In 2020, a multi-story condo building in Virginia was experiencing severe cracking in balcony slabs at multiple levels. GES Tech Group was retained to evaluate the evidence of distress, determine the cause (design or construction issue), assess the risk to the structure and residents, and recommend repair procedures.
The cause of the balcony cracking was determined to be termination of several post tensioned tendons in the slab rather than in the perimeter shear wall, as was intended by the designers. Accumulated strain due to the defective anchorage resulted in a unique crack pattern in the balcony slabs.
Delamination at the balcony edges was determined to have been caused by embedded re-bar under shear stress due to the slab anchorage of the tendons. Extensive linear and non-linear FEA modeling of the complex structural mechanics in the area of interest determined that the balconies were stable following the inadvertent stress relief provided by the various cracks. Epoxy injection of cracks, and relieving the shear stress on the embedded re-bar, addressed the issue. No additional repairs were recommended.
