INVESTIGATION OF CONCRETE BEAMS POST-TENSIONED WITH UNBONDED CFRP TENDONS

摘要

Concrete beams with a rectangular cross-section were post-tensioned using a single carbon fiber reinforced polymer (CFRP) tendon placed in a conduit. A commercially available tendon and a generic, non-commercial tendon were used. Steel pipes filled with an expansive cementitious grout provided anchorage for the unbonded beams. The post-tensioning procedure pre-loads external steel anchors against the ends of the beams while the grout inside each anchor cures and grips the tendon. Tension losses during various steps of the post-tensioning procedure are reported, as are details of the post-tensioning procedure. The beams were loaded in four-point flexure until failure while deflection, longitudinal strain in the tendon and movement of the free ends of the tendon relative to each anchor were monitored. All beams failed by compression of the concrete and in no case did a tendon slip through an anchor. Strains in the tendons at failure of the beams were well below ultimate values.