Experiments on Continuous Unbonded Post-Tensioned Beams with 2400 MPa (350 ksi) Strands

Experiments on seven two-span unbonded post-tensioned beams were conducted under four-point static loading conditions. Variables considered included: strand type (nominal tensile strength); tendon drape (height of tendon profile); and magnitude of prestress. Experimental emphasis was placed on the applicability of using higher-strength 2400 MPa (350 ksi) strands instead of ordinary 1860 MPa (270 ksi) strands in unbonded post-tensioned beam members. Observed results revealed that specimens with 2400 MPa (350 ksi) tensile strength 15.2 mm (0.6 in.) diameter strands developed equivalent tendon stress increment, load-carrying capacity, and flexural ductility while at the ultimate limit state having earlier and wider plastic hinge.