to impact life safety concerns on the part of the owner. GES Tech Group was retained to determine if the missing reinforcing resulted in a state of internal stress that was acceptable.
The investigation was formulated to compare the results of the as-built anchorage and the as-designed configuration. The non-linear FEA formulation was performed under the criteria of ACI 318 section 18.13.5. A refinement was included in the analysis that considered surface contact between the embedded steel anchor and the concrete surface.
Non-linear aspects that were thus included in the model formulation included potential cracked concrete and surface to surface contact discontinuities.
