Testing of Large Curved Prestressing Tendons

Previous testing had demonstrated that sufficient paths for grout flow were maintained in post-tensioned strand tendons regardless of the curvature and the resulting radial forces which packed the strands together. This conclusion was further confirmed by grouting two post-tensioned tendons of about 2,000 kips ultimate strength. The two tendons represented hoop tendons draped over an under the equipment hatch of the reactor containment building, which is a circular opening in a concrete cylinder. Because of the nature of the grouting test, an opportunity existed for making tests to confirm values of friction and bond. While the friction tests were limited, they indicated that a curvature friction coefficient, ?, of 0.30 is appropriate for large tendons which are unlubricated. The bond test indicated that bonding by grout of the strand tendon to the duct is effective for tendons of large capacity.